diff --git a/DESCRIPTION b/DESCRIPTION
index 60262826..1bd3af1c 100644
--- a/DESCRIPTION
+++ b/DESCRIPTION
@@ -15,6 +15,7 @@ LazyData: true
 Encoding: UTF-8
 Depends: R(>= 3.5.0)
 Imports:
+    assertthat,
     caret,
     cli,
     dplyr,
diff --git a/R/fftrees_apply.R b/R/fftrees_apply.R
index 572a7e88..2aa76989 100644
--- a/R/fftrees_apply.R
+++ b/R/fftrees_apply.R
@@ -636,6 +636,30 @@ fftrees_apply <- function(x,
 
     # Add final tree results to level_stats_ls and decisions_ls: ----
 
+
+    # Add marginal classification statistics to level_stats / Frequencies per level:
+
+    level_stats_i$hi_m <- NA # initialize marginal freqs
+    level_stats_i$fa_m <- NA
+    level_stats_i$mi_m <- NA
+    level_stats_i$cr_m <- NA
+
+    for (i in 1:level_n) {
+      if (i == 1) {
+        level_stats_i$hi_m[1] <- level_stats_i$hi[1]
+        level_stats_i$fa_m[1] <- level_stats_i$fa[1]
+        level_stats_i$mi_m[1] <- level_stats_i$mi[1]
+        level_stats_i$cr_m[1] <- level_stats_i$cr[1]
+      }
+
+      if (i > 1) {
+        level_stats_i$hi_m[i] <- level_stats_i$hi[i] - level_stats_i$hi[i - 1]
+        level_stats_i$fa_m[i] <- level_stats_i$fa[i] - level_stats_i$fa[i - 1]
+        level_stats_i$mi_m[i] <- level_stats_i$mi[i] - level_stats_i$mi[i - 1]
+        level_stats_i$cr_m[i] <- level_stats_i$cr[i] - level_stats_i$cr[i - 1]
+      }
+    } # for n_levels.
+
     level_stats_ls[[tree_i]] <- level_stats_i
 
     decisions_ls[[tree_i]] <- decisions_df[ , names(decisions_df) %in% c("current_decision", "current_cue_values") == FALSE]
@@ -670,7 +694,6 @@ fftrees_apply <- function(x,
 
   }
 
-
   # Add results to x$trees (given mydata type): ----
 
   x$trees$stats[[mydata]]       <- tibble::as_tibble(tree_stats)
diff --git a/R/plotFFTrees_function.R b/R/plotFFTrees_function.R
index 8fe72957..42a3e90f 100644
--- a/R/plotFFTrees_function.R
+++ b/R/plotFFTrees_function.R
@@ -34,7 +34,7 @@
 #'   \item{'cues'}{Plot only the marginal accuracy of cues in ROC space.
 #'   Note that cue accuracies are \emph{not} shown when calling \code{what = 'all'} and use the \code{\link{showcues}} function.}
 #'   \item{'icontree'}{Plot tree diagram with icon arrays on exit nodes.
-#'   Consider also setting \code{n.per.icon} and \code{show.iconguide}.}
+#'   Consider also setting \code{n_per_icon} and \code{show.iconguide}.}
 #'   \item{'tree'}{Plot only the tree diagram.}
 #'   \item{'roc'}{Plot only the performance of tree(s) (and comparison algorithms) in ROC space.}
 #' }
@@ -74,7 +74,7 @@
 #' @param label.tree A label for the FFT (optional, as character string).
 #' @param label.performance A label for the performance section (optional, as character string).
 #'
-#' @param n.per.icon The number of cases represented by each icon (as numeric).
+#' @param n_per_icon The number of cases represented by each icon (as numeric).
 #' @param level.type The type of performance levels to be drawn at the bottom (as character string, either \code{"bar"} or \code{"line"}.
 #' Default: \code{level.type = "bar"}.
 #'
@@ -98,36 +98,43 @@
 #'
 #' @examples
 #' # Create FFTs (for heartdisease data):
-#' heart_fft <- FFTrees(formula = diagnosis ~ .,
-#'                      data = heart.train)
+#' heart_fft <- FFTrees(
+#'   formula = diagnosis ~ .,
+#'   data = heart.train
+#' )
 #'
 #' # Visualize the default FFT (Tree #1, what = 'all'):
-#' plot(heart_fft, main = "Heart disease",
-#'      decision.labels = c("Absent", "Present"))
+#' plot(heart_fft,
+#'   main = "Heart disease",
+#'   decision.labels = c("Absent", "Present")
+#' )
 #'
 #' # Visualize cue accuracies (in ROC space):
-#' plot(heart_fft, what = "cues",  main = "Cue accuracies for heart disease data")
+#' plot(heart_fft, what = "cues", main = "Cue accuracies for heart disease data")
 #'
 #' # Visualize tree diagram with icon arrays on exit nodes:
-#' plot(heart_fft, what = "icontree", n.per.icon = 2,
-#'      main = "Diagnosing heart disease")
+#' plot(heart_fft,
+#'   what = "icontree", n_per_icon = 2,
+#'   main = "Diagnosing heart disease"
+#' )
 #'
 #' # Visualize performance comparison in ROC space:
 #' plot(heart_fft, what = "roc", main = "Performance comparison for heart disease data")
 #'
 #' # Visualize predictions of FFT #2 (for new test data) with custom options:
-#' plot(heart_fft, tree = 2, data = heart.test,
-#'      main = "Predicting heart disease",
-#'      cue.labels = c("1. thal?", "2. cp?", "3. ca?", "4. exang"),
-#'      decision.labels = c("ok", "treat"), truth.labels = c("Healthy", "Sick"),
-#'      n.per.icon = 2,
-#'      show.header = TRUE, show.confusion = TRUE, show.levels = TRUE, show.roc = TRUE,
-#'      hlines = FALSE, font = 3, col = "steelblue")
+#' plot(heart_fft,
+#'   tree = 2, data = heart.test,
+#'   main = "Predicting heart disease",
+#'   cue.labels = c("1. thal?", "2. cp?", "3. ca?", "4. exang"),
+#'   decision.labels = c("ok", "treat"), truth.labels = c("Healthy", "Sick"),
+#'   n_per_icon = 2,
+#'   show.header = TRUE, show.confusion = TRUE, show.levels = TRUE, show.roc = TRUE,
+#'   hlines = FALSE, font = 3, col = "steelblue"
+#' )
 #'
 #' # # For details, see
 #' # vignette("FFTrees_plot", package = "FFTrees")
 #'
-#'
 #' @family plot functions
 #'
 #' @seealso
@@ -145,7 +152,7 @@
 plot.FFTrees <- function(x = NULL,
                          #
                          data = "train",
-                         what = "all",  # valid_what <- c("all", "default",  "cues",  "tree", "icontree",  "roc")
+                         what = "all", # valid_what <- c("all", "default",  "cues",  "tree", "icontree",  "roc")
                          tree = 1,
                          #
                          main = NULL,
@@ -153,7 +160,7 @@ plot.FFTrees <- function(x = NULL,
                          decision.labels = NULL,
                          truth.labels = NULL,
                          #
-                         cue.cex = NULL,
+                         cue.cex = 1.5,
                          threshold.cex = NULL,
                          decision.cex = 1,
                          #
@@ -170,78 +177,66 @@ plot.FFTrees <- function(x = NULL,
                          hlines = TRUE,
                          label.tree = NULL,
                          label.performance = NULL,
-                         n.per.icon = NULL,
+                         n_per_icon = NULL,
                          level.type = "bar",
                          # deprecated arguments:
-                         which.tree = NULL,      # deprecated: Use tree instead.
-                         decision.names = NULL,  # deprecated: Use decision.labels instead.
-                         stats = NULL,           # deprecated: Use what = "all" or what = "tree" instead.
+                         which.tree = NULL, # deprecated: Use tree instead.
+                         decision.names = NULL, # deprecated: Use decision.labels instead.
+                         stats = NULL, # deprecated: Use what = "all" or what = "tree" instead.
                          grayscale = FALSE,
                          # graphical parameters:
                          ...) {
-
-  # Prepare: ------
+  # Setup ------------------------------------------------------------------------
 
   par0 <- par(no.readonly = TRUE)
   on.exit(par(par0), add = TRUE)
 
-
-  # Deprecated arguments: ----
-
   if (is.null(which.tree) == FALSE) {
-
     warning("plot.FFTrees: 'which.tree' is deprecated. Use 'tree' instead.")
 
     tree <- which.tree
   }
 
   if (is.null(decision.names) == FALSE) {
-
     warning("plot.FFTrees: 'decision.names' is deprecated, use 'decision.labels' instead.")
 
     decision.labels <- decision.names
   }
 
-  if (is.null(stats) == FALSE){
-
+  if (is.null(stats) == FALSE) {
     warning("plot.FFTrees: 'stats' is deprecated, use either what = 'all' or what = 'tree' instead.")
 
-    if (stats) { what <- "all" } else { what <- "tree" }
+    if (stats) {
+      what <- "all"
+    } else {
+      what <- "tree"
+    }
   }
 
+  valid_what <- c(
+    "all", "default",
+    "cues", "tree", "icontree", "roc"
+  ) # as (local) constant
 
-  # Verify what: ----
-
-  valid_what <- c("all", "default",
-                  "cues", "tree", "icontree", "roc")  # as (local) constant
-
-  what <- tolower(substr(what, 1, 3))  # 4robustness
+  what <- tolower(substr(what, 1, 3)) # 4robustness
 
   if (what %in% substr(valid_what, 1, 3) == FALSE) {
-
     valid_string <- paste(valid_what, collapse = ", ")
-    valid_string_q <- sapply(strsplit(valid_string, ', '), FUN = add_quotes)
+    valid_string_q <- sapply(strsplit(valid_string, ", "), FUN = add_quotes)
 
     stop(paste0("what must be a string in c(", valid_string_q, ").", sep = ""))
   }
 
-
-  # Handle what: ----
-
   if (what == "cue") { # handle special case:
 
-    showcues(x = x, main = main, ...)  # pass key inputs + graphical parameters
+    showcues(x = x, main = main, ...) # pass key inputs + graphical parameters
 
     # Note: The argument data = data was removed from showcues(),
     #       as currently no cue accuracy statistics exist in x.
-
   }
 
-
   if (what != "cue") { # ALL else in function: what in c("all", "tree", "roc")
 
-    # Set show.parts parameters: ----
-
     if (what == "all" | what == "def") { # default:
 
       if (is.null(show.header)) {
@@ -265,7 +260,6 @@ plot.FFTrees <- function(x = NULL,
       if (is.null(show.iconguide)) {
         show.iconguide <- TRUE
       }
-
     } # if (what == "all" | "def").
 
 
@@ -292,7 +286,6 @@ plot.FFTrees <- function(x = NULL,
       if (is.null(show.iconguide)) {
         show.iconguide <- FALSE
       }
-
     } # if (what == "tre").
 
 
@@ -319,7 +312,6 @@ plot.FFTrees <- function(x = NULL,
       if (is.null(show.iconguide)) {
         show.iconguide <- FALSE
       }
-
     } # if (what == "ico").
 
 
@@ -334,69 +326,57 @@ plot.FFTrees <- function(x = NULL,
       show.top <- FALSE
 
       hlines <- FALSE
-
     } # if (what == "roc").
 
-
-    # Determine layout: ----
-
-    # Constants (currently fixed parameters):
-    show_icon_guide_legend <- FALSE
-
-    # Top, middle, and bottom:
     if (show.header & show.tree & (show.confusion | show.levels | show.roc)) {
-
-      show.top    <- TRUE
+      show.top <- TRUE
       show.middle <- TRUE
       show.bottom <- TRUE
 
       layout(matrix(1:3, nrow = 3, ncol = 1),
-             widths = c(6),
-             heights = c(1.2, 3, 1.8)
+        widths = c(6),
+        heights = c(1.2, 3, 1.8)
       )
     }
 
     # Top and middle only:
     if (show.header & show.tree & (show.confusion == FALSE & show.levels == FALSE & show.roc == FALSE)) {
-
       show.top <- TRUE
       show.middle <- TRUE
       show.bottom <- FALSE
 
       layout(matrix(1:2, nrow = 2, ncol = 1),
-             widths = c(6),
-             heights = c(1.2, 3))
+        widths = c(6),
+        heights = c(1.2, 3)
+      )
     }
 
     # Middle and bottom only:
     if (show.header == FALSE & show.tree & (show.confusion | show.levels | show.roc)) {
-
       show.top <- FALSE
       show.middle <- TRUE
       show.bottom <- TRUE
 
       layout(matrix(1:2, nrow = 2, ncol = 1),
-             widths = c(6),
-             heights = c(3, 1.8)
+        widths = c(6),
+        heights = c(3, 1.8)
       )
     }
 
     # Middle only:
     if (show.header == FALSE & show.tree & (show.confusion == FALSE & show.levels == FALSE & show.roc == FALSE)) {
-
       show.top <- FALSE
       show.middle <- TRUE
       show.bottom <- FALSE
 
       layout(matrix(1:1, nrow = 1, ncol = 1),
-             widths = c(6),
-             heights = c(3)
+        widths = c(6),
+        heights = c(3)
       )
     }
 
     # Bottom only:
     if (show.header == FALSE & show.tree == FALSE) {
-
       show.top <- FALSE
       show.middle <- FALSE
       show.bottom <- TRUE
@@ -404,30 +384,25 @@ plot.FFTrees <- function(x = NULL,
       nplots <- show.confusion + show.levels + show.roc
 
       layout(matrix(1:nplots, nrow = 1, ncol = nplots),
-             widths = c(3 * nplots),
-             heights = c(3)
+        widths = c(3 * nplots),
+        heights = c(3)
       )
     }
 
-
-    # data: ----
-
     # Note: data can be either a string "train"/"test"
     #       OR an entire data frame (of new test data):
 
     if (inherits(data, "character")) {
-
-      data <- tolower(data)  # 4robustness
+      data <- tolower(data) # 4robustness
 
       # testthat::expect_true(data %in% c("train", "test"))
-      if (!data %in% c("test", "train")){
+      if (!data %in% c("test", "train")) {
         stop("The data to plot must be 'test' or 'train'.")
       }
     }
 
 
     if (inherits(data, "data.frame")) {
-
       message("Applying FFTrees object x to new test data...")
 
       x <- fftrees_apply(x, mydata = "test", newdata = data)
@@ -435,58 +410,35 @@ plot.FFTrees <- function(x = NULL,
       message("Success, but re-assign output to x or use fftrees_apply() to globally change x")
 
       data <- "test" # in rest of this function
-
     }
 
-
-    # Extract key parameters from x: ------
-
-    # goal: ----
-
     goal <- x$params$goal
 
-    # decision.labels:
     if (is.null(decision.labels)) {
-
       if (("decision.labels" %in% names(x$params))) {
         decision.labels <- x$params$decision.labels
       } else {
         decision.labels <- c(0, 1)
       }
-
     }
 
-    # truth.labels:
     if (is.null(truth.labels)) {
-
       truth.labels <- decision.labels
-
-      # ToDo: Check for 2 cases, else use a default of c(0, 1).
-
     }
 
-    # main: ----
-
     if (is.null(main)) {
-
       if (("main" %in% names(x$params))) {
-
         if (is.null(x$params$main)) {
-
           if (show.header) {
             main <- "Data"
           } else {
             main <- ""
           }
-
         } else {
           main <- x$params$main
         }
-
       } else {
-
         if (inherits(data, "character")) {
-
           if (data == "train") {
             main <- "Data (Training)"
           }
@@ -499,60 +451,52 @@ plot.FFTrees <- function(x = NULL,
         if (inherits(data, "data.frame")) {
           main <- "Test Data"
         }
-
       } # if (("main" %in% names(x$params))).
-
     } # if (is.null(main)).
 
