standard deviation of same values in a matrix
1 view (last 30 days)
Show older comments
Hello,
I couldn't find anything which could help me with my problem.
I have a matrix (n x 2) like shown below:
I want to calculate the standard deviation of column 2 for all records which have the same valaue in column 1. So I get this:
Is there a smart way to do this? Maybe is several steps?
Thanks!
0 Comments
Answers (2)
the cyclist
on 30 Nov 2015
Edited: the cyclist
on 30 Nov 2015
M = [5 0.30;
5 0.35;
7 0.50;
7 0.51;
9 0.98;
9 0.87;
9 0.71];
[uniqueM,idxToUnique,idxFromUniqueBackToAll] = unique(M(:,1));
S = accumarray(idxFromUniqueBackToAll,M(:,2),[],@std)
stdDevM = [uniqueM,S]
2 Comments
the cyclist
on 1 Dec 2015
The best form of thanks is accepting the solution, which rewards the person who helped you, and also points future users to good answers.
See Also
Categories
Find more on Creating and Concatenating 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!