I had a similar issue of only wanting to plot the bottom half of the matrix. Like you said H H the plotmatrix function outputs objects so I just used the function like normal and then deleted the handles. For me it was the visual presentation of the chart, but I don't think this will solve the problem of slowness due to the large amount of data (unless you are zomming/panning around looking at the data once its in the plot).
Lets take a 4x4 plot matrix. The excel plot below is how gplotmatrix assigned the axes handles. The axes handles start at 2 and go right to left. I wanted to delete the ones in yellow because they present the same data as the lower half just with flipped axes.
So I needed to collect each handle I didn't want and then deleted them.
h = figure(123);
% gplotmatrix(...) % this is obviously uncommented, I just don't know what your inputs are
M = length(gplotNAMES); % M length of matrix
ii=1; indexEND=0; % initial counters
while (M-ii-1) >= 0
indexSTART = indexEND + ii; % start index for each row
indexEND = indexSTART + (M-ii-1); % end index for each row
index2delete{ii} = indexSTART:indexEND; % collect the indices for each row (ii)
ii=ii+1;
end
% convert cell to a vector, you just need all the indices. Not necessarily by row
indDELETE = cell2mat(index2delete)+1; % add 1 because the axes objects start at 2
delete(h.Children(indDELETE)) % delete all handles in indDELETE
I hope this helps! I know your submission is ~2 years old, but I figured it would be nice to see an answer at some point!
-Ryan