+    tree <- verify_tree_arg(x = x, data = data, tree = tree) # use helper (for plotting AND printing)
 
-    # tree: ----
-
-    # Verify tree input: ----
-
-    tree <- verify_tree_arg(x = x, data = data, tree = tree)  # use helper (for plotting AND printing)
-
-
-    # Get "best" tree: ----
 
     if (tree == "best.train") {
-
-      if (data == "test"){
+      if (data == "test") {
         warning("You asked for the 'best.train' tree, but data was set to 'test'. Used the best tree for 'train' data instead...")
         data <- "train"
-        if (is.null(main)) { main <- "Data (Training)" }
+        if (is.null(main)) {
+          main <- "Data (Training)"
+        }
       }
 
       # tree <- x$trees$best$train  # using current x
-      tree <- get_best_tree(x, data = "train", goal = x$params$goal)  # using helper
+      tree <- get_best_tree(x, data = "train", goal = x$params$goal) # using helper
     }
 
     if (tree == "best.test") {
-
-      if (data == "train"){
+      if (data == "train") {
         warning("You asked for the 'best.test' tree, but data was set to 'train'. Used the best tree for 'test' data instead...")
         data <- "test"
-        if (is.null(main)) { main <- "Data (Testing)" }
+        if (is.null(main)) {
+          main <- "Data (Testing)"
+        }
       }
 
       # tree <- x$trees$best$test  # using current x
-      tree <- get_best_tree(x, data = "test", goal = x$params$goal)  # using helper
+      tree <- get_best_tree(x, data = "test", goal = x$params$goal) # using helper
     }
 
-
-    # Define critical objects: ------
-
     # decision_v  <- x$trees$decisions[[data]][[tree]]$decision
-    tree_stats  <- x$trees$stats[[data]]
-    level_stats <- x$trees$level_stats[[data]][x$trees$level_stats[[data]]$tree == tree, ]
+    tree_stats <- x$trees$stats[[data]]
+
+    level_stats <- x |>
+      pluck_level_stats(data_type = data, tree = tree)
 
     # Get criterion (from object x):
-    criterion_name <- x$criterion_name  # (only ONCE)
+    criterion_name <- x$criterion_name # (only ONCE)
 
     # Compute criterion baseline/base rate:
-    if (allow_NA_crit){
+    if (allow_NA_crit) {
       crit_br <- mean(x$data[[data]][[criterion_name]], na.rm = TRUE)
     } else { # default:
-      crit_br <- mean(x$data[[data]][[criterion_name]])  # (from logical, i.e., proportion of TRUE values)
+      crit_br <- mean(x$data[[data]][[criterion_name]]) # (from logical, i.e., proportion of TRUE values)
     }
 
     n_exemplars <- nrow(x$data[[data]])
@@ -562,65 +506,14 @@ plot.FFTrees <- function(x = NULL,
 
     final_stats <- tree_stats[tree, ]
 
-
-    # Add level statistics: ----
-
     n_levels <- nrow(level_stats)
 
-    # Add marginal classification statistics to level_stats / Frequencies per level:
-
-    level_stats$hi_m <- NA  # initialize marginal freqs
-    level_stats$fa_m <- NA
-    level_stats$mi_m <- NA
-    level_stats$cr_m <- NA
-
-    for (i in 1:n_levels) {
-
-      if (i == 1) {
-        level_stats$hi_m[1] <- level_stats$hi[1]
-        level_stats$fa_m[1] <- level_stats$fa[1]
-        level_stats$mi_m[1] <- level_stats$mi[1]
-        level_stats$cr_m[1] <- level_stats$cr[1]
-      }
-
-      if (i > 1) {
-        level_stats$hi_m[i] <- level_stats$hi[i] - level_stats$hi[i - 1]
-        level_stats$fa_m[i] <- level_stats$fa[i] - level_stats$fa[i - 1]
-        level_stats$mi_m[i] <- level_stats$mi[i] - level_stats$mi[i - 1]
-        level_stats$cr_m[i] <- level_stats$cr[i] - level_stats$cr[i - 1]
-      }
-
-    } # for n_levels.
-
-    # print(level_stats)  # tree with marginal frequency values (for each level)
-
-
-    # Set plotting parameters: ----
-
-    # Label sizes:
-
-    # print(paste0("par('cex') = ", par("cex")))  # Note: Value varies from .66 to 1
-
-    # Sizes not set by user:
-    f_cex <- 1  # cex scaling factor
+    f_cex <- 1 # cex scaling factor
 
     decision_node_cex <- 4 * f_cex
-    exit_node_cex     <- 4 * f_cex
-    panel_title_cex   <- 2 * f_cex
-
-    # Set by user arguments:
+    exit_node_cex <- 4 * f_cex
+    panel_title_cex <- 2 * f_cex
 
-    # Cue label size:
-    if (is.null(cue.cex)) {
-      cue.cex <- c(1.50, 1.50, 1.25, 1, 1, 1)
-    } else {
-      if (length(cue.cex) < 6) {
-        cue.cex <- rep(cue.cex, length.out = 6)
-      }
-    }
-    # print(cue.cex)  # 4debugging
-
-    # Break label size:
     if (is.null(threshold.cex)) {
       threshold.cex <- c(1.50, 1.50, 1.25, 1, 1, 1)
     } else {
@@ -628,7 +521,6 @@ plot.FFTrees <- function(x = NULL,
         threshold.cex <- rep(threshold.cex, length.out = 6)
       }
     }
-    # print(threshold.cex)  # 4debugging
 
     # Panel parameters:
     panel_line_lwd <- 1
@@ -636,8 +528,8 @@ plot.FFTrees <- function(x = NULL,
     panel_line_lty <- 1
 
     # Ball parameters:
-    ball_col <- c(gray(0), gray(0))  # = black
-    ball_bg  <- c(gray(1), gray(1))  # = white
+    ball_col <- c(gray(0), gray(0)) # = black
+    ball_bg <- c(gray(1), gray(1)) # = white
     ball_pch <- c(21, 24)
     ball_cex <- c(1, 1)
 
@@ -647,9 +539,7 @@ plot.FFTrees <- function(x = NULL,
     max_label_length <- 100
     # def_par <- par(no.readonly = TRUE)  # is NOT used anywhere?
 
-    ball_box_width   <- 10
-    label_box_height <-  2
-    label_box_width  <-  5
+    ball_box_width <- 10
 
     # Cue labels:
     if (is.null(cue.labels)) {
@@ -663,40 +553,31 @@ plot.FFTrees <- function(x = NULL,
     segment_lty <- 1
     segment_lwd <- 1
 
-    # continue_segment_lwd <- 1  # is NOT used anywhere?
-    # continue_segment_lty <- 1  # is NOT used anywhere?
-
-    # exit_segment_lwd <- 1  # is NOT used anywhere?
-    # exit_segment_lty <- 1  # is NOT used anywhere?
-
-
     # Define plotting_parameters_df:
     if (show.top & show.middle & show.bottom) { # plot "all":
 
       plotting_parameters_df <- data.frame(
         n_levels = 1:6,
-        plot_height = c(10, 12, 15, 19, 23, 27),        # Note: use default, +2 for n_levels == 6
-        plot_width  = c(14, 16, 20, 24, 28, 34) * 1.0,  # Note: use default, +2 for n_levels == 6
+        plot_height = c(10, 12, 15, 19, 23, 27), # Note: use default, +2 for n_levels == 6
+        plot_width = c(14, 16, 20, 24, 28, 34) * 1.0, # Note: use default, +2 for n_levels == 6
         label_box_text_cex = cue.cex,
         break_label_cex = threshold.cex
       )
-
-    } else if ((show.top == FALSE) & show.middle & (show.bottom == FALSE)) {  # only "ico" or "tree":
+    } else if ((show.top == FALSE) & show.middle & (show.bottom == FALSE)) { # only "ico" or "tree":
 
       plotting_parameters_df <- data.frame(
         n_levels = 1:6,
         plot_height = c(10, 12, 15, 19, 23, 25),
-        plot_width  = c(14, 16, 20, 24, 28, 32) * 0.80,  # stretch wider (but not too wide for n.per.icon = 1)
+        plot_width = c(14, 16, 20, 24, 28, 32) * 0.80, # stretch wider (but not too wide for n_per_icon = 1)
         label_box_text_cex = cue.cex,
         break_label_cex = threshold.cex
       )
-
     } else { # default:
 
       plotting_parameters_df <- data.frame(
         n_levels = 1:6,
         plot_height = c(10, 12, 15, 19, 23, 25),
-        plot_width  = c(14, 16, 20, 24, 28, 32) * 1,  # stretch to default width
+        plot_width = c(14, 16, 20, 24, 28, 32) * 1, # stretch to default width
         label_box_text_cex = cue.cex,
         break_label_cex = threshold.cex
       )
@@ -704,1471 +585,1456 @@ plot.FFTrees <- function(x = NULL,
 
     # local variables:
     if (n_levels < 6) {
-
       label_box_text_cex <- plotting_parameters_df$label_box_text_cex[n_levels]
       break_label_cex <- plotting_parameters_df$break_label_cex[n_levels]
       plot_height <- plotting_parameters_df$plot_height[n_levels]
       plot_width <- plotting_parameters_df$plot_width[n_levels]
-
     } else { # n_levels >= 6:
 
       label_box_text_cex <- plotting_parameters_df$label_box_text_cex[6]
       break_label_cex <- plotting_parameters_df$break_label_cex[6]
       plot_height <- plotting_parameters_df$plot_height[6]
       plot_width <- plotting_parameters_df$plot_width[6]
-
     }
 
-
-    # Colors: ----
-
     col_exit_node_bg <- "white"
 
-    # error.colfun <- circlize::colorRamp2(c(0, 50, 100),
-    #                            colors = c("white", "red", "black"))
-    #
-    # correct.colfun <-  circlize::colorRamp2(c(0, 50, 100),
-    #                            colors = c("white", "green", "black"))
-    #
-    # col_error_bg <- scales::alpha(error.colfun(35), .8)
-    # col_error_border <-  scales::alpha(error.colfun(65), .9)
-    # col_correct_bg <- scales::alpha(correct.colfun(35), .8)
-    # col_correct_border <-  scales::alpha(correct.colfun(65), .9)
-
     if (!grayscale) {
-
       col_error_bg <- "#FF7352CC"
       col_error_border <- "#AD1A0AE6"
       col_correct_bg <- "#89FF6FCC"
       col_correct_border <- "#24AB18E6"
-
     } else {
-
       # Grayscale colors
 
       col_error_bg <- gray(.1)
       col_error_border <- gray(0)
       col_correct_bg <- gray(1)
       col_correct_border <- gray(0)
-
     }
 
-          # max_cex <- 6  # is NOT used anywhere?
-          # min_cex <- 1  # is NOT used anywhere?
-
-          exit_node_pch <- 21
-
-          decision_node_pch <- NA_integer_
-
-
-          # Balls: ----
-
-          ball_loc <- "variable"
-
-          if (n_levels == 3) {
-            ball_box_width <- 14
-          }
-
-          if (n_levels == 4) {
-            ball_box_width <- 18
-          }
-
-          ball_box_height      <- 2.5
-          ball_box_horiz_shift <- 10
-          ball_box_vert_shift  <- -1
-          ball_box_max_shift_p <- .9
-          ball_box_min_shift_p <- .4
-
-          ball_box_fixed_x_shift <- c(ball_box_min_shift_p * plot_width, ball_box_max_shift_p * plot_width)
-
-          # Determine N per ball:
-          if (is.null(n.per.icon)) {
-
-            max_n_side <- max(c(n_pos_cases, n_neg_cases))
-
-            i <- max_n_side / c(1, 5, 10^(1:10))
-            i[i > 50] <- 0
-
-            n.per.icon <- c(1, 5, 10^(1:10))[which(i == max(i))]
-
-          }
-
-          noise_ball_pch  <- ball_pch[1]
-          signal_ball_pch <- ball_pch[2]
-          noise_ball_col  <- ball_col[1]
-          signal_ball_col <- ball_col[2]
-          noise_ball_bg   <- ball_bg[1]
-          signal_ball_bg  <- ball_bg[2]
-
-
-          # Arrows: ----
-
-          arrow_lty <- 1
-          arrow_lwd <- 1
-          arrow_length      <- 2.50
-          arrow_head_length <-  .08
-          arrow_col <- gray(0) # = black
-
-
-          # Final stats: ----
-
-          # spec_circle_x   <- .40  # is NOT used anywhere?
-          # dprime_circle_x <- .50  # is NOT used anywhere?
-          # sens_circle_x   <- .60  # is NOT used anywhere?
-
-          # stat_circle_y   <- .30  # is NOT used anywhere?
-
-          # sens_circle_col   <- "green"  # is NOT used anywhere?
-          # spec_circle_col   <- "red"    # is NOT used anywhere?
-          # dprime_circle_col <- "blue"   # is NOT used anywhere?
-          # stat_outer_circle_col <- gray(.50)  # is NOT used anywhere?
-
-
-          # 1: Initial Frequencies: ------
-
-          # Parameters:
-
-          if (show.top) {
-
-            par(mar = c(0, 0, 1, 0))
-
-            # Prepare plot:
-            plot(1,
-                 xlim = c(0, 1), ylim = c(0, 1), bty = "n", type = "n",
-                 xlab = "", ylab = "", yaxt = "n", xaxt = "n"
-            )
-
-            # 1. Title: ----
-
-            par(xpd = TRUE)
-
-            # (a) lines:
-            if (hlines) {
-
-              segments(0, .95, 1, .95, col = col_panel_line, lwd = panel_line_lwd, lty = panel_line_lty)  # top hline
-
-              x_dev <- get_x_dev(main)
-              y_dev <- .20
-              rect((.50 - x_dev), (1 - y_dev), (.50 + x_dev), (1 + y_dev), col = "white", border = NA)  # title background
-
-            }
-
-            # (b) label:
-            text(x = .50, y = .96, main, cex = panel_title_cex, ...)  # title 1 (top): main
-
-
-            # 2. Data info: ----
-
-            # (a) N and labels:
-            text(x = .50, y = .78, paste("N = ", prettyNum(n_exemplars, big.mark = ","), "", sep = ""), cex = 1.25) # N
-            text(.50, .63, paste(truth.labels[1], sep = ""), pos = 2, cex = 1.2, adj = 1)  # 1: False
-            text(.50, .63, paste(truth.labels[2], sep = ""), pos = 4, cex = 1.2, adj = 0)  # 2: True
-
-            # (b) Show balls:
-            n_true_pos <- with(final_stats, hi + mi)
-            n_true_neg <- with(final_stats, fa + cr)
-
-            add_balls(
-              x_lim = c(.33, .67),
-              y_lim = c(.12, .52),
-              n_vec = c(n_true_neg, n_true_pos),
-              pch_vec = c(noise_ball_pch, signal_ball_pch),
-              bg_vec = c(noise_ball_bg, signal_ball_bg),
-              col_vec = c(noise_ball_col, signal_ball_col),
-              ball_cex = ball_cex,
-              upper_text_adj = 2,
-              n_per_icon = n.per.icon
-            )
-
-            # (c) n.per.icon legend 1 (top):
-
-            # show_icon_guide_legend <- TRUE  # 4debugging
-
-            if (show_icon_guide_legend){
-
-              text(.98, 0, labels = paste("Showing ", n.per.icon, " cases per icon:", sep = ""), pos = 2)
-              points(.98, 0, pch = noise_ball_pch,  cex = ball_cex)
-              points(.99, 0, pch = signal_ball_pch, cex = ball_cex)
-
-            } # if (show_icon_guide_legend).
-
-
-            par(xpd = FALSE)
-
-
-            # 3. Add p_signal and p_noise levels: -----
-
-            signal_p <- crit_br  # criterion baseline/base rate (from above)
-            noise_p  <- (1 - signal_p)
-
-            p_rect_ylim <- c(.10, .60)
-
-
-            # (a) p_signal level (on right): ----
-
-            text(
-              x = .80, y = p_rect_ylim[2],
-              labels = paste("p(", truth.labels[2], ")", sep = ""),
-              pos = 3, cex = 1.2
-            )
-
-            # Filling:
-            rect(.775, p_rect_ylim[1],
-                 .825, p_rect_ylim[1] + signal_p * diff(p_rect_ylim),
-                 col = gray(.50, .25), border = NA
-            )
-
-            # Filltop:
-            segments(.775, p_rect_ylim[1] + signal_p * diff(p_rect_ylim),
-                     .825, p_rect_ylim[1] + signal_p * diff(p_rect_ylim),
-                     lwd = 1
-            )
-
-            # Outline:
-            rect(.775, p_rect_ylim[1],
-                 .825, p_rect_ylim[2],
-                 lwd = 1
-            )
-
-            if (signal_p < .0001) {
-              signal_p_text <- "<1%"
-            } else {
-              signal_p_text <- paste(round(signal_p * 100, 0), "%", sep = "")
-            }
-
-            text(.825, p_rect_ylim[1] + signal_p * diff(p_rect_ylim),
-                 labels = signal_p_text,
-                 pos = 4, cex = 1.2
-            )
-
-
-            # (b) p_noise level (on left): ----
-
-            text(
-              x = .20, y = p_rect_ylim[2],
-              labels = paste("p(", truth.labels[1], ")", sep = ""),
-              pos = 3, cex = 1.2
-            )
-
-
-            rect(.175, p_rect_ylim[1], .225, p_rect_ylim[1] + noise_p * diff(p_rect_ylim),
-                 col = gray(.50, .25), border = NA
-            )
-
-            # Filltop:
-            segments(.175, p_rect_ylim[1] + noise_p * diff(p_rect_ylim),
-                     .225, p_rect_ylim[1] + noise_p * diff(p_rect_ylim),
-                     lwd = 1
-            )
-
-            # Outline:
-            rect(.175, p_rect_ylim[1], .225, p_rect_ylim[2],
-                 lwd = 1
-            )
-
-            if (noise_p < .0001) {
-              noise_p_text <- "<0.01%"
-            } else {
-              noise_p_text <- paste(round(noise_p * 100, 0), "%", sep = "")
-            }
-
-            text(.175, p_rect_ylim[1] + noise_p * diff(p_rect_ylim),
-                 labels = noise_p_text,
-                 pos = 2, cex = 1.2
-            )
-
-          } # if (show.top).
-
-
-          # 2. Main TREE: ------
-
-          if (show.middle) {
-
-            if ((show.top == FALSE) & (show.bottom == FALSE)) {
-              par(mar = c(3, 3, 3, 3) + .1)
-            } else {
-              par(mar = c(0, 0, 0, 0))
-            }
-
-            par(xpd = TRUE)
-
-            # Prepare plot:
-            plot(1,
-                 xlim = c(-plot_width, plot_width),
-                 ylim = c(-plot_height, 0),
-                 type = "n", bty = "n",
-                 xaxt = "n", yaxt = "n",
-                 ylab = "", xlab = ""
-            )
-
-
-            # Middle title: ----
-
-            if (show.top | show.bottom) {
-
-              if (hlines) {
-                x_dev <- .28  # scaling factor, rather than difference
-                segments(-plot_width, 0, -plot_width * x_dev, 0, col = col_panel_line, lwd = panel_line_lwd, lty = panel_line_lty)
-                segments( plot_width, 0,  plot_width * x_dev, 0, col = col_panel_line, lwd = panel_line_lwd, lty = panel_line_lty)
-              }
-
-              if (is.null(label.tree)) {
-                label.tree <- paste("FFT #", tree, " (of ", x$trees$n, ")", sep = "")
-              }
-
-              text(x = 0, y = 0, label.tree, cex = panel_title_cex, ...)  # title 2 (middle): (a) tree label
-
-            } # if (show.top | show.bottom).
-
-            if (show.top == FALSE & show.bottom == FALSE) {
-
-              if (is.null(main) & is.null(x$params$main)) {
-                main <- ""
-              }
-
-              mtext(text = main, side = 3, cex = panel_title_cex, ...)  # title 2 (middle): (b) main label
-
-            } # if (show.top == FALSE & show.bottom == FALSE).
-
-
-            # Icon guide: ------
-
-            if (show.iconguide) {
-
-              # Parameters:
-              if (what == "ico") {
-
-                f_x <- 1.2  # scaling factor (to stretch in x-dim)
-                f_y <- 0.8  # scaling factor (to shift up)
-
-              } else { # default scaling factors:
-
-                f_x <- 1
-                f_y <- 1
-
-              }
-
-              get_exit_word <- get_exit_word(data)  # either 'train':'decide' or 'test':'predict'
-
-
-              # (a) Noise panel (on left): ----
-
-              # Parameters:
-
-              if (what == "ico"){
-                leg_head_y <- .02
-                leg_ball_y <- .14
-              } else {
-                leg_head_y <- .05
-                leg_ball_y <- .15
-              }
-
-
-              # Heading:
-              text(-plot_width  * .60 * f_x,
-                   -plot_height * leg_head_y * f_y,
-                   paste(get_exit_word, decision.labels[1], sep = " "),
-                   cex = 1.2, font = 3
-              )
-
-              # Noise balls:
-              points(c(-plot_width  * .70, -plot_width  * .50) * f_x,
-                     c(-plot_height * leg_ball_y, -plot_height * leg_ball_y) * f_y,
-                     pch = c(noise_ball_pch, signal_ball_pch),
-                     bg = c(col_correct_bg, col_error_bg),
-                     col = c(col_correct_border, col_error_border),
-                     cex = ball_cex * 1.5
-              )
-
-              # Labels:
-              text(c(-plot_width  * .70, -plot_width  * .50) * f_x,
-                   c(-plot_height * leg_ball_y, -plot_height * leg_ball_y) * f_y,
-                   labels = c("Correct\nRejection", "Miss"),
-                   pos = c(2, 4), offset = .80, cex = 1
-              )
-
-
-
-              # (b) Signal panel (on right): ----
-
-              # Heading:
-              text( plot_width  * .60 * f_x,
-                    -plot_height * leg_head_y * f_y,
-                    paste(get_exit_word, decision.labels[2], sep = " "),
-                    cex = 1.2, font = 3
-              )
-
-              # Signal balls:
-              points(c(plot_width   * .50,  plot_width  * .70 ) * f_x,
-                     c(-plot_height * leg_ball_y, -plot_height * leg_ball_y) * f_y,
-                     pch = c(noise_ball_pch, signal_ball_pch),
-                     bg = c(col_error_bg, col_correct_bg),
-                     col = c(col_error_border, col_correct_border),
-                     cex = ball_cex * 1.5
-              )
-
-              # Labels:
-              text(c( plot_width  * .50,  plot_width  * .70) * f_x,
-                   c(-plot_height * leg_ball_y, -plot_height * leg_ball_y) * f_y,
-                   labels = c("False\nAlarm", "Hit"),
-                   pos = c(2, 4), offset = .80, cex = 1
-              )
+    # max_cex <- 6  # is NOT used anywhere?
+    # min_cex <- 1  # is NOT used anywhere?
 
