how to create different matrices?

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i have 30,000 rand value that i want to separate 400 to 400...then i wanna plot them but the x axis should start at 0 not 400 or 800 or...any help please?
  3 Comments
arian hoseini
arian hoseini on 7 Dec 2022
yes sorry i meant i need the first 400 num of that matrix(30000) to be plot start from 1 to 400 next one should be 401 to 800 then...and i need to save these plot with saveas(gcf,[num2str(i),'.jpg']) and i need the first 400 num in a matrix then next one in another matrix...
arian hoseini
arian hoseini on 7 Dec 2022
for the matrix lets say i have 10 num in a matrix but i want to change it into 10 matrices...
[1 2 3 4 5 6 7 8 9 10]
[1]
[2]
.
.
[10]

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Accepted Answer

Jonas
Jonas on 7 Dec 2022
you could split them into multiple 400x1 vectors by this
data=rand(30000,1);
data=reshape(data,400,1,[]);
size(data)
ans = 1×3
400 1 75
you can then get each vector using indexing data(:,:,idx)
for idx=1%:75 % commented out to avoid to much plotting here
plot(0:399,data(:,:,idx));
% saveas(gcf,[num2str(idx),'.jpg']);
end
  11 Comments
DGM
DGM on 7 Dec 2022
Edited: DGM on 7 Dec 2022
You can do that, but you'll have to figure out how you want the image shaped, whether you want the ticks plotted, etc.
npoints = 30000; % or some multiple of 400
blocklen = 400;
startidx = 0;
% generate x,y
x = startidx:startidx+npoints-1;
y = rand(npoints,1);
% reshape
x = reshape(x,blocklen,[]);
y = reshape(y,blocklen,[]);
% plot and capture
nframes = size(x,2);
allframes = cell(nframes,1);
for k = 1:nframes
plot(x(:,k),y(:,k))
allframes{k} = frame2im(getframe(gcf));
end
This will save all the frames in a cell array. Alternatively, you can write them using imwrite().
Note that as images, the details of the start/end indices is moot, since the ticks aren't going to show that detail well enough for anyone to tell. You could always try to enforce the exact axis limits, but it's still not going to help much.
% place this in the loop between plotting and capture
xlim(x([1 end],k))
ylim([0 1])

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