How can one display multiple Heatmaps in one figure on the same scale?

Hello,

I have spectral data from three components for several events. I have a short routine to plot the spectra:

% heater1

% Get the spectra and frequencies
spectra         = Calc_All;
freeks          = 1:size(spectra,2);
% Pick events
picked_events   = ident(selections_from_table);
%Choose the event labels to use (e.g., file_name)
event_labels    = input_struc.file_name(picked_events);
The
figure('Name','Spectral Map','NumberTitle','off','MenuBar','none','ToolBar','none');

for compo = 1:3
    subplot(1,3,compo)
    this_spec   = squeeze(spectra(compo,:,:));
    hdl         = heatmap(freeks,event_labels,this_spec');
end

If I plot this just as it is, I get the following:

where (I guess it's hard to see) the max levels on each one are different, and so is the shading.

I don't know if fixing a Ylim for each one will work, since that's not known beforehand. Is there a simple way around this? I didn't see an "Answer" here. heatmap() is quite involved!

Thanks!

Doug

Answer 1

[Voss]

You can specify the ColorLimits of all three heatmaps after they are created.

Here's a demonstration with some random data:

for compo = 1:3
    subplot(1,3,compo)
    % 1st heatmap ranges between 1 and 2, 2nd is [2 3], 3rd is [3 4]
    % in order to see the effect of using common ColorLimits
    this_spec   = compo+rand(5,10);
    hdl(compo)  = heatmap(1:5,1:10,this_spec');
end

if numel(hdl) > 1
    c_lim = get(hdl,'ColorLimits');
    c_lim = vertcat(c_lim{:});
    c_lim = [min(c_lim(:,1)) max(c_lim(:,2))];
    set(hdl,'ColorLimits',c_lim);
end

[Voss]

And since they all have the same ColorLimits, you may want to turn off the colorbars for all but one of them:

for compo = 1:3
    subplot(1,3,compo)
    this_spec   = compo+rand(5,10);
    hdl(compo)  = heatmap(1:5,1:10,this_spec');
end

if numel(hdl) > 1
    c_lim = get(hdl,'ColorLimits');
    c_lim = vertcat(c_lim{:});
    c_lim = [min(c_lim(:,1)) max(c_lim(:,2))];
    set(hdl,'ColorLimits',c_lim);
    set(hdl(1:end-1),'ColorbarVisible','off')
end

[Douglas Anderson]

Fantastic!  Thank you!!!!

[Voss]

You're welcome!

[Douglas Anderson]

One more question: setting 'ColorbarVisible' to 'off' for all but "end" is good, but then how do you clear the Ylabel for 2:end? All rows have the same data.

Thanks again!

Doug

[Voss]

You can do that like this:

% create the heatmaps, same as before:
for compo = 1:3
    subplot(1,3,compo)
    this_spec   = compo+rand(5,10);
    hdl(compo)  = heatmap(1:5,1:10,this_spec');
end

% update ColorLimits, same as before:
if numel(hdl) > 1
    c_lim = get(hdl,'ColorLimits');
    c_lim = vertcat(c_lim{:});
    c_lim = [min(c_lim(:,1)) max(c_lim(:,2))];
    set(hdl,'ColorLimits',c_lim);
    set(hdl(1:end-1),'ColorbarVisible','off')
end

% I make up some long text labels for the first heatmap:
set(hdl(1),'YDisplayLabels',sprintfc('some long text %d',1:10))

% and clear out the others:
set(hdl(2:end),'YDisplayLabels',strings(10,1))

[Douglas Anderson]

Great! Thank you again, this is a huge help (both for the project and in understanding).

[Voss]

You're welcome!

By the way, here's the documentation for changing properties of heatmaps:

https://www.mathworks.com/help/matlab/ref/matlab.graphics.chart.heatmapchart-properties.html