+    exit_node_pch <- 21
 
-              # (c) Additional lines (below icon guide): ----
-              if (what == "ico" & hlines) {
+    decision_node_pch <- NA_integer_
 
-                x_hline <-  plot_width  * 1.0 * f_x
-                y_hline <- -plot_height * .22 * f_y
+    ball_loc <- "variable"
 
-                segments(-x_hline, y_hline, x_hline, y_hline, col = col_panel_line, lwd = panel_line_lwd, lty = panel_line_lty)
-                rect(-x_hline * .33, (y_hline - .5), x_hline * .33, (y_hline + .5), col = "white", border = NA)
-              }
-
-
-              # (d) n.per.icon legend 2 (middle): ----
-
-              if (what == "ico") { show_icon_guide_legend <- TRUE } # special case
-
-              if (show_icon_guide_legend){
-
-                if (what == "ico") { # special case:
-
-                  x_s2 <- plot_width
-                  x_s1 <- plot_width - .80     # left of default
-                  y_s1 <- plot_height * -1.10  # lower than default
-
-                } else { # defaults:
-
-                  x_s2 <- plot_width
-                  x_s1 <- plot_width - .40
-                  y_s1 <- plot_height * -1
-
-                }
-
-                text(x_s1, y_s1, labels = paste("Showing ", n.per.icon, " cases per icon:", sep = ""), pos = 2, cex = ball_cex)
-                points(x_s1, y_s1, pch = noise_ball_pch,  cex = ball_cex)
-                points(x_s2, y_s1, pch = signal_ball_pch, cex = ball_cex)
-
-              } # if (show_icon_guide_legend).
-
-            } # if (show.iconguide).
-
-            par(xpd = FALSE)
-
-
-            # Plot main TREE: ------
-
-            # Set initial subplot center:
-            subplot_center <- c(0, -4)
-
-            # Loop over levels: ------
-            for (level_i in 1:min(c(n_levels, 6))) {
-
-              # Cue label:
-              cur_cue <- cue.labels[level_i]
-
-              # Get stats for current level:
-              hi_i <- level_stats$hi_m[level_i]
-              fa_i <- level_stats$fa_m[level_i]
-              mi_i <- level_stats$mi_m[level_i]
-              cr_i <- level_stats$cr_m[level_i]
-
-
-              # Top: If level_i == 1, draw top textbox: ----
-
-              if (level_i == 1) {
-
-                rect(subplot_center[1] - label_box_width / 2,
-                     subplot_center[2] + 2 - label_box_height / 2,
-                     subplot_center[1] + label_box_width / 2,
-                     subplot_center[2] + 2 + label_box_height / 2,
-                     col = "white",
-                     border = "black"
-                )
-
-                points(
-                  x = subplot_center[1],
-                  y = subplot_center[2] + 2,
-                  cex = decision_node_cex,
-                  pch = decision_node_pch
-                )
-
-                text(
-                  x = subplot_center[1],
-                  y = subplot_center[2] + 2,
-                  labels = cur_cue,
-                  cex = label_box_text_cex  # WAS: get_label_cex(cur_cue, label_box_text_cex = label_box_text_cex)
-                )
-
-              } # if (level_i == 1).
-
-
-              # Left (Noise) classification / New level: ----
-
-              # Exit node on 0 / FALSE / noise / left: ----
-
-              # if (level_stats$exit[level_i] %in% c(0, .5) | paste(level_stats$exit[level_i]) %in% c("0", ".5")) {
-              if ( (level_stats$exit[level_i] %in% exit_types[c(1, 3)]) | (paste(level_stats$exit[level_i]) %in% paste(exit_types[c(1, 3)], collapse = ", ")) ) {
-
-                segments(subplot_center[1],
-                         subplot_center[2] + 1,
-                         subplot_center[1] - 2,
-                         subplot_center[2] - 2,
-                         lty = segment_lty,
-                         lwd = segment_lwd
-                )
-
-                arrows(
-                  x0 = subplot_center[1] - 2,
-                  y0 = subplot_center[2] - 2,
-                  x1 = subplot_center[1] - 2 - arrow_length,
-                  y1 = subplot_center[2] - 2,
-                  lty = arrow_lty,
-                  lwd = arrow_lwd,
-                  col = arrow_col,
-                  length = arrow_head_length
-                )
-
-                # Decision text:
-
-                if (decision.cex > 0) {
-
-                  text(
-                    x = subplot_center[1] - 2 - arrow_length * .7,
-                    y = subplot_center[2] - 2.2,
-                    labels = decision.labels[1],
-                    pos = 1, font = 3, cex = decision.cex
-                  )
-
-                }
-
-                if (ball_loc == "fixed") {
-
-                  ball_x_lim <- c(-max(ball_box_fixed_x_shift), -min(ball_box_fixed_x_shift))
-
-                  ball_y_lim <- c(
-                    subplot_center[2] + ball_box_vert_shift - ball_box_height / 2,
-                    subplot_center[2] + ball_box_vert_shift + ball_box_height / 2
-                  )
-
-                }
-
-                if (ball_loc == "variable") {
-
-                  ball_x_lim <- c(
-                    subplot_center[1] - ball_box_horiz_shift - ball_box_width / 2,
-                    subplot_center[1] - ball_box_horiz_shift + ball_box_width / 2
-                  )
-
-                  ball_y_lim <- c(
-                    subplot_center[2] + ball_box_vert_shift - ball_box_height / 2,
-                    subplot_center[2] + ball_box_vert_shift + ball_box_height / 2
-                  )
-
-                }
-
-                if ((max(c(cr_i, mi_i), na.rm = TRUE) > 0) & (show.icons == TRUE)) {
-
-                  add_balls(
-                    x_lim = ball_x_lim,
-                    y_lim = ball_y_lim,
-                    n_vec = c(cr_i, mi_i),
-                    pch_vec = c(noise_ball_pch, signal_ball_pch),
-                    ball_cex = ball_cex,
-                    # bg_vec = c(noise_ball_bg, signal_ball_bg),
-                    bg_vec = c(col_correct_bg, col_error_bg),
-                    col_vec = c(col_correct_border, col_error_border),
-                    freq_text = TRUE,
-                    n_per_icon = n.per.icon
-                  )
-
-                }
-
-                # level break label:
-                pos_dir_symbol <- c("<=", "<", "=", "!=", ">", ">=")[which(level_stats$direction[level_i] == c(">", ">=", "!=", "=", "<=", "<"))]
-                neg_dir_symbol <- c("<=", "<", "=", "!=", ">", ">=")[which(level_stats$direction[level_i] == c("<=", "<", "=", "!=", ">", ">="))]
-
-                text_outline(
-                  x = subplot_center[1] - 1,
-                  y = subplot_center[2],
-                  labels = paste(pos_dir_symbol, " ", level_stats$threshold[level_i], sep = ""),
-                  pos = 2, cex = break_label_cex, r = .1
-                )
-
-                points(
-                  x = subplot_center[1] - 2,
-                  y = subplot_center[2] - 2,
-                  pch = exit_node_pch,
-                  cex = exit_node_cex,
-                  bg = col_exit_node_bg
-                )
-
-                text(
-                  x = subplot_center[1] - 2,
-                  y = subplot_center[2] - 2,
-                  labels = substr(decision.labels[1], 1, 1)
-                )
-
-              } # if (exit node on left).
-
-
-              # New level on 1 / TRUE / signal / right: ----
-
-              # if ((level_stats$exit[level_i] %in% c(1)) | (paste(level_stats$exit[level_i]) %in% c("1"))) {
-              if ( (level_stats$exit[level_i] %in% exit_types[c(2)]) | (paste(level_stats$exit[level_i]) %in% paste(exit_types[c(2)], collapse = ", ")) ) {
-
-                segments(subplot_center[1],
-                         subplot_center[2] + 1,
-                         subplot_center[1] - 2,
-                         subplot_center[2] - 2,
-                         lty = segment_lty,
-                         lwd = segment_lwd
-                )
-
-                rect(subplot_center[1] - 2 - label_box_width / 2,
-                     subplot_center[2] - 2 - label_box_height / 2,
-                     subplot_center[1] - 2 + label_box_width / 2,
-                     subplot_center[2] - 2 + label_box_height / 2,
-                     col = "white",
-                     border = "black"
-                )
-
-                if (level_i < 6) {
-
-                  text(
-                    x = subplot_center[1] - 2,
-                    y = subplot_center[2] - 2,
-                    labels = cue.labels[level_i + 1],
-                    cex = label_box_text_cex
-                  )
-
-                } else {
-
-                  text(
-                    x = subplot_center[1] - 2,
-                    y = subplot_center[2] - 2,
-                    labels = paste0("+ ", n_levels - 6, " More"),
-                    cex = label_box_text_cex,
-                    font = 3
-                  )
-
-                }
-
-              } # if (new level on right).
-
-
-              # Right (Signal) classification / New level: ----
-
-              # Exit node on 1 / TRUE / signal / right: ----
-
-              # if ((level_stats$exit[level_i] %in% c(1, .5)) | (paste(level_stats$exit[level_i]) %in% c("1", ".5"))) {
-              if ( (level_stats$exit[level_i] %in% exit_types[c(2, 3)]) | (paste(level_stats$exit[level_i]) %in% paste(exit_types[c(2, 3)], collapse = ", ")) ) {
-
-                segments(subplot_center[1],
-                         subplot_center[2] + 1,
-                         subplot_center[1] + 2,
-                         subplot_center[2] - 2,
-                         lty = segment_lty,
-                         lwd = segment_lwd
-                )
-
-                arrows(
-                  x0 = subplot_center[1] + 2,
-                  y0 = subplot_center[2] - 2,
-                  x1 = subplot_center[1] + 2 + arrow_length,
-                  y1 = subplot_center[2] - 2,
-                  lty = arrow_lty,
-                  lwd = arrow_lwd,
-                  col = arrow_col,
-                  length = arrow_head_length
-                )
-
-                # Decision text:
-
-                if (decision.cex > 0) {
-                  text(
-                    x = subplot_center[1] + 2 + arrow_length * .7,
-                    y = subplot_center[2] - 2.2,
-                    labels = decision.labels[2],
-                    pos = 1,
-                    font = 3,
-                    cex = decision.cex
-                  )
-
-                }
-
-                if (ball_loc == "fixed") {
-
-                  ball_x_lim <- c(min(ball_box_fixed_x_shift), max(ball_box_fixed_x_shift))
-                  ball_y_lim <- c(
-                    subplot_center[2] + ball_box_vert_shift - ball_box_height / 2,
-                    subplot_center[2] + ball_box_vert_shift + ball_box_height / 2
-                  )
-
-                }
-
-                if (ball_loc == "variable") {
-
-                  ball_x_lim <- c(
-                    subplot_center[1] + ball_box_horiz_shift - ball_box_width / 2,
-                    subplot_center[1] + ball_box_horiz_shift + ball_box_width / 2
-                  )
-
-                  ball_y_lim <- c(
-                    subplot_center[2] + ball_box_vert_shift - ball_box_height / 2,
-                    subplot_center[2] + ball_box_vert_shift + ball_box_height / 2
-                  )
-
-                }
-
-                if ((max(c(fa_i, hi_i), na.rm = TRUE) > 0) & (show.icons == TRUE)) {
-
-                  add_balls(
-                    x_lim = ball_x_lim,
-                    y_lim = ball_y_lim,
-                    n_vec = c(fa_i, hi_i),
-                    pch_vec = c(noise_ball_pch, signal_ball_pch),
-                    ball_cex = ball_cex,
-                    # bg_vec = c(noise_ball_bg, signal_ball_bg),
-                    bg_vec = c(col_error_bg, col_correct_bg),
-                    col_vec = c(col_error_border, col_correct_border),
-                    freq_text = TRUE,
-                    n_per_icon = n.per.icon
-                  )
-
-                }
-
-                # level break label:
-                dir_symbol <- c("<=", "<", "=", "!=", ">", ">=")  # as (local) constant
-
-                pos_dir_symbol <- dir_symbol[which(level_stats$direction[level_i] == c("<=", "<", "=", "!=", ">", ">="))]
-                neg_dir_symbol <- dir_symbol[which(level_stats$direction[level_i] == rev(c("<=", "<", "=", "!=", ">", ">=")))]
-
-
-                text_outline(subplot_center[1] + 1,
-                             subplot_center[2],
-                             labels = paste(pos_dir_symbol, " ", level_stats$threshold[level_i], sep = ""),
-                             pos = 4, cex = break_label_cex, r = .1
-                )
-
-                points(
-                  x = subplot_center[1] + 2,
-                  y = subplot_center[2] - 2,
-                  pch = exit_node_pch,
-                  cex = exit_node_cex,
-                  bg = col_exit_node_bg
-                )
-
-                text(
-                  x = subplot_center[1] + 2,
-                  y = subplot_center[2] - 2,
-                  labels = substr(decision.labels[2], 1, 1)
-                )
-
-              } # if (exit node on right).
-
-
-              # New level on 0 / FALSE / noise / left: ----
-
-              # if (level_stats$exit[level_i] %in% 0 | paste(level_stats$exit[level_i]) %in% c("0")) {
-              if ( (level_stats$exit[level_i] %in% exit_types[c(1)]) | (paste(level_stats$exit[level_i]) %in% paste(exit_types[c(1)], collapse = ", ")) ) {
-
-                segments(subplot_center[1],
-                         subplot_center[2] + 1,
-                         subplot_center[1] + 2,
-                         subplot_center[2] - 2,
-                         lty = segment_lty,
-                         lwd = segment_lwd
-                )
-
-                if (level_i < 6) {
-
-                  rect(subplot_center[1] + 2 - label_box_width / 2,
-                       subplot_center[2] - 2 - label_box_height / 2,
-                       subplot_center[1] + 2 + label_box_width / 2,
-                       subplot_center[2] - 2 + label_box_height / 2,
-                       col = "white",
-                       border = "black"
-                  )
-
-                  text(
-                    x = subplot_center[1] + 2,
-                    y = subplot_center[2] - 2,
-                    labels = cue.labels[level_i + 1],
-                    cex = label_box_text_cex
-                  )
-
-                } else {
-
-                  rect(subplot_center[1] + 2 - label_box_width / 2,
-                       subplot_center[2] - 2 - label_box_height / 2,
-                       subplot_center[1] + 2 + label_box_width / 2,
-                       subplot_center[2] - 2 + label_box_height / 2,
-                       col = "white",
-                       border = "black", lty = 2
-                  )
-
-                  text(
-                    x = subplot_center[1] + 2,
-                    y = subplot_center[2] - 2,
-                    labels = paste0("+ ", n_levels - 6, " More"),
-                    cex = label_box_text_cex,
-                    font = 3
-                  )
-                }
-
-              } # if (new level on right).
-
-
-              # Update plot center: ----
-
-              # if (identical(paste(level_stats$exit[level_i]), "0")) { # 0 / FALSE / noise / left:
-              if (identical(paste(level_stats$exit[level_i]), paste0(exit_types[1]))) {
-
-                subplot_center <- c(
-                  subplot_center[1] + 2,
-                  subplot_center[2] - 4
-                )
-              } # if (identical exit 0 / left etc.
-
-              # if (identical(paste(level_stats$exit[level_i]), "1")) { # 1 / TRUE / signal / right:
-              if (identical(paste(level_stats$exit[level_i]), paste0(exit_types[2]))) {
-
-                subplot_center <- c(
-                  subplot_center[1] - 2,
-                  subplot_center[2] - 4
-                )
-
-              } # if (identical exit 1 / right etc.
-
-            } # for (level_i etc. loop.
-
-          } # if (show.middle).
-
-
-          # 3. Cumulative performance: ----
-
-          if (show.bottom == TRUE) { # obtain tree statistics:
-
-            fft_sens_vec <- tree_stats$sens
-            fft_spec_vec <- tree_stats$spec
-
-            # General plotting space: ----
-
-            # Parameters:
-            header_y <- 1.0
-            subheader_y <- .925
-
-            header_cex <- 1.10
-            subheader_cex <- .90
-
-            par(mar = c(0, 0, 2, 0))
-
-            plot(1,
-                 xlim = c(0, 1), ylim = c(0, 1),
-                 bty = "n", type = "n",
-                 xlab = "", ylab = "",
-                 yaxt = "n", xaxt = "n"
-            )
-
-
-            if (what != "roc"){
-
-              # Set par:
-              par(xpd = TRUE)
-
-              # Bottom title: ----
-
-              if (hlines) {
-
-                segments(0, 1.1, 1, 1.1, col = col_panel_line, lwd = panel_line_lwd, lty = panel_line_lty)
-
-                x_dev <- .20
-                rect((.50 - x_dev), 1, (.50 + x_dev), 1.2, col = "white", border = NA) # label background
-              }
-
-              # Bottom label:
-              if (is.null(label.performance)) { # user argument not set:
-
-                if (data == "train") {
-                  label.performance <- "Accuracy (Training)"
-                }
-                if (data == "test") {
-                  label.performance <- "Accuracy (Testing)"
-                }
-
-              }
-
-              text(x = .50, y = 1.1, labels = label.performance, cex = panel_title_cex, ...)  # title 3 (bottom): Performance
-
-              par(xpd = FALSE)
-
-            } # if (what != "roc").
-
-
-            # Level parameters:
-            level_height_max <- .65
-            level_width    <- .05
-            level_center_y <- .45
-            # level_bottom <- .1
-            level_bottom   <- level_center_y - (level_height_max / 2)
-            level_top      <- level_center_y + (level_height_max / 2)
-
-            # Get either bacc OR wacc (based on sens.w):
-            sens.w <- x$params$sens.w
-            bacc_wacc <- get_bacc_wacc(sens = final_stats$sens, spec = final_stats$spec, sens.w = sens.w)
-            bacc_wacc_name <- names(bacc_wacc)
-
-            # Set labels, values, and locations (as df):
-            lloc <- data.frame(
-              element = c("classtable", "mcu", "pci", "sens", "spec", "acc", bacc_wacc_name, "roc"),
-              long_name = c("Classification Table", "mcu", "pci", "sens", "spec", "acc", bacc_wacc_name, "ROC"),  # used by add_level() helper function
-              center_x = c(.18, seq(.35, .65, length.out = 6), .85),
-              center_y = rep(level_center_y, 8),
-              width  = c(.20, rep(level_width, 6), .20),
-              height = c(.65, rep(level_height_max, 6), .65),
-              value = c(NA,
-                        abs(final_stats$mcu - 5) / (abs(1 - 5)), final_stats$pci,
-                        final_stats$sens, final_stats$spec,
-                        with(final_stats, (cr + hi) / n), bacc_wacc, NA),
-              value_name = c(NA,
-                             round(final_stats$mcu, 1), pretty_dec(final_stats$pci),     # used by add_level() helper function
-                             pretty_dec(final_stats$sens), pretty_dec(final_stats$spec),
-                             pretty_dec(final_stats$acc), pretty_dec(bacc_wacc), NA)
-            )
-            # print(lloc)  # 4debugging
-
-
-            # Classification table: ----
-
-            if (show.confusion) {
-
-              # Parameters:
-              classtable_lwd <- 1
-
-              # x/y coordinates:
-              final_classtable_x <- c(lloc$center_x[lloc$element == "classtable"] - lloc$width[lloc$element  == "classtable"] / 2, lloc$center_x[lloc$element == "classtable"] + lloc$width[lloc$element  == "classtable"] / 2)
-              final_classtable_y <- c(lloc$center_y[lloc$element == "classtable"] - lloc$height[lloc$element == "classtable"] / 2, lloc$center_y[lloc$element == "classtable"] + lloc$height[lloc$element == "classtable"] / 2)
-
-              rect(final_classtable_x[1], final_classtable_y[1],
-                   final_classtable_x[2], final_classtable_y[2],
-                   lwd = classtable_lwd
-              )
-
-              segments(mean(final_classtable_x), final_classtable_y[1], mean(final_classtable_x), final_classtable_y[2], col = gray(0), lwd = classtable_lwd)
-              segments(final_classtable_x[1], mean(final_classtable_y), final_classtable_x[2], mean(final_classtable_y), col = gray(0), lwd = classtable_lwd)
-
-
-              # Column titles: ----
-
-              text(
-                x = mean(mean(final_classtable_x)),
-                y = header_y,
-                "Truth", pos = 1, cex = header_cex
-              )
-
-              text(
-                x = final_classtable_x[1] + .25 * diff(final_classtable_x),
-                y = subheader_y, pos = 1, cex = subheader_cex,
-                truth.labels[2]
-              )
-
-              text(
-                x = final_classtable_x[1] + .75 * diff(final_classtable_x),
-                y = subheader_y, pos = 1, cex = subheader_cex,
-                truth.labels[1]
-              )
-
-
-              # Row titles: ----
-
-              text(
-                x = final_classtable_x[1] - .01,
-                y = final_classtable_y[1] + .75 * diff(final_classtable_y), cex = subheader_cex,
-                decision.labels[2], adj = 1
-              )
-
-              text(
-                x = final_classtable_x[1] - .01,
-                y = final_classtable_y[1] + .25 * diff(final_classtable_y), cex = subheader_cex,
-                decision.labels[1], adj = 1
-              )
-
-              text(
-                x = final_classtable_x[1] - .065,
-                y = mean(final_classtable_y), cex = header_cex,
-                "Decision"
-              )
-
-              # text(x = final_classtable_x[1] - .05,
-              #      y = mean(final_classtable_y), cex = header_cex,
-              #      "Decision", srt = 90, pos = 3)
-
-
-              # Add final frequencies: ----
-
-              text(final_classtable_x[1] + .75 * diff(final_classtable_x),
-                   final_classtable_y[1] + .25 * diff(final_classtable_y),
-                   prettyNum(final_stats$cr, big.mark = ","),
-                   cex = 1.5
-              )
-
-              text(final_classtable_x[1] + .25 * diff(final_classtable_x),
-                   final_classtable_y[1] + .25 * diff(final_classtable_y),
-                   prettyNum(final_stats$mi, big.mark = ","),
-                   cex = 1.5
-              )
+    if (n_levels == 3) {
+      ball_box_width <- 14
+    }
 
