MATLAB: Plotting separate parts of a column on different figures

plotting

I have a large matrix. In the 3rd column, I have my "eta" values. In my 4th column, I have "r" values. In my 8th column, I have "g" values.
Eta is the same as you go down column for a while. How can I plot g vs. r as long as eta is the same, then make a new plot with g vs r anytime eta changes?
Maybe the matrix needs to be reshaped first? Note that the number of eta values that are the same can change.

Best Answer

Following your description "I have a large matrix. In the 3rd column, I have my "eta" values. In my 4th column, I have "r" values. In my 8th column, I have "g" values", here is one simple loop:
% Random fake data with contiguous eta groups:
mat = rand(32,8);
mat(:,3) = sort(randi(9,32,1));
% Detect eta groups (i.e. changes in eta):
bnd = find([true;diff(mat(:,3));true]);
% Plot data for each eta group:
for k = 1:numel(bnd)-1
	figure() % using ONE figure is usually simpler.
	idx = bnd(k):bnd(k+1)-1;
	G = mat(idx,8);
	R = mat(idx,4);
	plot(R,G) % or plot(G,R), whatever you want
	title(sprintf('eta = %d',mat(bnd(k),3)))
end
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