Add pivot longer and wider

docs/make.jl

@@ -1,5 +1,8 @@
 using Documenter, QueryOperators
 
+# Configure DocMeta to automatically import QueryOperators for all doctests
+DocMeta.setdocmeta!(QueryOperators, :DocTestSetup, :(using QueryOperators); recursive=true)
+
 makedocs(
 	modules = [QueryOperators],
 	sitename = "QueryOperators.jl",
@@ -8,7 +11,8 @@ makedocs(
 	),
 	pages = [
         "Introduction" => "index.md"
-    ]
+    ],
+	warnonly = [:missing_docs]
 )
 
 deploydocs(

src/NamedTupleUtilities.jl

@@ -185,11 +185,11 @@ end
     oftype(a::NamedTuple, b::DataType)
 Returns a NamedTuple which retains the fields whose elements have type `b`.
 ```jldoctest
-julia> QueryOperators.NamedTupleUtilities.oftype((a = [4,5,6], b = [3.,2.,1.], c = ["He","llo","World!"]), Val(Int64))
-(a = [4, 5, 6],)
-julia> QueryOperators.NamedTupleUtilities.oftype((a = [4,5,6], b = [3.,2.,1.], c = ["He","llo","World!"]), Val(Number))
-(a = [4, 5, 6], b = [3., 2., 1.])
-julia> QueryOperators.NamedTupleUtilities.oftype((a = [4,5,6], b = [3.,2.,1.], c = ["He","llo","World!"]), Val(Float32))
+julia> QueryOperators.NamedTupleUtilities.oftype((a = 4, b = 3., c = "He"), Val(Int64))
+(a = 4,)
+julia> QueryOperators.NamedTupleUtilities.oftype((a = 4, b = 3., c = "He"), Val(Number))
+(a = 4, b = 3.0)
+julia> QueryOperators.NamedTupleUtilities.oftype((a = 4, b = 3., c = "He"), Val(Float32))
 NamedTuple()
 ```
 """

src/QueryOperators.jl

@@ -16,14 +16,14 @@ include("enumerable/enumerable_join.jl")
 include("enumerable/enumerable_groupjoin.jl")
 include("enumerable/enumerable_orderby.jl")
 include("enumerable/enumerable_map.jl")
-include("enumerable/enumerable_gather.jl")
 include("enumerable/enumerable_filter.jl")
 include("enumerable/enumerable_mapmany.jl")
 include("enumerable/enumerable_defaultifempty.jl")
 include("enumerable/enumerable_count.jl")
 include("enumerable/enumerable_take.jl")
 include("enumerable/enumerable_drop.jl")
 include("enumerable/enumerable_unique.jl")
+include("enumerable/enumerable_pivot.jl")
 include("enumerable/show.jl")
 
 include("source_iterable.jl")

