Compress down a 1000x1000 matrix into a 100x100 matrix
54 views (last 30 days)
Show older comments
Ahmed Abdulla
on 7 Jun 2020
Commented: larasupernovae
on 3 Mar 2022
I have a 1000x1000 matrix that contains various values. I would like to compress it down into a 100 by 100 matrix by averaging each 10 by 10 cell's values into 1, but im not really sure how to go about doing this
0 Comments
Accepted Answer
Ameer Hamza
on 7 Jun 2020
Edited: Ameer Hamza
on 7 Jun 2020
If you have image processing toolbox
M = rand(1000, 1000);
M_new = blockproc(M, [10 10], @(x) mean(x.data, 'all'))
Alternative Solution 1: (surprisingly the fastest)
M_new = conv2(M, ones(10)/100, 'valid');
M_new = M_new(1:10:end, 1:10:end);
Alternative Solution 2:
M_C = mat2cell(M, 10*ones(1,100), 10*ones(1,100));
M_new = cellfun(@(x) mean(x, 'all'), M_C);
Alternative Solution 3:
M_new = zeros(size(M)/10);
for i=1:100
for j=1:100
M_new(i, j) = mean(M(10*(i-1)+1:10*i,10*(j-1)+1:10*j), 'all');
end
end
2 Comments
Robert Jansen
on 24 Mar 2021
Amazing array of solutions. These all give the same results. The last one is surprisingly fast too. Thanks.
More Answers (2)
David Hill
on 7 Jun 2020
count=1;
for col=1:100:1000
for row=1:100:1000
newMatrix(count)=mean(yourMatrix(row:row+99,col:col+99),'all');
count=count+1;
end
end
newMatrix=reshape(newMatrix,10,[]);
0 Comments
See Also
Categories
Find more on Resizing and Reshaping Matrices in Help Center and File Exchange
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!