MATLAB: Quantized colorbar

colorbargraphingplotting

I would like a colorbar that only shows the colors of numbers that exist in the dataset.
Example:
x = -2*pi:0.01:2*pi;
y = x;
[X Y] = meshgrid(x,y);
Z = sign(round(cos(X).*cos(Y)));
imagesc(x,y,Z);colorbar;
There are only 3 possible numbers in the output matrix. Unfortunately, the colorbar will still show a full gradient.
I would appreciate a method for generating a colorbar with only the levels that are present.

Best Answer

X = sign(round((rand(10)-.5)*2));
imagesc(X);
un_X = unique(X);
colormap(cool(length(un_X)));
H = colorbar;
set(H,'ytick',un_X);
Manually set the colormap and the colorbar's ytick to the unique values of X.
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