src/enumerable/enumerable_pivot.jl

@@ -0,0 +1,243 @@
+# ===== pivot_longer =====
+# Transforms wide data to long format by pivoting named columns into key/value rows.
+
+struct EnumerablePivotLonger{T, S, COLS, ID_COLS} <: Enumerable
+    source::S
+end
+
+Base.IteratorSize(::Type{EnumerablePivotLonger{T,S,COLS,ID_COLS}}) where {T,S,COLS,ID_COLS} = haslength(S)
+
+Base.eltype(::Type{EnumerablePivotLonger{T,S,COLS,ID_COLS}}) where {T,S,COLS,ID_COLS} = T
+
+Base.length(iter::EnumerablePivotLonger{T,S,COLS,ID_COLS}) where {T,S,COLS,ID_COLS} =
+    length(iter.source) * length(COLS)
+
+function pivot_longer(source::Enumerable, cols::NTuple{N,Symbol};
+        names_to::Symbol=:variable, values_to::Symbol=:value) where N
+    N == 0 && error("pivot_longer requires at least one column to pivot")
+    TS = eltype(source)
+    all_fields = fieldnames(TS)
+    id_cols = tuple((f for f in all_fields if f ∉ cols)...)
+
+    value_type = reduce(promote_type, (fieldtype(TS, c) for c in cols))
+
+    out_names = (id_cols..., names_to, values_to)
+    out_types = Tuple{(fieldtype(TS, f) for f in id_cols)..., Symbol, value_type}
+    T = NamedTuple{out_names, out_types}
+
+    return EnumerablePivotLonger{T, typeof(source), cols, id_cols}(source)
+end
+
+# Type-stable row construction: generates a static if/elseif chain over COLS at compile time.
+@generated function _pivot_longer_row(row::NamedTuple, ::Val{ID_COLS}, col_idx::Int,
+        ::Val{COLS}, ::Type{T}) where {ID_COLS, COLS, T}
+    id_exprs = [:(getfield(row, $(QuoteNode(f)))) for f in ID_COLS]
+    value_type = fieldtype(T, length(ID_COLS) + 2)  # fields: id..., names_to, values_to
+
+    branches = Expr[]
+    for (i, col) in enumerate(COLS)
+        push!(branches, quote
+            if col_idx == $i
+                return T(($(id_exprs...), $(QuoteNode(col)),
+                    convert($value_type, getfield(row, $(QuoteNode(col))))))
+            end
+        end)
+    end
+
+    return quote
+        $(branches...)
+        error("pivot_longer: col_idx out of range")
+    end
+end
+
+function Base.iterate(iter::EnumerablePivotLonger{T,S,COLS,ID_COLS}) where {T,S,COLS,ID_COLS}
+    source_ret = iterate(iter.source)
+    source_ret === nothing && return nothing
+    row, source_state = source_ret
+    out = _pivot_longer_row(row, Val(ID_COLS), 1, Val(COLS), T)
+    return out, (row=row, source_state=source_state, col_idx=1)
+end
+
+function Base.iterate(iter::EnumerablePivotLonger{T,S,COLS,ID_COLS}, state) where {T,S,COLS,ID_COLS}
+    next_idx = state.col_idx + 1
+    if next_idx <= length(COLS)
+        out = _pivot_longer_row(state.row, Val(ID_COLS), next_idx, Val(COLS), T)
+        return out, (row=state.row, source_state=state.source_state, col_idx=next_idx)
+    else
+        source_ret = iterate(iter.source, state.source_state)
+        source_ret === nothing && return nothing
+        row, source_state = source_ret
+        out = _pivot_longer_row(row, Val(ID_COLS), 1, Val(COLS), T)
+        return out, (row=row, source_state=source_state, col_idx=1)
+    end
+end
+
+# ===== pivot_wider =====
+# Transforms long data to wide format by spreading a key column into multiple value columns.
+
+struct EnumerablePivotWider{T} <: Enumerable
+    results::Vector{T}
+end
+
+Base.IteratorSize(::Type{EnumerablePivotWider{T}}) where T = Base.HasLength()
+
+Base.eltype(::Type{EnumerablePivotWider{T}}) where T = T
+
+Base.length(iter::EnumerablePivotWider{T}) where T = length(iter.results)
+
+function pivot_wider(source::Enumerable, names_from::Symbol, values_from::Symbol;
+        id_cols=nothing)
+    TS = eltype(source)
+    all_fields = fieldnames(TS)
+
+    id_col_names = if id_cols === nothing
+        tuple((f for f in all_fields if f != names_from && f != values_from)...)
+    else
+        tuple(id_cols...)
+    end
+
+    val_type = fieldtype(TS, values_from)
+    out_val_type = DataValues.DataValue{val_type}
+
+    all_rows = collect(source)
+
+    # Collect unique name values in order of first appearance
+    seen_names = OrderedDict{Symbol, Nothing}()
+    for row in all_rows
+        seen_names[Symbol(getfield(row, names_from))] = nothing
+    end
+    new_col_names = tuple(keys(seen_names)...)
+
+    out_names = (id_col_names..., new_col_names...)
+    out_types = Tuple{(fieldtype(TS, f) for f in id_col_names)...,
+                      (out_val_type for _ in new_col_names)...}
+    T = NamedTuple{out_names, out_types}
+
+    # Group rows by their id-column values
+    id_to_values = OrderedDict{Any, Dict{Symbol, val_type}}()
+    for row in all_rows
+        id_key = ntuple(i -> getfield(row, id_col_names[i]), length(id_col_names))
+        name_sym = Symbol(getfield(row, names_from))
+        value = getfield(row, values_from)
+        if !haskey(id_to_values, id_key)
+            id_to_values[id_key] = Dict{Symbol, val_type}()
+        end
+        id_to_values[id_key][name_sym] = value
+    end
+
+    na = out_val_type()
+    results = Vector{T}(undef, length(id_to_values))
+    for (i, (id_key, vals_dict)) in enumerate(id_to_values)
+        new_vals = ntuple(
+            j -> haskey(vals_dict, new_col_names[j]) ?
