Azzera filtri
Azzera filtri

Finding element with max value in each row of a matrix

1 visualizzazione (ultimi 30 giorni)
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!

Risposta accettata

Azzi Abdelmalek
Azzi Abdelmalek il 4 Dic 2014
Modificato: Azzi Abdelmalek il 4 Dic 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)

Più risposte (1)

Guillaume
Guillaume il 4 Dic 2014
Modificato: Guillaume il 4 Dic 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 Commenti
Guillaume
Guillaume il 4 Dic 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).
Konstantinos
Konstantinos il 4 Dic 2014
You are correct! thanks for your help!

Accedi per commentare.

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by