-              text(final_classtable_x[1] + .75 * diff(final_classtable_x),
-                   final_classtable_y[1] + .75 * diff(final_classtable_y),
-                   prettyNum(final_stats$fa, big.mark = ","),
-                   cex = 1.5
-              )
+    if (n_levels == 4) {
+      ball_box_width <- 18
+    }
 
-              text(final_classtable_x[1] + .25 * diff(final_classtable_x),
-                   final_classtable_y[1] + .75 * diff(final_classtable_y),
-                   prettyNum(final_stats$hi, big.mark = ","),
-                   cex = 1.5
-              )
+    ball_box_height <- 2.5
+    ball_box_horiz_shift <- 10
+    ball_box_vert_shift <- -1
+    ball_box_max_shift_p <- .9
+    ball_box_min_shift_p <- .4
 
+    ball_box_fixed_x_shift <- c(ball_box_min_shift_p * plot_width, ball_box_max_shift_p * plot_width)
 
-              # Add symbols: ----
+    noise_ball_pch <- ball_pch[1]
+    signal_ball_pch <- ball_pch[2]
+    noise_ball_col <- ball_col[1]
+    signal_ball_col <- ball_col[2]
+    noise_ball_bg <- ball_bg[1]
+    signal_ball_bg <- ball_bg[2]
 
-              points(final_classtable_x[1] + .55 * diff(final_classtable_x),
-                     final_classtable_y[1] + .05 * diff(final_classtable_y),
-                     pch = noise_ball_pch, bg = col_correct_bg, col = col_correct_border, cex = ball_cex
-              )
+    arrow_lty <- 1
+    arrow_lwd <- 1
+    arrow_length <- 2.50
+    arrow_head_length <- .08
+    arrow_col <- gray(0) # = black
 
-              points(final_classtable_x[1] + .05 * diff(final_classtable_x),
-                     final_classtable_y[1] + .55 * diff(final_classtable_y),
-                     pch = signal_ball_pch, bg = col_correct_bg, cex = ball_cex, col = col_correct_border
-              )
+    if (is.null(label.performance)) { # user argument not set:
 
-              points(final_classtable_x[1] + .55 * diff(final_classtable_x),
-                     final_classtable_y[1] + .55 * diff(final_classtable_y),
-                     pch = noise_ball_pch, bg = col_error_bg, col = col_error_border, cex = ball_cex
-              )
+      if (data == "train") {
+        label.performance <- "Accuracy (Training)"
+      }
+      if (data == "test") {
+        label.performance <- "Accuracy (Testing)"
+      }
+    }
 
-              points(final_classtable_x[1] + .05 * diff(final_classtable_x),
-                     final_classtable_y[1] + .05 * diff(final_classtable_y),
-                     pch = signal_ball_pch, bg = col_error_bg, col = col_error_border, cex = ball_cex
-              )
+    # Top ----------------------------------------------------------------------
 
+    if (show.top) {
+      par(mar = c(0, 0, 1, 0))
 
-              # Add labels: ----
+      # Prepare plot:
+      plot(1,
+        xlim = c(0, 1), ylim = c(0, 1), bty = "n", type = "n",
+        xlab = "", ylab = "", yaxt = "n", xaxt = "n"
+      )
 
-              text(final_classtable_x[1] + .62 * diff(final_classtable_x),
-                   final_classtable_y[1] + .07 * diff(final_classtable_y),
-                   "cr",
-                   cex = 1, font = 3, adj = 0
-              )
+      par(xpd = TRUE)
 
-              text(final_classtable_x[1] + .12 * diff(final_classtable_x),
-                   final_classtable_y[1] + .07 * diff(final_classtable_y),
-                   "mi",
-                   cex = 1, font = 3, adj = 0
-              )
+      plot_title(
+        main = main,
+        hlines = hlines,
+        col_panel_line = col_panel_line,
+        panel_line_lwd = panel_line_lwd,
+        panel_line_lty = panel_line_lty,
+        panel_title_cex = panel_title_cex
+      )
 
-              text(final_classtable_x[1] + .62 * diff(final_classtable_x),
-                   final_classtable_y[1] + .57 * diff(final_classtable_y),
-                   "fa",
-                   cex = 1, font = 3, adj = 0
-              )
+      plot_level_bar(
+        title = paste("p(", truth.labels[1], ")", sep = ""),
+        value = 1 - crit_br,
+        value_label = scales::percent(1 - crit_br),
+        max_value = 1,
+        rect_min_y = .1,
+        rect_max_y = .6,
+        rect_min_x = .175,
+        rect_max_x = .225,
+        label_pos = "left"
+      )
 
-              text(final_classtable_x[1] + .12 * diff(final_classtable_x),
-                   final_classtable_y[1] + .57 * diff(final_classtable_y),
-                   "hi",
-                   cex = 1, font = 3, adj = 0
-              )
+      plot_icon_array(
+        x_lim = c(.33, .67),
+        y_lim = c(.12, .52),
+        n_vec = c(with(final_stats, fa + cr), with(final_stats, hi + mi)),
+        pch_vec = c(noise_ball_pch, signal_ball_pch),
+        bg_vec = c(noise_ball_bg, signal_ball_bg),
+        col_vec = c(noise_ball_col, signal_ball_col),
+        ball_cex = ball_cex,
+        n_per_icon = n_per_icon,
+        truth.labels = truth.labels,
+        show_truth_labels = TRUE,
+        show_exemplar_total = TRUE
+      )
 
-            } # if (show.confusion).
+      par(xpd = FALSE)
+
+      plot_level_bar(
+        title = paste("p(", truth.labels[2], ")", sep = ""),
+        value = crit_br,
+        value_label = scales::percent(crit_br),
+        max_value = 1,
+        rect_min_y = .1,
+        rect_max_y = .6,
+        rect_min_x = .775,
+        rect_max_x = .825,
+        label_pos = "right"
+      )
+    }
 
+    # Middle ----------------------------------------------------------------------
 
-            # Levels: ----
+    if (show.middle) {
+      if ((show.top == FALSE) & (show.bottom == FALSE)) {
+        par(mar = c(3, 3, 3, 3) + .1)
+      } else {
+        par(mar = c(0, 0, 0, 0))
+      }
 
-            if (show.levels) {
+      par(xpd = TRUE)
 
-              if (level.type %in% c("line", "bar")) {
+      # Prepare plot:
+      plot(1,
+        xlim = c(-plot_width, plot_width),
+        ylim = c(-plot_height, 0),
+        type = "n", bty = "n",
+        xaxt = "n", yaxt = "n",
+        ylab = "", xlab = ""
+      )
 
-                # Color function (taken from colorRamp2 function in circlize package)
-                # col.fun <- circlize::colorRamp2(c(0, .75, 1),
-                #                                 c("red", "yellow", "green"),
-                #                                 transparency = .5)
+      if (show.top | show.bottom) {
+        if (is.null(label.tree)) {
+          label.tree <- paste("FFT #", tree, " (of ", x$trees$n, ")", sep = "")
+        }
 
-                paste(final_stats$cr, "/", 1, collapse = "")
+        plot_title(
+          main = label.tree,
+          hlines = hlines,
+          y = 0,
+          y_dev = 20,
+          x_dev = 8,
+          x_start = -plot_width,
+          x_end = plot_width,
+          col_panel_line = col_panel_line,
+          panel_line_lwd = panel_line_lwd,
+          panel_line_lty = panel_line_lty,
+          panel_title_cex = panel_title_cex
+        )
+      }
 
-                # Add 100% reference line: ----
+      if (show.top == FALSE & show.bottom == FALSE) {
+        if (is.null(main) & is.null(x$params$main)) {
+          main <- ""
+        }
 
-                # segments(x0 = lloc$center_x[lloc$element == "mcu"] - lloc$width[lloc$element == "mcu"] * .8,
-                #          y0 = level_top,
-                #          x1 = lloc$center_x[lloc$element == "bacc"] + lloc$width[lloc$element == "bacc"] * .8,
-                #          y1 = level_top,
-                #          lty = 3, lwd = .75)
+        mtext(text = main, side = 3, cex = panel_title_cex, ...) # title 2 (middle): (b) main label
+      }
 
+      plot_icon_guide(
+        what = what,
+        data = data,
+        plot_width = plot_width,
+        plot_height = plot_height,
+        decision.labels = decision.labels,
+        noise_ball_pch = noise_ball_pch,
+        signal_ball_pch = signal_ball_pch,
+        col_correct_border = col_correct_border,
+        col_error_border = col_error_border,
+        col_correct_bg = col_correct_bg,
+        col_error_bg = col_error_bg,
+        ball_cex = ball_cex
+      )
 
-                # mcu level: ----
+      par(xpd = FALSE)
+
+      plot_fft(
+        level_stats = level_stats,
+        cue.cex = cue.cex,
+        threshold.cex = threshold.cex,
+        decision.cex = decision.cex,
+        decision.labels = decision.labels,
+        ball_loc = ball_loc,
+        show.icons = show.icons,
+        n_per_icon = n_per_icon,
+        grayscale = grayscale,
+        add = TRUE
+      )
+    }
 
-                add_level("mcu", ok_val = .75, min_val = 0, max_val = 1,
-                          level_type = level.type, lloc_row = lloc[lloc$element == "mcu", ],
-                          header_y = header_y, header_cex = header_cex) # , sub = paste(c(final_stats$cr, "/", final_stats$cr + final_stats$fa), collapse = ""))
+    # Bottom ----------------------------------------------------------------------
 
+    if (show.bottom) { # obtain tree statistics:
 
-                # pci level: ----
+      par(mar = c(0, 0, 2, 0))
 
-                add_level("pci", ok_val = .75, min_val = 0, max_val = 1,
-                          level_type = level.type, lloc_row = lloc[lloc$element == "pci", ],
-                          header_y = header_y, header_cex = header_cex) # , sub = paste(c(final_stats$cr, "/", final_stats$cr + final_stats$fa), collapse = ""))
+      plot(1,
+        xlim = c(0, 1), ylim = c(0, 1),
+        bty = "n", type = "n",
+        xlab = "", ylab = "",
+        yaxt = "n", xaxt = "n"
+      )
 