+                out_val_type(vals_dict[new_col_names[j]]) : na,
+            length(new_col_names))
+        results[i] = T((id_key..., new_vals...))
+    end
+
+    return EnumerablePivotWider{T}(results)
+end
+
+# ===== Column selector resolution =====
+# Resolves a tuple of column names from a NamedTuple type according to a list of
+# selector instructions (encoded in a Val type parameter for compile-time evaluation).
+#
+# Each instruction is a 2-tuple (op, arg):
+#   (:include_name,       sym)         — include field by name
+#   (:exclude_name,       sym)         — exclude field by name
+#   (:include_position,   idx)         — include field at 1-based position
+#   (:exclude_position,   idx)         — exclude field at 1-based position
+#   (:include_startswith, prefix_sym)  — include fields whose name starts with prefix
+#   (:exclude_startswith, prefix_sym)  — exclude fields whose name starts with prefix
+#   (:include_endswith,   suffix_sym)  — include fields whose name ends with suffix
+#   (:exclude_endswith,   suffix_sym)  — exclude fields whose name ends with suffix
+#   (:include_occursin,   sub_sym)     — include fields whose name contains sub
+#   (:exclude_occursin,   sub_sym)     — exclude fields whose name contains sub
+#   (:include_range,      (from, to))  — include field names from :from to :to (inclusive)
+#   (:include_range_idx,  (a, b))      — include fields at 1-based positions a through b
+#   (:include_all,        :_)          — include all remaining fields
+#
+# If all instructions are "exclude" ops, the starting set is ALL field names; otherwise
+# the starting set is empty and "include" instructions accumulate into it.
+@generated function _resolve_pivot_cols(::Type{NT}, ::Val{instructions}) where {NT<:NamedTuple, instructions}
+    all_names = collect(fieldnames(NT))
+
+    include_ops = (:include_name, :include_position, :include_startswith,
+                   :include_endswith, :include_occursin, :include_all,
+                   :include_range, :include_range_idx)
+    has_positive = any(inst[1] ∈ include_ops for inst in instructions)
+
+    result = has_positive ? Symbol[] : copy(all_names)
+
+    for inst in instructions
+        op  = inst[1]
+        arg = inst[2]
+
+        if op == :include_all
+            for n in all_names
+                n ∉ result && push!(result, n)
+            end
+        elseif op == :include_name
+            arg ∉ result && push!(result, arg)
+        elseif op == :exclude_name
+            filter!(!=( arg), result)
+        elseif op == :include_position
+            n = all_names[arg]
+            n ∉ result && push!(result, n)
+        elseif op == :exclude_position
+            n = all_names[arg]
+            filter!(!=(n), result)
+        elseif op == :include_startswith
+            for n in all_names
+                if Base.startswith(String(n), String(arg)) && n ∉ result
+                    push!(result, n)
+                end
+            end
+        elseif op == :exclude_startswith
+            filter!(n -> !Base.startswith(String(n), String(arg)), result)
+        elseif op == :include_endswith
+            for n in all_names
+                if Base.endswith(String(n), String(arg)) && n ∉ result
+                    push!(result, n)
+                end
+            end
+        elseif op == :exclude_endswith
+            filter!(n -> !Base.endswith(String(n), String(arg)), result)
+        elseif op == :include_occursin
+            for n in all_names
+                if Base.occursin(String(arg), String(n)) && n ∉ result
+                    push!(result, n)
+                end
+            end
+        elseif op == :exclude_occursin
+            filter!(n -> !Base.occursin(String(arg), String(n)), result)
+        elseif op == :include_range
+            from_sym, to_sym = arg
+            in_range = false
+            for n in all_names
+                n == from_sym && (in_range = true)
+                in_range && n ∉ result && push!(result, n)
+                n == to_sym && (in_range = false; break)
+            end
+        elseif op == :include_range_idx
+            from_idx, to_idx = arg
+            for i in from_idx:to_idx
+                n = all_names[i]
+                n ∉ result && push!(result, n)
+            end
+        end
+    end
+
+    names = tuple(result...)
+    return :($names)
+end
+
+function Base.iterate(iter::EnumerablePivotWider{T}) where T
+    isempty(iter.results) && return nothing
+    return iter.results[1], 2
+end
+
+function Base.iterate(iter::EnumerablePivotWider{T}, state) where T
+    state > length(iter.results) && return nothing
+    return iter.results[state], state + 1
+end

src/operators.jl

@@ -26,12 +26,6 @@ macro filter(source, f)
     :(QueryOperators.filter($(esc(source)), $(esc(f)), $(esc(q))))
 end
 
-function gather end
-
-macro gather(source, withIndex = False)
-	:(groupby($(esc(source)), $(esc(withIndex))))
-end
-
 function groupby end
 
 macro groupby(source,elementSelector,resultSelector)
@@ -129,3 +123,7 @@ macro unique(source, f)
     q = Expr(:quote, f)
     :(unique($(esc(source)), $(esc(f)), $(esc(q))))
 end
+
+function pivot_longer end
+
+function pivot_wider end