How to overlay a pcolor plot with a contour plot that uses a different colormap?

Question

Minimum example that does not achieve it:

[X,Y,Z] = peaks;
figure;
pcolor(X,Y,Z);
shading flat;
hold all;
axes;
contour(X,Y,Z);
colormap gray;  % this should only apply to the contour plot axes...
axis off;       % ... but it doesn't

This shows both the contour plot and the pseudo colour plot in the grayscale colourmap. However, what I want to achieve is only turning the contours gray.

This is just a minimalistic example, in reality the contour plot is of different data that has a different range, so two independent caxis settings are required as well.

Answer 1

You can fix the problem by catenating two colormaps, and making sure that the values of the functions are such that they access the right part of the colormap:

cm = [jet(64);gray(64)];
figure,
pcolor(X,Y,Z)
shading flat
hold on
%# Z in the contour starts after the maximum
%# of Z in pcolor
contour(X,Y,Z-min(Z(:))+max(Z(:))+2,'LineWidth',2)
%# apply the colormap
colormap(cm)

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