-                # text(lloc$center_x[lloc$element == "pci"],
-                #      lloc$center_y[lloc$element == "pci"],
-                #      labels = paste0("mcu\n", round(mcu, 2)))
+      if (what != "roc") {
+        # Set par:
+        par(xpd = TRUE)
+
+        plot_title(
+          main = label.performance,
+          hlines = hlines,
+          x_dev = .2,
+          y = 1.1,
+          col_panel_line = col_panel_line,
+          panel_line_lwd = panel_line_lwd,
+          panel_line_lty = panel_line_lty,
+          panel_title_cex = panel_title_cex
+        )
+
+        par(xpd = FALSE)
+      } # if (what != "roc").
+
+      # Level parameters:
+      level_height_max <- .65
+      level_width <- .05
+      level_center_y <- .45
+      # level_bottom <- .1
+      level_bottom <- level_center_y - (level_height_max / 2)
+      level_top <- level_center_y + (level_height_max / 2)
+
+      # Get either bacc OR wacc (based on sens.w):
+      sens.w <- x$params$sens.w
+      bacc_wacc <- get_bacc_wacc(sens = final_stats$sens, spec = final_stats$spec, sens.w = sens.w)
+      bacc_wacc_name <- names(bacc_wacc)
+
+      # Set labels, values, and locations (as df):
+      lloc <- data.frame(
+        element = c("classtable", "mcu", "pci", "sens", "spec", "acc", bacc_wacc_name, "roc"),
+        long_name = c("Classification Table", "mcu", "pci", "sens", "spec", "acc", bacc_wacc_name, "ROC"), # used by add_level() helper function
+        center_x = c(.18, seq(.35, .65, length.out = 6), .85),
+        center_y = rep(level_center_y, 8),
+        width = c(.20, rep(level_width, 6), .20),
+        height = c(.65, rep(level_height_max, 6), .65),
+        value = c(
+          NA,
+          abs(final_stats$mcu - 5) / (abs(1 - 5)), final_stats$pci,
+          final_stats$sens, final_stats$spec,
+          with(final_stats, (cr + hi) / n), bacc_wacc, NA
+        ),
+        value_name = c(
+          NA,
+          round(final_stats$mcu, 1), pretty_dec(final_stats$pci), # used by add_level() helper function
+          pretty_dec(final_stats$sens), pretty_dec(final_stats$spec),
+          pretty_dec(final_stats$acc), pretty_dec(bacc_wacc), NA
+        )
+      )
 
+      lloc$reference_val[lloc$element == "acc"] <- max(crit_br, 1 - crit_br)
+      lloc$reference_label[lloc$element == "acc"] <- "BL"
 
-                # spec level: ----
+      plot_confusion(
+        lloc = lloc,
+        truth.labels = truth.labels,
+        decision.labels = decision.labels,
+        final_stats = final_stats,
+        ball_cex = ball_cex
+      )
 
-                add_level("spec", ok_val = .75, min_val = 0, max_val = 1,
-                          level_type = level.type, lloc_row = lloc[lloc$element == "spec", ],
-                          header_y = header_y, header_cex = header_cex) # , sub = paste(c(final_stats$cr, "/", final_stats$cr + final_stats$fa), collapse = ""))
+      if (show.levels) {
+        for (element_i in c("mcu", "pci", "sens", "spec", "acc", "bacc")) {
+          plot_level_bar(
+            title = element_i,
+            value = lloc$value[lloc$element == element_i],
+            value_label = lloc$value_name[lloc$element == element_i],
+            max_value = 1,
+            y_title = .88,
+            cex_label = 1.5,
+            rect_min_y = .12,
+            rect_max_y = .78,
+            fill = "white",
+            y_reference = lloc$reference_val[lloc$element == element_i],
+            y_reference_label = lloc$reference_label[lloc$element == element_i],
+            rect_min_x = lloc$center_x[lloc$element == element_i] - lloc$width[lloc$element == element_i] / 2,
+            rect_max_x = lloc$center_x[lloc$element == element_i] + lloc$width[lloc$element == element_i] / 2,
+            label_pos = "top",
+            outline = FALSE
+          )
+        }
+      }
 
+      if (show.roc) {
+        plot_roc(lloc = lloc, tree_stats = tree_stats, tree = tree)
+      }
+    }
+  }
 
-                # sens level: ----
+  return(invisible(x))
+}
+
+# Helpers
+
+plot_level_bar <- function(title = "",
+                           value = NULL,
+                           value_label = value,
+                           max_value = 1,
+                           y_reference = NA,
+                           y_reference_label = NULL,
+                           cex_reference_label = 1,
+                           rect_max_y = 1,
+                           rect_min_y = 0,
+                           rect_min_x = 0,
+                           rect_max_x = 1,
+                           cex_title = 1.2,
+                           cex_label = 1.2,
+                           y_title = rect_max_y,
+                           col_outline = "black",
+                           fill = "gray",
+                           label_pos = "top",
+                           reference_val = NULL,
+                           reference_label = NULL,
+                           outline = TRUE) {
+  rect_x_center <- (rect_max_x + rect_min_x) / 2
+  rect_y_center <- (rect_max_y + rect_min_y) / 2
+
+  y_scaled <- rect_min_y + value / max_value * (rect_max_y - rect_min_y)
+
+  ## Title ================================================================
+
+  text(
+    x = rect_x_center,
+    y = y_title,
+    labels = title,
+    pos = 3,
+    cex = cex_title
+  )
+
+  ## Filling ==============================================================
+
+  rect(
+    xleft = rect_min_x,
+    xright = rect_max_x,
+    ybottom = rect_min_y,
+    ytop = y_scaled,
+    col = fill,
+    border = "black"
+  )
+
+  ## Top of filling =======================================================
+
+  segments(
+    x0 = rect_min_x,
+    x1 = rect_max_x,
+    y0 = y_scaled,
+    y1 = y_scaled,
+    lwd = 1
+  )
+
+  ## Outline ==============================================================
+
+  if (outline) {
+    rect(
+      xleft = rect_min_x,
+      xright = rect_max_x,
+      ybottom = rect_min_y,
+      ytop = rect_max_y,
+      lwd = 1,
+      border = col_outline,
+      col = NULL
+    )
+  }
 
-                add_level("sens", ok_val = .75, min_val = 0, max_val = 1,
-                          level_type = level.type, lloc_row = lloc[lloc$element == "sens", ],
-                          header_y = header_y, header_cex = header_cex) # , sub = paste(c(final_stats$hi, "/", final_stats$hi + final_stats$mi), collapse = ""))
+  ## Reference Line =======================================================
+
+  if (!is.na(y_reference)) {
+    y_reference_scaled <- rect_min_y + y_reference / max_value * (rect_max_y - rect_min_y)
+
+    segments(
+      x0 = rect_min_x,
+      x1 = rect_max_x,
+      y0 = y_reference_scaled,
+      y1 = y_reference_scaled,
+      lwd = 1,
+      lty = 3
+    )
+
+    if (!is.null(y_reference_label)) {
+      text(
+        x = rect_x_center,
+        y = y_reference_scaled,
+        labels = y_reference_label,
+        pos = 1,
+        cex = cex_reference_label
+      )
+    }
+  }
 
+  ## Value Text ===========================================================
+
+  if (label_pos == "top") {
+    x_text <- rect_x_center
+    y_text <- y_scaled
+    pos_label <- 3
+  } else if (label_pos == "left") {
+    x_text <- rect_min_x
+    y_text <- y_scaled
+    pos_label <- 2
+  } else if (label_pos == "right") {
+    x_text <- rect_max_x
+    y_text <- y_scaled
+    pos_label <- 4
+  }
 
-                # acc level: ----
+  text(
+    x = x_text,
+    y = y_text,
+    labels = value_label,
+    pos = pos_label,
+    cex = cex_label
+  )
+}
+
+plot_icon_array <- function(x_lim = c(-10, 0),
+                            y_lim = c(-2, 0),
+                            n_vec = c(20, 10),
+                            pch_vec = c(21, 21),
+                            ball_cex = 1,
+                            bg_vec = "white",
+                            col_vec = "black",
+                            ball_lwd = .70,
+                            freq_text = TRUE,
+                            freq_text_cex = 1.2,
+                            box_col = NULL,
+                            box_bg = NULL,
+                            n_per_icon = NULL,
+                            show_legend = FALSE,
+                            truth.labels = c("FALSE", "TRUE"),
+                            show_truth_labels = TRUE,
+                            show_exemplar_total = TRUE) {
+  par(xpd = TRUE)
+
+  if (show_exemplar_total) {
+    text(
+      x = .50, y = .78,
+      paste("N = ", prettyNum(sum(n_vec), big.mark = ","), "", sep = ""),
+      cex = 1.25
+    ) # N
+  }
 
-                min_acc <- max(crit_br, 1 - crit_br)  # accuracy baseline
+  if (show_truth_labels) {
+    text(.50, .63, paste(truth.labels[1], sep = ""), pos = 2, cex = 1.2, adj = 1) # 1: False
+    text(.50, .63, paste(truth.labels[2], sep = ""), pos = 4, cex = 1.2, adj = 0) # 2: True
+  }
 
-                add_level("acc", ok_val = .50, min_val = 0, max_val = 1,
-                          level_type = level.type, lloc_row = lloc[lloc$element == "acc", ],
-                          header_y = header_y, header_cex = header_cex) # , sub = paste(c(final_stats$hi + final_stats$cr, "/", final_stats$n), collapse = ""))
+  # Add box:
+  if (is.null(box_col) == FALSE | is.null(box_bg) == FALSE) {
+    rect(x_lim[1],
+      y_lim[1],
+      x_lim[2],
+      y_lim[2],
+      col = box_bg,
+      border = box_col
+    )
+  }
 
-                # Add baseline to acc level:
-                segments(
-                  x0 = (lloc$center_x[lloc$element == "acc"] - lloc$width[lloc$element  == "acc"] / 2),
-                  y0 = (lloc$center_y[lloc$element == "acc"] - lloc$height[lloc$element == "acc"] / 2) + (lloc$height[lloc$element == "acc"] * min_acc),
-                  x1 = (lloc$center_x[lloc$element == "acc"] + lloc$width[lloc$element  == "acc"] / 2),
-                  y1 = (lloc$center_y[lloc$element == "acc"] - lloc$height[lloc$element == "acc"] / 2) + (lloc$height[lloc$element == "acc"] * min_acc),
-                  lty = 3
-                )
+  a_n <- n_vec[1]
+  b_n <- n_vec[2]
 
-                text(
-                  x = lloc$center_x[lloc$element == "acc"],
-                  y = (lloc$center_y[lloc$element == "acc"] - lloc$height[lloc$element == "acc"] / 2) + lloc$height[lloc$element == "acc"] * min_acc,
-                  labels = "BL", pos = 1
-                )
+  # a_p <- n_vec[1] / sum(n_vec)  # is NOT used anywhere?
 
-                # paste("BL = ", pretty_dec(min_acc), sep = ""), pos = 1)
+  box_x_center <- sum(x_lim) / 2
+  # box_y_center <- sum(y_lim) / 2      # is NOT used anywhere?
+  # box_x_width <- x_lim[2] - x_lim[1]  # is NOT used anywhere?
 
+  if (is.null(n_per_icon)) { # determine cases per ball/icon:
 
-                # bacc OR wacc level: ----
+    n_per_icon <- calculate_n_per_icon(max(c(a_n, b_n)))
+  }
 
-                if (names(bacc_wacc) == "bacc"){ # show bacc level:
+  # Determine general ball/icon locations:
 
-                  add_level("bacc", ok_val = .50, min_val = 0, max_val = 1,
-                            level_type = level.type, lloc_row = lloc[lloc$element == "bacc", ],
-                            header_y = header_y, header_cex = header_cex)
+  a_balls <- ceiling(a_n / n_per_icon)
+  b_balls <- ceiling(b_n / n_per_icon)
+  # n_balls <- a_balls + b_balls  # is NOT used anywhere?
 
-                } else { # show wacc level (and sens.w value):
+  a_ball_x <- 0
+  a_ball_y <- 0
+  b_ball_x <- 0
+  b_ball_y <- 0
 
-                  sens.w_lbl <- paste0("sens.w = .", pretty_dec(sens.w))
+  if (a_balls > 0) {
+    a_ball_x <- rep(-1:-10, each = 5, length.out = 50)[1:a_balls]
+    a_ball_y <- rep(1:5, times = 10, length.out = 50)[1:a_balls]
+    a_ball_x <- a_ball_x * (x_lim[2] - box_x_center) / 10 + box_x_center
+    a_ball_y <- a_ball_y * (y_lim[2] - y_lim[1]) / 5 + y_lim[1]
+  }
 
-                  add_level("wacc", ok_val = .50, min_val = 0, max_val = 1,
-                            level_type = level.type, lloc_row = lloc[lloc$element == "wacc", ],
-                            header_y = header_y,
-                            bottom_text = sens.w_lbl,  # (only here)
-                            header_cex = header_cex)
+  if (b_balls > 0) {
+    b_ball_x <- rep(1:10, each = 5, length.out = 50)[1:b_balls]
+    b_ball_y <- rep(1:5, times = 10, length.out = 50)[1:b_balls]
+    b_ball_x <- b_ball_x * (x_lim[2] - box_x_center) / 10 + box_x_center
+    b_ball_y <- b_ball_y * (y_lim[2] - y_lim[1]) / 5 + y_lim[1]
+  }
 
-                } # if (bacc_wacc).
+  # Add frequency text: ----
 
+  if (freq_text) {
+    text(box_x_center, y_lim[1] - 1 * (y_lim[2] - y_lim[1]) / 5, prettyNum(b_n, big.mark = ","), pos = 4, cex = freq_text_cex)
+    text(box_x_center, y_lim[1] - 1 * (y_lim[2] - y_lim[1]) / 5, prettyNum(a_n, big.mark = ","), pos = 2, cex = freq_text_cex)
+  }
 
-                # Add baseline (at bottom?):
-                #
-                # segments(x0 = mean(lloc$center_x[2]),
-                #          y0 = lloc$center_y[1] - lloc$height[1] / 2,
-                #          x1 = mean(lloc$center_x[7]),
-                #          y1 = lloc$center_y[1] - lloc$height[1] / 2, lend = 1,
-                #          lwd = .5,
-                #          col = gray(0))
+  # Draw balls: ----
+
+  # Noise:
+  suppressWarnings(if (a_balls > 0) {
+    points(
+      x = a_ball_x,
+      y = a_ball_y,
+      pch = pch_vec[1],
+      bg = bg_vec[1],
+      col = col_vec[1],
+      cex = ball_cex,
+      lwd = ball_lwd
+    )
+  })
+
+  # Signal:
+  suppressWarnings(if (b_balls > 0) {
+    points(
+      x = b_ball_x,
+      y = b_ball_y,
+      pch = pch_vec[2],
+      bg = bg_vec[2],
+      col = col_vec[2],
+      cex = ball_cex,
+      lwd = ball_lwd
+    )
+  })
+
+  if (show_legend) {
+    text(.98, 0, labels = paste("Showing ", n_per_icon, " cases per icon:", sep = ""), pos = 2)
+    points(.98, 0, pch = noise_ball_pch, cex = ball_cex)
+    points(.99, 0, pch = signal_ball_pch, cex = ball_cex)
+  }
 
+  par(xpd = FALSE)
+}
+
+plot_fft <- function(level_stats = NULL,
+                     cue.cex = 1.5,
+                     threshold.cex = 1,
+                     decision.cex = 1,
+                     decision.labels = c("FALSE", "TRUE"),
+                     ball_loc = "variable",
+                     show.icons = TRUE,
+                     plot_width = NULL,
+                     plot_height = NULL,
+                     n_per_icon = NULL,
+                     grayscale = FALSE,
+                     add = FALSE) {
+  subplot_center <- c(0, -4)
+  label_box_height <- 2
+  label_box_width <- 5
+  f_cex <- 1
+  segment_lty <- 1
+  segment_lwd <- 1
+  arrow_lty <- 1
+  arrow_lwd <- 1
+  arrow_length <- 2.50
+  arrow_head_length <- .08
+  arrow_col <- gray(0) # = black
+  decision_node_pch <- NA_integer_
+  decision_node_cex <- 4 * f_cex
+  exit_node_cex <- 4 * f_cex
+  ball_box_height <- 2.5
+  ball_box_horiz_shift <- 10
+  ball_box_vert_shift <- -1
+  ball_box_max_shift_p <- .9
+  ball_box_min_shift_p <- .4
+  ball_box_width <- 10
+  col_exit_node_bg <- "white"
+
+  ball_col <- c(gray(0), gray(0)) # = black
+  ball_bg <- c(gray(1), gray(1)) # = white
+  ball_pch <- c(21, 24)
+  ball_cex <- c(1, 1)
+
+  noise_ball_pch <- ball_pch[1]
+  signal_ball_pch <- ball_pch[2]
+  noise_ball_col <- ball_col[1]
+  signal_ball_col <- ball_col[2]
+  noise_ball_bg <- ball_bg[1]
+  signal_ball_bg <- ball_bg[2]
+  exit_node_pch <- 21
+
+  if (!grayscale) {
+    col_error_bg <- "#FF7352CC"
+    col_error_border <- "#AD1A0AE6"
+    col_correct_bg <- "#89FF6FCC"
+    col_correct_border <- "#24AB18E6"
+  } else {
+    # Grayscale colors
+
+    col_error_bg <- gray(.1)
+    col_error_border <- gray(0)
+    col_correct_bg <- gray(1)
+    col_correct_border <- gray(0)
+  }
 
