MATLAB Answers

caxis with HeatMap?

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D
D on 6 Jul 2011
I'd like to specify the scale of the colormap used for a heat map.
It seems that something like caxis would be appropriate but it doesn't appear to work. All of the examples are for functions like surf.
Is there a way to use caxis to do this, or something else that would work for a heat map?
Thanks very much.

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Accepted Answer

Patrick Kalita
Patrick Kalita on 6 Jul 2011
Maybe I should have mentioned this in the answer to your previous question, but maybe the HeatMap object's plot method would be useful here. That method will render the heatmap image into a standard MATLAB axes. Then you can use all the standard graphics functions like colorbar and caxis with it.
For example:
data = gallery('invhess',20);
hm = HeatMap(data);
ax = hm.plot; % 'ax' will be a handle to a standard MATLAB axes.
colorbar('Peer', ax); % Turn the colorbar on
caxis(ax, [-3 10]); % Adjust the color limits

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D
D on 19 Jul 2011
Hello. This worked beautifully, in terms of what I asked. I have a few more questions, though, that I was hoping you might be able to answer.
Some of my labels on the heat map are getting cut off, and this seems arbitrary: i.e. the last letter of a shorter label is cut off, but the longer labels are fine. Is there a way to add extra space between the plot and the labels?
How do I title the figures directly, instead of the heat maps, without using the property editor?
Finally, there appears to be a lot of grey space surrounding the plot area in the figures. Is there a way to get rid of this, short of cropping?
Thanks again for your help.
D
D on 19 Jul 2011
Just to clarify: the extra grey space shows up when I try to resize the figure. The heat map expands a little, but most of the expansion in the figure window is the grey space.
Also, I have code for the title, but it does this strange thing where every part of the string is on a different line.
title(ax, ['Plot ' num2str(p) ': ' list(p)]);
where p is an index for this particular plot (I'm doing these in a loop) and where list = {'abcd'; 'efgh'}.
So, it should read something like: "Plot 1: abcd" and "Plot 2: efgh". Instead I get
Plot
1
:
abcd
At first, I thought this might be because the figure is too small, but after expanding the figure, the title didn't expand to the full length of the plot area.

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