Question

I want to add legends in a subplot, bu only for certain plots.
Here is my code :

for j = 1:length(FL)
  for i = 1:length(index_list)
    pos=pos+1;
    subplot(size(FL,1),length(index_list), pos)
    legend(num2str(ms_list(i)), 'Location', 'NorthOutside');
    imagesc(imread(FL{j,:},index_list(i)))
    if i==1
        legend(FL(j),'Location', 'WestOutside')

  end 
end

The subplot contains frames extracted from multiframes .tif files. Indexes of the wanted frames are in index_list (the columns). Path to the files wanted are in FL (the rows). What I want to add on the figure is the name of the file at the left of each row and the frame index for each image plotted. ms_list contains the equivalent in milliseconds of the indexes, thats actually what I want to show.
Doing like that returns “Plot empty” at each passage in the loop.

Any idea ?

Thanks

JC

Answer 1

From your description and code, it seems that legend isn’t what you want; rather, you want a title (above the plot) and ylabel (left of certain plots). legend is to give labels to particular objects inside the plot, such as a line series for example.

for j = 1:length(FL)
  for i = 1:length(index_list)
    pos=pos+1;
    subplot(size(FL,1),length(index_list), pos)
    title(num2str(ms_list(i))); %#<---title here
    imagesc(imread(FL{j,:},index_list(i)))
    if i==1
        ylabel(FL(j)) %#<---ylabel here    
    end 
  end
end

The reason you were getting an error is that you were applying legend to an empty set of axes. legend labels the children of axes; no children, nothing to label, hence the error.