-              } # if (level.type %in% c("line", "bar")).
+  plotting_parameters_df <- data.frame(
+    n_levels = 1:6,
+    plot_height = c(10, 12, 15, 19, 23, 25),
+    plot_width = c(14, 16, 20, 24, 28, 32) * 1, # stretch to default width
+    label_box_text_cex = cue.cex,
+    break_label_cex = threshold.cex
+  )
 
-            } # if (show.levels).
+  n_levels <- nrow(level_stats)
 
+  # local variables:
+  if (n_levels < 6) {
+    label_box_text_cex <- plotting_parameters_df$label_box_text_cex[n_levels]
+    break_label_cex <- plotting_parameters_df$break_label_cex[n_levels]
 
-            # ROC curve: -----
+    if (is.null(plot_height)) {
+      plot_height <- plotting_parameters_df$plot_height[n_levels]
+    }
 
-            if (show.roc) {
+    if (is.null(plot_width)) {
+      plot_width <- plotting_parameters_df$plot_width[n_levels]
+    }
+  } else { # n_levels >= 6:
 
-              # Parameters:
-              roc_border_lwd <- 1
-              roc_border_col <- gray(0)
+    label_box_text_cex <- plotting_parameters_df$label_box_text_cex[6]
+    break_label_cex <- plotting_parameters_df$break_label_cex[6]
 
-              roc_title <- "ROC"
-              roc_title_font <- 1
+    if (is.null(plot_height)) {
+      plot_height <- plotting_parameters_df$plot_height[6]
+    }
 
-              roc_curve_col <- gray(.01) # ~black
-              roc_curve_lwd <- 1.1
+    if (is.null(plot_width)) {
+      plot_width <- plotting_parameters_df$plot_width[6]
+    }
+  }
 
-              diag_col <- gray(.01) # ~black
-              diag_lty <- 3
+  cue.labels <- level_stats$cue
 
-              x_lbl <- expression(1 - Specificity~(FAR)) # to plot minus, rather than dash
-              y_lbl <- expression(Sensitivity~(HR))
+  if (is.null(n_per_icon)) {
+    n_per_icon <- calculate_n_per_icon(max(c(level_stats$hi, level_stats$fa, level_stats$mi, level_stats$cr)))
+  }
 
-              x_d <- .015  # distance of x-axis labels (on left) to x-axis
+  if (!add) {
+    plot.new()
 
-              # y-locations of legend labels (default: using full height):
-              roc_lbl_y <- seq(.10, .90, length.out = 5)  # SVM, RF, LR, CART, FFT
+    plot.window(
+      xlim = c(-plot_width, plot_width),
+      ylim = c(-plot_height, 0)
+    ) # Sets up the plotting
+  }
 
+  for (level_i in 1:min(c(n_levels, 6))) {
+    cur_cue <- cue.labels[level_i]
+
+    hi_i <- level_stats$hi_m[level_i]
+    fa_i <- level_stats$fa_m[level_i]
+    mi_i <- level_stats$mi_m[level_i]
+    cr_i <- level_stats$cr_m[level_i]
+
+    if (level_i == 1) {
+      rect(subplot_center[1] - label_box_width / 2,
+        subplot_center[2] + 2 - label_box_height / 2,
+        subplot_center[1] + label_box_width / 2,
+        subplot_center[2] + 2 + label_box_height / 2,
+        col = "white",
+        border = "black"
+      )
 
-              if (what == "roc"){ # ROC as main plot:
+      points(
+        x = subplot_center[1],
+        y = subplot_center[2] + 2,
+        cex = decision_node_cex,
+        pch = decision_node_pch
+      )
 
-                # Rescale key coordinates:
-                lloc$center_x[lloc$element == "roc"] <- .50
-                lloc$center_y[lloc$element == "roc"] <- .55
+      text(
+        x = subplot_center[1],
+        y = subplot_center[2] + 2,
+        labels = cur_cue,
+        cex = label_box_text_cex # WAS: get_label_cex(cur_cue, label_box_text_cex = label_box_text_cex)
+      )
+    }
 
-                lloc$width[lloc$element == "roc"]  <- .70
-                lloc$height[lloc$element == "roc"] <- .80
+    if ((level_stats$exit[level_i] %in% exit_types[c(1, 3)]) | (paste(level_stats$exit[level_i]) %in% paste(exit_types[c(1, 3)], collapse = ", "))) {
+      segments(subplot_center[1],
+        subplot_center[2] + 1,
+        subplot_center[1] - 2,
+        subplot_center[2] - 2,
+        lty = segment_lty,
+        lwd = segment_lwd
+      )
 
-                # Reset some parameters:
-                if (is.null(main) == FALSE) { roc_title <- main }
+      arrows(
+        x0 = subplot_center[1] - 2,
+        y0 = subplot_center[2] - 2,
+        x1 = subplot_center[1] - 2 - arrow_length,
+        y1 = subplot_center[2] - 2,
+        lty = arrow_lty,
+        lwd = arrow_lwd,
+        col = arrow_col,
+        length = arrow_head_length
+      )
 
-                roc_border_lwd <- .80
-                roc_border_col <- gray(.25)
+      if (decision.cex > 0) {
+        text(
+          x = subplot_center[1] - 2 - arrow_length * .7,
+          y = subplot_center[2] - 2.2,
+          labels = decision.labels[1],
+          pos = 1, font = 3, cex = decision.cex
+        )
+      }
 
-                roc_curve_col <- gray(.10) # "green2"
-                roc_curve_lwd <- 1.5
+      if (ball_loc == "fixed") {
+        ball_x_lim <- c(-max(ball_box_fixed_x_shift), -min(ball_box_fixed_x_shift))
 
-                diag_col <- gray(.60)  # as in showcues()
-                diag_lty <- 1          # as in showcues()
+        ball_y_lim <- c(
+          subplot_center[2] + ball_box_vert_shift - ball_box_height / 2,
+          subplot_center[2] + ball_box_vert_shift + ball_box_height / 2
+        )
+      }
 
-                x_d <- .035
+      if (ball_loc == "variable") {
+        ball_x_lim <- c(
+          subplot_center[1] - ball_box_horiz_shift - ball_box_width / 2,
+          subplot_center[1] - ball_box_horiz_shift + ball_box_width / 2
+        )
 
-                # y-locations of legend labels (cluster labels on top right):
-                roc_lbl_y <- seq(.55, .95, length.out = 5)  # SVM, RF, LR, CART, FFT
+        ball_y_lim <- c(
+          subplot_center[2] + ball_box_vert_shift - ball_box_height / 2,
+          subplot_center[2] + ball_box_vert_shift + ball_box_height / 2
+        )
+      }
 
-              } # if (what == "roc").
+      if ((max(c(cr_i, mi_i), na.rm = TRUE) > 0) & (show.icons == TRUE)) {
+        plot_icon_array(
+          x_lim = ball_x_lim,
+          y_lim = ball_y_lim,
+          n_vec = c(cr_i, mi_i),
+          pch_vec = c(noise_ball_pch, signal_ball_pch),
+          ball_cex = ball_cex,
+          bg_vec = c(col_correct_bg, col_error_bg),
+          col_vec = c(col_correct_border, col_error_border),
+          freq_text = TRUE,
+          n_per_icon = n_per_icon,
+          show_truth_labels = FALSE,
+          show_exemplar_total = FALSE
+        )
+      }
 
+      pos_dir_symbol <- c("<=", "<", "=", "!=", ">", ">=")[which(level_stats$direction[level_i] == c(">", ">=", "!=", "=", "<=", "<"))]
+      neg_dir_symbol <- c("<=", "<", "=", "!=", ">", ">=")[which(level_stats$direction[level_i] == c("<=", "<", "=", "!=", ">", ">="))]
 
-              # ROC plot coordinates:
-              final_roc_x <- c(lloc$center_x[lloc$element == "roc"] - lloc$width[lloc$element  == "roc"] / 2, lloc$center_x[lloc$element == "roc"] + lloc$width[lloc$element  == "roc"] / 2)
-              final_roc_y <- c(lloc$center_y[lloc$element == "roc"] - lloc$height[lloc$element == "roc"] / 2, lloc$center_y[lloc$element == "roc"] + lloc$height[lloc$element == "roc"] / 2)
+      text_outline(
+        x = subplot_center[1] - 1,
+        y = subplot_center[2],
+        labels = paste(pos_dir_symbol, " ", level_stats$threshold[level_i], sep = ""),
+        pos = 2, cex = break_label_cex, r = .1
+      )
 
+      points(
+        x = subplot_center[1] - 2,
+        y = subplot_center[2] - 2,
+        pch = exit_node_pch,
+        cex = exit_node_cex,
+        bg = col_exit_node_bg
+      )
 
-              if (what == "roc"){ # ROC as main plot:
+      text(
+        x = subplot_center[1] - 2,
+        y = subplot_center[2] - 2,
+        labels = substr(decision.labels[1], 1, 1)
+      )
+    } # if (exit node on left).
+
+    if ((level_stats$exit[level_i] %in% exit_types[c(2)]) | (paste(level_stats$exit[level_i]) %in% paste(exit_types[c(2)], collapse = ", "))) {
+      segments(subplot_center[1],
+        subplot_center[2] + 1,
+        subplot_center[1] - 2,
+        subplot_center[2] - 2,
+        lty = segment_lty,
+        lwd = segment_lwd
+      )
 
-                # Title:
-                title(main = roc_title, ...)  # + graphical parameters
+      rect(subplot_center[1] - 2 - label_box_width / 2,
+        subplot_center[2] - 2 - label_box_height / 2,
+        subplot_center[1] - 2 + label_box_width / 2,
+        subplot_center[2] - 2 + label_box_height / 2,
+        col = "white",
+        border = "black"
+      )
 
-                # Background:
-                rect(final_roc_x[1], final_roc_y[1], final_roc_x[2], final_roc_y[2],
-                     col = gray(.96))  # as in showcues()
+      if (level_i < 6) {
+        text(
+          x = subplot_center[1] - 2,
+          y = subplot_center[2] - 2,
+          labels = cue.labels[level_i + 1],
+          cex = label_box_text_cex
+        )
+      } else {
+        text(
+          x = subplot_center[1] - 2,
+          y = subplot_center[2] - 2,
+          labels = paste0("+ ", n_levels - 6, " More"),
+          cex = label_box_text_cex,
+          font = 3
+        )
+      }
+    } # if (new level on right).
+
+    if ((level_stats$exit[level_i] %in% exit_types[c(2, 3)]) | (paste(level_stats$exit[level_i]) %in% paste(exit_types[c(2, 3)], collapse = ", "))) {
+      segments(subplot_center[1],
+        subplot_center[2] + 1,
+        subplot_center[1] + 2,
+        subplot_center[2] - 2,
+        lty = segment_lty,
+        lwd = segment_lwd
+      )
 
-                # Grid:
-                x_ax_seq <- seq(final_roc_x[1], final_roc_x[2], length.out = 11)
-                y_ax_seq <- seq(final_roc_y[1], final_roc_y[2], length.out = 11)
-                abline(v = x_ax_seq, lwd = c(2, rep(1, 4)), col = gray(1)) # x-grid
-                abline(h = y_ax_seq, lwd = c(2, rep(1, 4)), col = gray(1)) # y-grid
+      arrows(
+        x0 = subplot_center[1] + 2,
+        y0 = subplot_center[2] - 2,
+        x1 = subplot_center[1] + 2 + arrow_length,
+        y1 = subplot_center[2] - 2,
+        lty = arrow_lty,
+        lwd = arrow_lwd,
+        col = arrow_col,
+        length = arrow_head_length
+      )
 
-                # Axis ticks:
-                segments(x_ax_seq, final_roc_y[1], x_ax_seq, (final_roc_y[1] - .025), lty = 1, lwd = 1, col = gray(.10)) # x-axis
-                segments(final_roc_x[1], y_ax_seq, (final_roc_x[1] - .015), y_ax_seq, lty = 1, lwd = 1, col = gray(.10)) # y-axis
+      if (decision.cex > 0) {
+        text(
+          x = subplot_center[1] + 2 + arrow_length * .7,
+          y = subplot_center[2] - 2.2,
+          labels = decision.labels[2],
+          pos = 1,
+          font = 3,
+          cex = decision.cex
+        )
+      }
 
-                # Tick labels:
-                text(x_ax_seq, (final_roc_y[1] - .025), labels = scales::comma(seq(0, 1, by = .1), accuracy = .1), pos = 1, cex = .9) # x-lbl
-                text((final_roc_x[1] - .015), y_ax_seq, labels = scales::comma(seq(0, 1, by = .1), accuracy = .1), pos = 2, cex = .9) # y-llb
+      if (ball_loc == "fixed") {
+        ball_x_lim <- c(min(ball_box_fixed_x_shift), max(ball_box_fixed_x_shift))
+        ball_y_lim <- c(
+          subplot_center[2] + ball_box_vert_shift - ball_box_height / 2,
+          subplot_center[2] + ball_box_vert_shift + ball_box_height / 2
+        )
+      }
 
-                # Axis labels:
-                text(mean(final_roc_x), final_roc_y[1] - .125, labels = x_lbl, cex = 1) # x-lab
-                text(final_roc_x[1] - (3.5 * x_d), mean(final_roc_y), labels = y_lbl, cex = 1, srt = 90) # y-lab
+      if (ball_loc == "variable") {
+        ball_x_lim <- c(
+          subplot_center[1] + ball_box_horiz_shift - ball_box_width / 2,
+          subplot_center[1] + ball_box_horiz_shift + ball_box_width / 2
+        )
 
-                # Subtitle: Note data used
-                subnote <- paste0("ROC for '", data, "' data:")
-                text(x = (final_roc_x[1] - .015), y = (final_roc_y[2] + .03),
-                     labels = subnote, pos = 4, cex = subheader_cex)
+        ball_y_lim <- c(
+          subplot_center[2] + ball_box_vert_shift - ball_box_height / 2,
+          subplot_center[2] + ball_box_vert_shift + ball_box_height / 2
+        )
+      }
 
+      if ((max(c(fa_i, hi_i), na.rm = TRUE) > 0) & (show.icons == TRUE)) {
+        plot_icon_array(
+          x_lim = ball_x_lim,
+          y_lim = ball_y_lim,
+          n_vec = c(fa_i, hi_i),
+          pch_vec = c(noise_ball_pch, signal_ball_pch),
+          ball_cex = ball_cex,
+          # bg_vec = c(noise_ball_bg, signal_ball_bg),
+          bg_vec = c(col_error_bg, col_correct_bg),
+          col_vec = c(col_error_border, col_correct_border),
+          freq_text = TRUE,
+          n_per_icon = n_per_icon,
+          show_truth_labels = FALSE, show_exemplar_total = FALSE
+        )
+      }
 
-              } else { # ROC as miniature plot:
+      dir_symbol <- c("<=", "<", "=", "!=", ">", ">=") # as (local) constant
 
-                # Title:
-                text(lloc$center_x[lloc$element == "roc"], header_y, labels = roc_title,
-                     font = roc_title_font, pos = 1, cex = header_cex)
+      pos_dir_symbol <- dir_symbol[which(level_stats$direction[level_i] == c("<=", "<", "=", "!=", ">", ">="))]
+      neg_dir_symbol <- dir_symbol[which(level_stats$direction[level_i] == rev(c("<=", "<", "=", "!=", ">", ">=")))]
 
-                # x-axis:
-                text(c(final_roc_x[1], final_roc_x[2]),
-                     c(final_roc_y[1], final_roc_y[1]) - .04,
-                     labels = c(0, 1)
-                )
+      text_outline(subplot_center[1] + 1,
+        subplot_center[2],
+        labels = paste(pos_dir_symbol, " ", level_stats$threshold[level_i], sep = ""),
+        pos = 4, cex = break_label_cex, r = .1
+      )
 
-                text(mean(final_roc_x), final_roc_y[1] - .08, labels = x_lbl) # x-lab
+      points(
+        x = subplot_center[1] + 2,
+        y = subplot_center[2] - 2,
+        pch = exit_node_pch,
+        cex = exit_node_cex,
+        bg = col_exit_node_bg
+      )
 
-                # y-axis:
-                text(c(final_roc_x[1], final_roc_x[1], final_roc_x[1]) - x_d,
-                     c(final_roc_y[1], mean(final_roc_y[1:2]), final_roc_y[2]),
-                     labels = c(0, .5, 1)
-                )
+      text(
+        x = subplot_center[1] + 2,
+        y = subplot_center[2] - 2,
+        labels = substr(decision.labels[2], 1, 1)
+      )
+    } # if (exit node on right).
+
+    if ((level_stats$exit[level_i] %in% exit_types[c(1)]) | (paste(level_stats$exit[level_i]) %in% paste(exit_types[c(1)], collapse = ", "))) {
+      segments(subplot_center[1],
+        subplot_center[2] + 1,
+        subplot_center[1] + 2,
+        subplot_center[2] - 2,
+        lty = segment_lty,
+        lwd = segment_lwd
+      )
 
-                text(final_roc_x[1] - (2.5 * x_d), mean(final_roc_y), labels = y_lbl, srt = 90) # y-lab
+      if (level_i < 6) {
+        rect(subplot_center[1] + 2 - label_box_width / 2,
+          subplot_center[2] - 2 - label_box_height / 2,
+          subplot_center[1] + 2 + label_box_width / 2,
+          subplot_center[2] - 2 + label_box_height / 2,
+          col = "white",
+          border = "black"
+        )
+
+        text(
+          x = subplot_center[1] + 2,
+          y = subplot_center[2] - 2,
+          labels = cue.labels[level_i + 1],
+          cex = label_box_text_cex
+        )
+      } else {
+        rect(subplot_center[1] + 2 - label_box_width / 2,
+          subplot_center[2] - 2 - label_box_height / 2,
+          subplot_center[1] + 2 + label_box_width / 2,
+          subplot_center[2] - 2 + label_box_height / 2,
+          col = "white",
+          border = "black", lty = 2
+        )
+
+        text(
+          x = subplot_center[1] + 2,
+          y = subplot_center[2] - 2,
+          labels = paste0("+ ", n_levels - 6, " More"),
+          cex = label_box_text_cex,
+          font = 3
+        )
+      }
+    } # if (new level on right).
 
