`heatmap` missing size checks

[ericphanson]

• what version of Makie are you running? (]st -m Makie) v0.24.8
• can you reproduce the bug with a fresh environment ? (]activate --temp; add Makie)
• What platform + GPU are you on? macos cpu
• Which backend are you using? (GLMakie, CairoMakie, WGLMakie, RPRMakie) CairoMakie
• Please provide an minimal example of the failing code. If the problem is with the visualization, please provide a picture or video of it.

Here is a small modification of the example from here:

using CairoMakie
f = Figure()
ax = Axis(f[1, 1])

centers_x = 1:5 # length 5
centers_y = 6:10 # length 5
data = reshape(1:30, 6, 5) # 6 x 5

heatmap!(ax, centers_x, centers_y, data) # no error

scatter!(ax, [(x, y) for x in centers_x for y in centers_y], color=:white, strokecolor=:black, strokewidth=1)

f

I would want heatmap! to error as length(x) != size(data, 1).

The docs say:

Plots a heatmap as a collection of rectangles. x and y can either be of length i and j where (i, j)
is size(matrix), in this case the rectangles will be placed around these grid points like voronoi
cells. Note that for irregularly spaced x and y, the points specified by them are not centered
within the resulting rectangles.

x and y can also be of length i+1 and j+1, in this case they are interpreted as the edges of the
rectangles.

but here x is size(matrix, 1) - 1, not +1.

[AmanKashyap0807]

Hi @ericphanson

I’m a 3rd year B.Tech student and I’m trying to start contributing to Makie. I was going through the heatmap docs and also checking a bit of the conversion code, and I agree it feels confusing that heatmap accepts x/y lengths which are neither size(data) (center-based) nor size(data)+1 (edge-based), and still plots without any error.

From what I understood, a simple fix could be to add a check so that if length(x) and length(y) don’t match either of these two valid cases, Makie should throw a clear error message early (instead of silently continuing).

Just one thing I want to confirm with you (so I implement it in the expected way):

In this situation, do you prefer Makie to throw a strict error immediately (like DimensionMismatch / ArgumentError), or would you prefer a warning / fallback behaviour?
If you’re okay with it, I can try to work on this issue and add a small test also. Please let me know if there is any specific style/message you want for the error, or any edge case you want me to keep in mind.

Thanks!