How to determine if an axes already as a colorbar?

Question

I would like to determine if an axes already has a colorbar. I have code which plots many objects on the same axes, but I only want to create and define the colorbar once to make things more efficient. I've tried looking for a ColorBar object as a child of the figure handle, but I have multiple subplots in the same figure, and each may or may not need their own colorbar. Is there a way to determine if a particular axes has a colorbar associated with it?

Answer 1

Credit to Voss at MATLAB Answers

There is a hidden axes property called 'Colorbar', which you can use.

% two axes, one with colorbar, one without
ax = subplot(2,1,1);
plot(1:10)
colorbar()
ax(2) = subplot(2,1,2);
plot(1:10)

 ax1_has_colorbar = ~isempty(ax(1).Colorbar)

Returns true

 ax2_has_colorbar = ~isempty(ax(2).Colorbar)

Returns false

Answer 2

you can use findobj for that, for example

figure
subplot(2,2,1); plot(rand(4));
subplot(2,2,2); imagesc(rand(10)); colorbar
subplot(2,2,3); plot(rand(3)); legend('a','b','c')
subplot(2,2,4); imagesc(rand(32)); colorbar

h = get(gcf,'children');
axes_ind      =  findobj(h,'type','Axes');
legend_ind    =  findobj(h,'type','Legend');
colorbar_ind  =  findobj(h,'type','Colorbar');

you can check h and also see that colorbar_ind now has access to your colorbars...

note that once you create a colorbar, you create an independent object at some position in the figure, it is not a child of an axes object.