-                # AUC label:
-                # text(final.roc.center[1], subheader_y, paste("AUC =", round(final.auc, 2)), pos = 1)
+    if (identical(paste(level_stats$exit[level_i]), paste0(exit_types[1]))) {
+      subplot_center <- c(
+        subplot_center[1] + 2,
+        subplot_center[2] - 4
+      )
+    } # if (identical exit 0 / left etc.
 
-                # Plot bg:
-                #
-                # rect(final_roc_x[1],
-                #      final_roc_y[1],
-                #      final_roc_x[2],
-                #      final_roc_y[2],
-                #      col = gray(1), lwd = .5)
+    if (identical(paste(level_stats$exit[level_i]), paste0(exit_types[2]))) {
+      subplot_center <- c(
+        subplot_center[1] - 2,
+        subplot_center[2] - 4
+      )
+    } # if (identical exit 1 / right etc.
+  } # for (level_i etc. loop.
+}
+
+plot_confusion <- function(lloc,
+                           header_y = 1,
+                           header_cex = 1.1,
+                           subheader_y = .925,
+                           subheader_cex = .9,
+                           final_stats = NULL,
+                           noise_ball_pch = 21,
+                           signal_ball_pch = 24,
+                           grayscale = FALSE,
+                           ball_cex = c(1, 1),
+                           classtable_lwd = 1,
+                           truth.labels = c("FALSE", "TRUE"),
+                           decision.labels = c("FALSE", "TRUE")) {
+  if (!grayscale) {
+    col_error_bg <- "#FF7352CC"
+    col_error_border <- "#AD1A0AE6"
+    col_correct_bg <- "#89FF6FCC"
+    col_correct_border <- "#24AB18E6"
+  } else {
+    # Grayscale colors
+
+    col_error_bg <- gray(.1)
+    col_error_border <- gray(0)
+    col_correct_bg <- gray(1)
+    col_correct_border <- gray(0)
+  }
 
-                # Gridlines:
-                # # Horizontal:
-                #  segments(x0 = rep(final_roc_x[1], 9),
-                #           y0 = seq(final_roc_y[1], final_roc_y[2], length.out = 5)[2:10],
-                #           x1 = rep(final_roc_x[2], 9),
-                #           y1 = seq(final_roc_y[1], final_roc_y[2], length.out = 5)[2:10],
-                #           lty = 1, col = gray(.8), lwd = c(.5), lend = 3
-                #           )
-                #
-                #  # Vertical:
-                #  segments(y0 = rep(final_roc_y[1], 9),
-                #           x0 = seq(final_roc_x[1], final_roc_x[2], length.out = 5)[2:10],
-                #           y1 = rep(final_roc_y[2], 9),
-                #           x1 = seq(final_roc_x[1], final_roc_x[2], length.out = 5)[2:10],
-                #           lty = 1, col = gray(.8), lwd = c(.5), lend = 3
-                #  )
+  # x/y coordinates:
+  final_classtable_x <- c(lloc$center_x[lloc$element == "classtable"] - lloc$width[lloc$element == "classtable"] / 2, lloc$center_x[lloc$element == "classtable"] + lloc$width[lloc$element == "classtable"] / 2)
+  final_classtable_y <- c(lloc$center_y[lloc$element == "classtable"] - lloc$height[lloc$element == "classtable"] / 2, lloc$center_y[lloc$element == "classtable"] + lloc$height[lloc$element == "classtable"] / 2)
+
+  rect(final_classtable_x[1], final_classtable_y[1],
+    final_classtable_x[2], final_classtable_y[2],
+    lwd = classtable_lwd
+  )
+
+  segments(mean(final_classtable_x), final_classtable_y[1], mean(final_classtable_x), final_classtable_y[2], col = gray(0), lwd = classtable_lwd)
+  segments(final_classtable_x[1], mean(final_classtable_y), final_classtable_x[2], mean(final_classtable_y), col = gray(0), lwd = classtable_lwd)
+
+  # Column titles: ----
+
+  text(
+    x = mean(mean(final_classtable_x)),
+    y = header_y,
+    "Truth", pos = 1, cex = header_cex
+  )
+
+  text(
+    x = final_classtable_x[1] + .25 * diff(final_classtable_x),
+    y = subheader_y, pos = 1, cex = subheader_cex,
+    truth.labels[2]
+  )
+
+  text(
+    x = final_classtable_x[1] + .75 * diff(final_classtable_x),
+    y = subheader_y, pos = 1, cex = subheader_cex,
+    truth.labels[1]
+  )
+
+
+  # Row titles: ----
+
+  text(
+    x = final_classtable_x[1] - .01,
+    y = final_classtable_y[1] + .75 * diff(final_classtable_y), cex = subheader_cex,
+    decision.labels[2], adj = 1
+  )
+
+  text(
+    x = final_classtable_x[1] - .01,
+    y = final_classtable_y[1] + .25 * diff(final_classtable_y), cex = subheader_cex,
+    decision.labels[1], adj = 1
+  )
+
+  text(
+    x = final_classtable_x[1] - .065,
+    y = mean(final_classtable_y), cex = header_cex,
+    "Decision"
+  )
+
+  text(final_classtable_x[1] + .75 * diff(final_classtable_x),
+    final_classtable_y[1] + .25 * diff(final_classtable_y),
+    prettyNum(final_stats$cr, big.mark = ","),
+    cex = 1.5
+  )
+
+  text(final_classtable_x[1] + .25 * diff(final_classtable_x),
+    final_classtable_y[1] + .25 * diff(final_classtable_y),
+    prettyNum(final_stats$mi, big.mark = ","),
+    cex = 1.5
+  )
+
+  text(final_classtable_x[1] + .75 * diff(final_classtable_x),
+    final_classtable_y[1] + .75 * diff(final_classtable_y),
+    prettyNum(final_stats$fa, big.mark = ","),
+    cex = 1.5
+  )
+
+  text(final_classtable_x[1] + .25 * diff(final_classtable_x),
+    final_classtable_y[1] + .75 * diff(final_classtable_y),
+    prettyNum(final_stats$hi, big.mark = ","),
+    cex = 1.5
+  )
+
+  # Add symbols: ----
+
+  points(final_classtable_x[1] + .55 * diff(final_classtable_x),
+    final_classtable_y[1] + .05 * diff(final_classtable_y),
+    pch = noise_ball_pch, bg = col_correct_bg, col = col_correct_border, cex = ball_cex
+  )
+
+  points(final_classtable_x[1] + .05 * diff(final_classtable_x),
+    final_classtable_y[1] + .55 * diff(final_classtable_y),
+    pch = signal_ball_pch, bg = col_correct_bg, cex = ball_cex, col = col_correct_border
+  )
+
+  points(final_classtable_x[1] + .55 * diff(final_classtable_x),
+    final_classtable_y[1] + .55 * diff(final_classtable_y),
+    pch = noise_ball_pch, bg = col_error_bg, col = col_error_border, cex = ball_cex
+  )
+
+  points(final_classtable_x[1] + .05 * diff(final_classtable_x),
+    final_classtable_y[1] + .05 * diff(final_classtable_y),
+    pch = signal_ball_pch, bg = col_error_bg, col = col_error_border, cex = ball_cex
+  )
+
+  # Add labels: ----
+
+  text(final_classtable_x[1] + .62 * diff(final_classtable_x),
+    final_classtable_y[1] + .07 * diff(final_classtable_y),
+    "cr",
+    cex = 1, font = 3, adj = 0
+  )
+
+  text(final_classtable_x[1] + .12 * diff(final_classtable_x),
+    final_classtable_y[1] + .07 * diff(final_classtable_y),
+    "mi",
+    cex = 1, font = 3, adj = 0
+  )
+
+  text(final_classtable_x[1] + .62 * diff(final_classtable_x),
+    final_classtable_y[1] + .57 * diff(final_classtable_y),
+    "fa",
+    cex = 1, font = 3, adj = 0
+  )
+
+  text(final_classtable_x[1] + .12 * diff(final_classtable_x),
+    final_classtable_y[1] + .57 * diff(final_classtable_y),
+    "hi",
+    cex = 1, font = 3, adj = 0
+  )
+}
+
+plot_roc <- function(lloc,
+                     title = "ROC",
+                     main = NULL,
+                     header_y = 1,
+                     border_lwd = 1,
+                     border_col = gray(0),
+                     subheader_y = .925,
+                     header_cex = 1.10,
+                     subheader_cex = .90,
+                     grayscale = FALSE,
+                     tree_stats = NULL,
+                     tree = 1) {
+  roc_title_font <- 1
+
+  roc_curve_col <- gray(.01) # ~black
+  roc_curve_lwd <- 1.1
+
+  diag_col <- gray(.01) # ~black
+  diag_lty <- 3
+
+  fft_sens_vec <- tree_stats$sens
+  fft_spec_vec <- tree_stats$spec
+
+  x_lbl <- expression(1 - Specificity ~ (FAR)) # to plot minus, rather than dash
+  y_lbl <- expression(Sensitivity ~ (HR))
+
+  x_d <- .015 # distance of x-axis labels (on left) to x-axis
+
+  # y-locations of legend labels (default: using full height):
+  roc_lbl_y <- seq(.10, .90, length.out = 5) # SVM, RF, LR, CART, FFT
+
+  # Reset some parameters:
+  if (is.null(main) == FALSE) {
+    roc_title <- main
+  }
 
-              }
+  roc_curve_col <- gray(.10) # "green2"
+  roc_curve_lwd <- 1.5
 
-              # Plot border:
-              rect(final_roc_x[1],
-                   final_roc_y[1],
-                   final_roc_x[2],
-                   final_roc_y[2],
-                   border = roc_border_col,
-                   lwd = roc_border_lwd
-              )
+  diag_col <- gray(.60) # as in showcues()
+  diag_lty <- 1 # as in showcues()
 
-              # Diagonal:
-              segments(final_roc_x[1],
-                       final_roc_y[1],
-                       final_roc_x[2],
-                       final_roc_y[2],
-                       col = diag_col,
-                       lwd = 1,
-                       lty = diag_lty
-              )
+  x_d <- .015
 
-              # FFTs: ----
-
-              {
+  # y-locations of legend labels (cluster labels on top right):
+  roc_lbl_y <- seq(.55, .95, length.out = 5) # SVM, RF, LR, CART, FFT
 
-                if (!grayscale) {
-
-                  col_fft_point_col <- scales::alpha("green", .1)
-                  col_fft_point_bg <- scales::alpha("white", .9)
-                  col_fft_point_bg_2 <- scales::alpha("green", .2)
-                  col_fft_point_col_2 <- scales::alpha("green", .6)
+  # ROC plot coordinates:
+  final_roc_x <- c(lloc$center_x[lloc$element == "roc"] - lloc$width[lloc$element == "roc"] / 2, lloc$center_x[lloc$element == "roc"] + lloc$width[lloc$element == "roc"] / 2)
+  final_roc_y <- c(lloc$center_y[lloc$element == "roc"] - lloc$height[lloc$element == "roc"] / 2, lloc$center_y[lloc$element == "roc"] + lloc$height[lloc$element == "roc"] / 2)
 
-                } else {
+  # Set par:
+  par(xpd = TRUE)
 
-                  col_fft_point_col <- gray(0)
-                  col_fft_point_bg <- gray(1)
-                  col_fft_point_bg_2 <- gray(1)
-                  col_fft_point_col_2 <- gray(0)
-                }
+  # Title:
+  text(lloc$center_x[lloc$element == "roc"], header_y,
+    labels = title,
+    font = roc_title_font, pos = 1, cex = header_cex
+  )
 
-                roc_order <- order(fft_spec_vec, decreasing = TRUE)  # from highest to lowest spec
-                # roc_order <- 1:x$trees$n
+  # x-axis:
+  text(c(final_roc_x[1], final_roc_x[2]),
+    c(final_roc_y[1], final_roc_y[1]) - .04,
+    labels = c(0, 1)
+  )
 
-                fft_sens_vec_ord <- fft_sens_vec[roc_order]
-                fft_spec_vec_ord <- fft_spec_vec[roc_order]
+  text(mean(final_roc_x), final_roc_y[1] - .08, labels = x_lbl) # x-lab
 
-                # Add segments and points for all trees but tree:
+  # y-axis:
+  text(c(final_roc_x[1], final_roc_x[1], final_roc_x[1]) - x_d,
+    c(final_roc_y[1], mean(final_roc_y[1:2]), final_roc_y[2]),
+    labels = c(0, .5, 1)
+  )
 
-                if (length(roc_order) > 1) {
+  text(final_roc_x[1] - (2.5 * x_d), mean(final_roc_y), labels = y_lbl, srt = 90) # y-lab
 
-                  segments(final_roc_x[1] + c(0, 1 - fft_spec_vec_ord) * lloc$width[lloc$element == "roc"],
-                           final_roc_y[1] + c(0, fft_sens_vec_ord) * lloc$height[lloc$element == "roc"],
-                           final_roc_x[1] + c(1 - fft_spec_vec_ord, 1) * lloc$width[lloc$element == "roc"],
-                           final_roc_y[1] + c(fft_sens_vec_ord, 1) * lloc$height[lloc$element == "roc"],
-                           lwd = roc_curve_lwd,
-                           col = roc_curve_col
-                  )
-
-                  points(final_roc_x[1] + ((1 - fft_spec_vec_ord[-(which(roc_order == tree))]) * lloc$width[lloc$element == "roc"]),
-                         final_roc_y[1] + (fft_sens_vec_ord[-(which(roc_order == tree))] * lloc$height[lloc$element == "roc"]),
-                         pch = 21, cex = 2.5, col = col_fft_point_col_2,
-                         bg = col_fft_point_bg
-                  )
+  # Plot border:
+  rect(final_roc_x[1],
+    final_roc_y[1],
+    final_roc_x[2],
+    final_roc_y[2],
+    border = border_col,
+    lwd = border_lwd
+  )
 
-                  text(final_roc_x[1] + ((1 - fft_spec_vec_ord[-(which(roc_order == tree))]) * lloc$width[lloc$element == "roc"]),
-                       final_roc_y[1] + (fft_sens_vec_ord[-(which(roc_order == tree))] * lloc$height[lloc$element == "roc"]),
-                       labels = roc_order[which(roc_order != tree)], cex = 1, col = gray(.50)
-                  )
+  # Diagonal:
+  segments(final_roc_x[1],
+    final_roc_y[1],
+    final_roc_x[2],
+    final_roc_y[2],
+    col = diag_col,
+    lwd = 1,
+    lty = diag_lty
+  )
 
-                }
-
-                # Add larger point for plotted tree:
-
-                # white point (to hide point from above):
-                points(final_roc_x[1] + ((1 - fft_spec_vec[tree]) * lloc$width[lloc$element == "roc"]),
-                       final_roc_y[1] + (fft_sens_vec[tree] * lloc$height[lloc$element == "roc"]),
-                       pch = 21, cex = 3, col = col_fft_point_col_2, # col = scales::alpha("green", .30),
-                       bg = scales::alpha("white", 1), lwd = 1
-                )
+  # FFTs: ----
 
-                # green point:
-                points(final_roc_x[1] + ((1 - fft_spec_vec[tree]) * lloc$width[lloc$element == "roc"]),
-                       final_roc_y[1] + (fft_sens_vec[tree] * lloc$height[lloc$element == "roc"]),
-                       pch = 21, cex = 3, col = col_fft_point_col_2, # col = scales::alpha("green", .30),
-                       bg = col_fft_point_bg_2, lwd = 1
-                )
+  {
+    if (!grayscale) {
+      col_fft_point_col <- scales::alpha("green", .1)
+      col_fft_point_bg <- scales::alpha("white", .9)
+      col_fft_point_bg_2 <- scales::alpha("green", .2)
+      col_fft_point_col_2 <- scales::alpha("green", .6)
+    } else {
+      col_fft_point_col <- gray(0)
+      col_fft_point_bg <- gray(1)
+      col_fft_point_bg_2 <- gray(1)
+      col_fft_point_col_2 <- gray(0)
+    }
 
-                text(final_roc_x[1] + ((1 - fft_spec_vec[tree]) * lloc$width[lloc$element == "roc"]),
-                     final_roc_y[1] + (fft_sens_vec[tree] * lloc$height[lloc$element == "roc"]),
-                     labels = tree, cex = 1.25, col = gray(.20), font = 2
-                )
+    roc_order <- order(fft_spec_vec, decreasing = TRUE) # from highest to lowest spec
+    # roc_order <- 1:x$trees$n
 
+    fft_sens_vec_ord <- fft_sens_vec[roc_order]
+    fft_spec_vec_ord <- fft_spec_vec[roc_order]
 
-              } # FFTs.
+    # Add segments and points for all trees but tree:
 
-            } # if (show.roc).
+    if (length(roc_order) > 1) {
+      segments(final_roc_x[1] + c(0, 1 - fft_spec_vec_ord) * lloc$width[lloc$element == "roc"],
+        final_roc_y[1] + c(0, fft_sens_vec_ord) * lloc$height[lloc$element == "roc"],
+        final_roc_x[1] + c(1 - fft_spec_vec_ord, 1) * lloc$width[lloc$element == "roc"],
+        final_roc_y[1] + c(fft_sens_vec_ord, 1) * lloc$height[lloc$element == "roc"],
+        lwd = roc_curve_lwd,
+        col = roc_curve_col
+      )
 
