Hi evrybody, I’m trying to overlay a scatter plot with a heatmap using Plots.jl but I can’t figure it out how heatmap is oriented (or find much documentation on the plots.jl heatmap function).
The heat map seems turned by 90 degrees (or transposed, transposing the heat-value matrix seems to fix the issue). Maybe it fills row-wise from the top left corner while reading the array column-wise?
Here is an example showing the problem
n_points = 100 w = [4, 0.7, -2.3] σ(a) = 1 / (1 + exp(-a)) x_data = randn(n_points) y_data = randn(n_points) y_data[1:n_points÷2] .+= 8 labels = [round(σ(p'*w)) for p in eachrow([ones(n_points) x_data y_data])] plt = scatter(x_data, y_data, zcolor=labels) xs = range(-4, 3, length=100) ys = range(-4, 11, length=100) grid = [[1, x, y] for x in xs, y in ys] heat = [σ(p'*w) for p in grid] heatmap!(plt, xs, ys, heat, alpha=0.5) # this doesn't look right # now transpose and it does plt = scatter(x_data, y_data, zcolor=labels) heatmap!(plt, xs, ys, transpose(heat), alpha=0.5)
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