Standard deviation of a 3-d matrix
2 views (last 30 days)
Show older comments
hi I have a matrix with size(y)=(200*1*4). I want to calculate the std for each (200*1) vector separately. When I used "std(y(y>0)), it gave me an value but I want in fact 4 values for each 200*1 vector size. How can I write the code to give me the std for each inner vector without "for",and ....
Thanks for your help
0 Comments
Accepted Answer
Kye Taylor
on 13 Jul 2012
If y is 200-by-1-by-4, you can get rid of the singleton dimension using
y2D = squeeze(y);
then compute the 4 different standard deviations using
the4Sigmas = std(y2D);
3 Comments
Kye Taylor
on 13 Jul 2012
Edited: Kye Taylor
on 13 Jul 2012
Sure, but next time, ask a brand new question.
I would then use a for loop
sigmasPositive = zeros(1,4);
for j = 1:size(y2D,2)
idxOfInterest = y2D(:,j) > 0;
sigmasPositive(j) = std(y2D(idxOfInterest,j));
end
or you can avoid the loop using
z = mat2cell(y2D,size(y2D,1),ones(1,size(y2D,2)));
sigmasPositiveNoLoop = cellfun(@(c)std(c(c>0)),z);
More Answers (0)
See Also
Categories
Find more on Creating and Concatenating Matrices in Help Center and File Exchange
Products
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!