-          } # if (show.bottom).
+      points(final_roc_x[1] + ((1 - fft_spec_vec_ord[-(which(roc_order == tree))]) * lloc$width[lloc$element == "roc"]),
+        final_roc_y[1] + (fft_sens_vec_ord[-(which(roc_order == tree))] * lloc$height[lloc$element == "roc"]),
+        pch = 21, cex = 2.5, col = col_fft_point_col_2,
+        bg = col_fft_point_bg
+      )
 
-          # # Reset plotting space:
-          # par(mfrow = c(1, 1))
-          # par(mar = c(5, 4, 4, 1) + .1)
+      text(final_roc_x[1] + ((1 - fft_spec_vec_ord[-(which(roc_order == tree))]) * lloc$width[lloc$element == "roc"]),
+        final_roc_y[1] + (fft_sens_vec_ord[-(which(roc_order == tree))] * lloc$height[lloc$element == "roc"]),
+        labels = roc_order[which(roc_order != tree)], cex = 1, col = gray(.50)
+      )
+    }
 
+    # Add larger point for plotted tree:
+
+    # white point (to hide point from above):
+    points(final_roc_x[1] + ((1 - fft_spec_vec[tree]) * lloc$width[lloc$element == "roc"]),
+      final_roc_y[1] + (fft_sens_vec[tree] * lloc$height[lloc$element == "roc"]),
+      pch = 21, cex = 3, col = col_fft_point_col_2, # col = scales::alpha("green", .30),
+      bg = scales::alpha("white", 1), lwd = 1
+    )
+
+    # green point:
+    points(final_roc_x[1] + ((1 - fft_spec_vec[tree]) * lloc$width[lloc$element == "roc"]),
+      final_roc_y[1] + (fft_sens_vec[tree] * lloc$height[lloc$element == "roc"]),
+      pch = 21, cex = 3, col = col_fft_point_col_2, # col = scales::alpha("green", .30),
+      bg = col_fft_point_bg_2, lwd = 1
+    )
+
+    text(final_roc_x[1] + ((1 - fft_spec_vec[tree]) * lloc$width[lloc$element == "roc"]),
+      final_roc_y[1] + (fft_sens_vec[tree] * lloc$height[lloc$element == "roc"]),
+      labels = tree, cex = 1.25, col = gray(.20), font = 2
+    )
+  }
+}
+
+
+plot_icon_guide <- function(what = NULL,
+                            data = NULL,
+                            plot_width = NULL,
+                            plot_height = NULL,
+                            decision.labels = NULL,
+                            noise_ball_pch = NULL,
+                            signal_ball_pch = NULL,
+                            col_correct_border = NULL,
+                            col_error_border = NULL,
+                            col_correct_bg = NULL,
+                            col_error_bg = NULL,
+                            ball_cex = NULL,
+                            show_icon_guide_legend = TRUE) {
+  col_panel_line <- "black"
+
+  # Parameters:
+  if (what == "ico") {
+    f_x <- 1.2 # scaling factor (to stretch in x-dim)
+    f_y <- 0.8 # scaling factor (to shift up)
+  } else { # default scaling factors:
+
+    f_x <- 1
+    f_y <- 1
+  }
 
-  } # if (what != "cues").
+  get_exit_word <- get_exit_word(data) # either 'train':'decide' or 'test':'predict'
 
+  if (what == "ico") {
+    leg_head_y <- .02
+    leg_ball_y <- .14
+  } else {
+    leg_head_y <- .05
+    leg_ball_y <- .15
+  }
 
-  # Output: ------
+  text(-plot_width * .60 * f_x,
+    -plot_height * leg_head_y * f_y,
+    paste(get_exit_word, decision.labels[1], sep = " "),
+    cex = 1.2, font = 3
+  )
+
+  points(c(-plot_width * .70, -plot_width * .50) * f_x,
+    c(-plot_height * leg_ball_y, -plot_height * leg_ball_y) * f_y,
+    pch = c(noise_ball_pch, signal_ball_pch),
+    bg = c(col_correct_bg, col_error_bg),
+    col = c(col_correct_border, col_error_border),
+    cex = ball_cex * 1.5
+  )
+
+  text(c(-plot_width * .70, -plot_width * .50) * f_x,
+    c(-plot_height * leg_ball_y, -plot_height * leg_ball_y) * f_y,
+    labels = c("Correct\nRejection", "Miss"),
+    pos = c(2, 4), offset = .80, cex = 1
+  )
+
+  text(plot_width * .60 * f_x,
+    -plot_height * leg_head_y * f_y,
+    paste(get_exit_word, decision.labels[2], sep = " "),
+    cex = 1.2, font = 3
+  )
+
+  points(c(plot_width * .50, plot_width * .70) * f_x,
+    c(-plot_height * leg_ball_y, -plot_height * leg_ball_y) * f_y,
+    pch = c(noise_ball_pch, signal_ball_pch),
+    bg = c(col_error_bg, col_correct_bg),
+    col = c(col_error_border, col_correct_border),
+    cex = ball_cex * 1.5
+  )
+
+  text(c(plot_width * .50, plot_width * .70) * f_x,
+    c(-plot_height * leg_ball_y, -plot_height * leg_ball_y) * f_y,
+    labels = c("False\nAlarm", "Hit"),
+    pos = c(2, 4), offset = .80, cex = 1
+  )
+
+  if (what == "ico") {
+    x_hline <- plot_width * 1.0 * f_x
+    y_hline <- -plot_height * .22 * f_y
+
+    segments(-x_hline, y_hline, x_hline, y_hline, col = col_panel_line, lwd = panel_line_lwd, lty = panel_line_lty)
+    rect(-x_hline * .33, (y_hline - .5), x_hline * .33, (y_hline + .5), col = "white", border = NA)
+  }
+}
+
+plot_title <- function(hlines = TRUE,
+                       main = "TITLE",
+                       y = .95,
+                       x_start = 0,
+                       x_end = 1,
+                       y_dev = .2,
+                       x_dev = .15,
+                       col_panel_line = "black",
+                       panel_line_lwd = 1,
+                       panel_line_lty = 1,
+                       panel_title_cex = 3) {
+  # (a) lines:
+  if (hlines) {
+    segments(x_start, y, x_end, y,
+      col = col_panel_line,
+      lwd = panel_line_lwd,
+      lty = panel_line_lty
+    ) # top hline
+
+    rect((.50 - x_dev),
+      (1 - y_dev),
+      (.50 + x_dev),
+      (1 + y_dev),
+      col = "white", border = NA
+    ) # title background
+  }
 
-  # Output x may differ from input x when applying new 'test' data (as df):
-  return(invisible(x))
+  # (b) label:
+  text(x = .50, y = y, main, cex = panel_title_cex) # title 1 (top): main
+}
 
-} # plot.FFTrees().
 
+# Pluck
+pluck_level_stats <- function(fft,
+                              data_type = c("train", "test"),
+                              tree = 1) {
+  assert_fft_has_tree(fft, tree)
+  data_type <- match.arg(data_type)
 
+  out <- fft$trees$level_stats[[data_type]]
 
-# ToDo: ------
+  out <- out[out$tree == tree, ]
 
-# - Further cleanup & clutter reduction:
-#   - Remove ROC curve parts to a separate function, and
-#     handle what == "roc" as a special case (like what = "cues").
+  return(out)
+}
 
-# - Issue #91: Allow data to accept new test data (as df).
-#   Suggestion: Use a 'newdata' argument for this purpose, as in predict().)
+# Assert
+assert_fft_has_tree <- function(fft, tree) {
+  assertthat::assert_that(tree %in% fft$trees$level_stats$train$tree)
+}
 
-# - Offer options for adding/changing color information.
+calculate_n_per_icon <- function(n_max) {
+  i <- n_max / c(1, 5, 10, 50, 100, 1000, 10000, 100000)
+  i[i > 50] <- 0
 
-# eof.
+  n_per_icon <- c(1, 5, 10, 50, 100, 1000, 10000, 100000)[which(i == max(i))]
+}
diff --git a/R/util_plot.R b/R/util_plot.R
index e4722fbe..fe3d8674 100644
--- a/R/util_plot.R
+++ b/R/util_plot.R
@@ -263,157 +263,6 @@ transparent <- function(col_orig = "red",
 
 
 
-
-
-# (2) Specific functions for plot.FFTrees(): ------
-
-
-
-# add_balls: Add balls/icon arrays to a plot ----
-
-add_balls <- function(x_lim = c(-10, 0),
-                      y_lim = c( -2, 0),
-                      n_vec   = c(20, 10),
-                      pch_vec = c(21, 21),
-                      ball_cex = 1,
-                      bg_vec  = "white",
-                      col_vec = "black",
-                      ball_lwd = .70,
-                      freq_text = TRUE,
-                      freq_text_cex = 1.2,
-                      upper_text = "",
-                      upper_text_cex = 1,
-                      upper_text_adj = 0,
-                      # rev_order = FALSE,  # is NOT used anywhere?
-                      box_col = NULL,
-                      box_bg = NULL,
-                      n_per_icon = NULL) {
-
-
-  par(xpd = TRUE)
-
-  # Add box:
-  if (is.null(box_col) == FALSE | is.null(box_bg) == FALSE) {
-
-    rect(x_lim[1],
-         y_lim[1],
-         x_lim[2],
-         y_lim[2],
-         col = box_bg,
-         border = box_col
-    )
-
-  }
-
-  # Add upper text:
-  text(mean(x_lim), y_lim[2] + upper_text_adj,
-       label = upper_text, cex = upper_text_cex
-  )
-
-  a_n <- n_vec[1]
-  b_n <- n_vec[2]
-
-  # a_p <- n_vec[1] / sum(n_vec)  # is NOT used anywhere?
-
-  box_x_center <- sum(x_lim) / 2
-  # box_y_center <- sum(y_lim) / 2      # is NOT used anywhere?
-  # box_x_width <- x_lim[2] - x_lim[1]  # is NOT used anywhere?
-
-
-  if (is.null(n_per_icon)) { # determine cases per ball/icon:
-
-    max_n_side <- max(c(a_n, b_n))
-
-    i <- max_n_side / c(1, 5, 10, 50, 100, 1000, 10000)
-    i[i > 50] <- 0
-
-    n_per_icon <- c(1, 5, 10, 50, 100, 1000, 10000)[which(i == max(i))]
-
-  }
-
-  # Determine general ball/icon locations:
-
-  a_balls <- ceiling(a_n / n_per_icon)
-  b_balls <- ceiling(b_n / n_per_icon)
-  # n_balls <- a_balls + b_balls  # is NOT used anywhere?
-
-  a_ball_x <- 0
-  a_ball_y <- 0
-  b_ball_x <- 0
-  b_ball_y <- 0
-
-  if (a_balls > 0) {
-
-    a_ball_x <- rep(-1:-10, each = 5, length.out = 50)[1:a_balls]
-    a_ball_y <- rep(1:5, times = 10, length.out = 50)[1:a_balls]
-    a_ball_x <- a_ball_x * (x_lim[2] - box_x_center) / 10 + box_x_center
-    a_ball_y <- a_ball_y * (y_lim[2] - y_lim[1]) / 5 + y_lim[1]
-
-  }
-
-  if (b_balls > 0) {
-
-    b_ball_x <- rep(1:10, each = 5, length.out = 50)[1:b_balls]
-    b_ball_y <- rep(1:5, times = 10, length.out = 50)[1:b_balls]
-    b_ball_x <- b_ball_x * (x_lim[2] - box_x_center) / 10 + box_x_center
-    b_ball_y <- b_ball_y * (y_lim[2] - y_lim[1]) / 5 + y_lim[1]
-
-  }
-
-  # if(rev_order) {
-  #
-  #   x <- b_ball_x
-  #   y <- b_ball_y
-  #
-  #   b_ball_x <- a.x.loc
-  #   b_ball_y <- a.y.loc
-  #
-  #   a_ball_x <- x
-  #   a_ball_y <- y
-  #
-  # }
-
-
-  # Add frequency text: ----
-
-  if (freq_text) {
-    text(box_x_center, y_lim[1] - 1 * (y_lim[2] - y_lim[1]) / 5, prettyNum(b_n, big.mark = ","), pos = 4, cex = freq_text_cex)
-    text(box_x_center, y_lim[1] - 1 * (y_lim[2] - y_lim[1]) / 5, prettyNum(a_n, big.mark = ","), pos = 2, cex = freq_text_cex)
-  }
-
-  # Draw balls: ----
-
-  # Noise:
-  suppressWarnings(if (a_balls > 0) {
-    points(
-      x = a_ball_x,
-      y = a_ball_y,
-      pch = pch_vec[1],
-      bg  = bg_vec[1],
-      col = col_vec[1],
-      cex = ball_cex,
-      lwd = ball_lwd
-    )
-  })
-
-  # Signal:
-  suppressWarnings(if (b_balls > 0) {
-    points(
-      x = b_ball_x,
-      y = b_ball_y,
-      pch = pch_vec[2],
-      bg  = bg_vec[2],
-      col = col_vec[2],
-      cex = ball_cex,
-      lwd = ball_lwd
-    )
-  })
-
-  par(xpd = FALSE)
-
-} # add_balls().
-
-
 # get_x_dev: Adjust rectangle width of main title(s) ----
 
 get_x_dev <- function(string, csf = .80){
@@ -450,160 +299,6 @@ get_x_dev <- function(string, csf = .80){
 
 
 
-# add_level: Add level display to a plot ----
-
-# lloc_row: Data frame with labels, size values, and locations.
-
-add_level <- function(name,
-                      sub = "",
-                      ok_val = .5,
-                      min_val = 0,
-                      max_val = 1,
-                      bottom_text = "",
-                      level_type = "line",  # user argument "level.type" set in plot() to default "bar".
-                      # needed from plot:
-                      lloc_row   = NULL,    # element == name row (of df)
-                      header_y   = NULL,
-                      header_cex = NULL) {
-
-  # Parameters:
-  rect_center_x <- lloc_row$center_x
-  rect_center_y <- lloc_row$center_y
-
-  rect_height <- lloc_row$height
-  rect_width  <- lloc_row$width
-
-  rect_bottom_y <- rect_center_y - rect_height / 2
-  rect_top_y    <- rect_center_y + rect_height / 2
-
-  rect_left_x  <- rect_center_x - rect_width / 2
-  rect_right_x <- rect_center_x + rect_width / 2
-
-  long_name <- lloc_row$long_name
-  value <- lloc_row$value
-  value_name <- lloc_row$value_name
-
-  # # Color gradient:
-  # level_col_fun <- circlize::colorRamp2(c(min_val, ok_val,  max_val),
-  #                                        colors = c("firebrick2", "yellow", "green4"),
-  #                                        transparency = .1)
-
-
-  text(x = rect_center_x, y = header_y,
-       labels = long_name, pos = 1, cex = header_cex
-  )
-
-  # text_outline(x = rect_center_x,
-  #              y = header.y.loc,
-  #              labels = long_name,
-  #              pos = 1, cex = header_cex, r = .02
-  # )
-
-  value_height <- rect_bottom_y + min(c(1, ((value - min_val) / (max_val - min_val)))) * rect_height
-
-
-  # Add filling: ----
-
-  value_s <- min(value / max_val, 1)
-
-  delta <- 1
-  gamma <- .50
-
-  value_col_scale <- delta * value_s^gamma / (delta * value_s^gamma + (1 - value_s)^gamma)
-  # value_col <- gray(1 - value_col_scale * .5)
-
-  value_col <- gray(1, .25)
-
-  # plot(seq(0, 1, .01), delta * seq(0, 1, .01) ^ gamma / (delta * seq(0, 1, .01) ^ gamma + (1 - seq(0, 1, .01)) ^ gamma))
-
-  if (level_type == "bar") {
-
-    rect(rect_left_x,
-         rect_bottom_y,
-         rect_right_x,
-         value_height,
-         # col = level_col_fun(value_s),
-         col = value_col,
-         # col = spec.level.fun(lloc_row$value),
-         border = "black"
-    )
-
-    text_outline(
-      x = rect_center_x,
-      y = value_height,
-      labels = lloc_row$value_name,
-      cex = 1.5, r = .008, pos = 3
-    )
-
-    # Add level border:
-
-    # rect(rect_left_x,
-    #      rect_bottom_y,
-    #      rect_right_x,
-    #      rect_top_y,
-    #      border = gray(.5, .5))
-  }
-
-
-  if (level_type == "line") {
-
-    # stem:
-    segments(rect_center_x,
-             rect_bottom_y,
-             rect_center_x,
-             value_height,
-             lty = 3
-    )
-
-    # horizontal platform:
-    platform.width <- .02
-
-    segments(
-      rect_center_x - platform.width,
-      value_height,
-      rect_center_x + platform.width,
-      value_height
-    )
-
-    # text label:
-    text_outline(
-      x = rect_center_x,
-      y = value_height,
-      labels = lloc_row$value_name,
-      cex = 1.5, r = 0, pos = 3
-    )
-
-    # points(rect_center_x,
-    #        value_height,
-    #        cex = 5.5,
-    #        pch = 21,
-    #        bg = "white",
-    #        col = "black", lwd = .5)
-  }
-
-  # Add subtext: ----
-
-  text(
-    x = rect_center_x,
-    y = rect_center_y - .05,
-    labels = sub,
-    cex = .8,
-    font = 1,
-    pos  = 1
-  )
-
-  # Add bottom text: ----
-
-  text(
-    x = rect_center_x,
-    y = rect_bottom_y,
-    labels = bottom_text,
-    pos = 1
-  )
-
-} # add_level().
-
-
 # pretty_dec: Print pretty decimal values ----
 
 pretty_dec <- function(x) {