Finding element with max value in each row of a matrix
1 view (last 30 days)
Show older comments
Konstantinos
on 4 Dec 2014
Commented: Konstantinos
on 4 Dec 2014
How can I find the 4 elements with the largest values in each row of a matrix ? Moreover, I would like to know the exact position of them in each row.
i.e. A(2X8) = [ 1 2 3 4 8 5 2 9 ; 5 6 4 7 9 1 1 2; ]
For the above matrix the answer would be:
1st row max values elements: 4, 8, 5, 9
1st row position of these elements: 4, 5, 6, 8
2nd row max values elements: 5, 6, 7, 9
2nd row position of these elements: 1, 2, 4, 5
Any help could be useful.
Thanks in advance!
0 Comments
Accepted Answer
Azzi Abdelmalek
on 4 Dec 2014
Edited: Azzi Abdelmalek
on 4 Dec 2014
a=[ 1 2 3 4 8 5 2 9 ; 5 6 4 7 9 1 1 2; ]
[ii,jj]=sort(a,2,'descend')
v=ii(:,1:4)
idx=jj(:,1:4)
More Answers (1)
Guillaume
on 4 Dec 2014
Edited: Guillaume
on 4 Dec 2014
sort your matrix by column and in descending order. The first argument returned are the max, the second their indices:
A = [1 2 3 4 8 5 2 9 ; 5 6 4 7 9 1 1 2]
[maxvals, maxindices] = sort(A, 2, 'descend');
maxvals = maxvals(:, 1:4)
maxindices = maxindices(:, 1:4)
3 Comments
Guillaume
on 4 Dec 2014
Yes, I forgot the colon initially. However, I corrected that mistake before you made the comment.
My answer is identical to Azzi's except mine got some explanation (and useful variable names).
See Also
Categories
Find more on Logical 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!