How can I color individual patches in my contour plot in MATLAB 7.10 (R2010a)?

I would like to generate a filled contour plot with a single contour line (at z=0) and two different colors, where neither color is white. When I run the COUNTROUF command, one of the regions always seems to plot as white. I would like to change the white color to some other colors.

Reproduction Steps:

[x,y,z] = peaks;

contourf(x,y,z,[0 0])

Answer 1

[MathWorks Support Team]

This is an expected behavior. Since we are displaying the contour plot at z = 0, the white patches we get from the reproduction steps you provided are a part of the axes background. The axes background color can be set in the command text or from the axes properties editor. The small circular patch at the center, though has level of zero, is an individual patch so needs to be colored separately. Execute the following MATLAB code to generate the contour plot with two colors:

[x,y,z] = peaks;

[c,h] = contourf(x,y,z,[0 0])   

% c contains contour matrix and h is the handle

ccc = get(h, 'children');   % Get different patches

set(ccc(1),'facecolor','r')   

% Center patch. Color can be changed from red ‘r’ to other colors

set(ccc(2),'facecolor',[rand(1,3)])   

% Left and bottom patches filled with a random color

set(gca,'color','r')   % Set background color

[Johannes Korsawe]

Does not work any longer with release 2014b.

[Johannes Korsawe]

Does not work any longer with release 2014b.