# How to find index of first 3 maximum number in matrix

27 views (last 30 days)
Moe on 5 Nov 2014
Answered: Aida Arman on 21 Nov 2018
I have the following function that n is the first 3 maximum value of matrix m:
m = [7;1;4;4;12;2;6;10;2];
temp = sort( m, 'descend' );
n = temp(1:3)
I need to know the index of matrix n, like:
p = [5;8;1]; % first max value in matrix m is 12 that it located in the fifth row

Orion on 5 Nov 2014
Edited: Orion on 5 Nov 2014
use the second output argument of sort
m = [7;1;4;4;12;2;6;10;2];
[temp,originalpos] = sort( m, 'descend' );
n = temp(1:3)
p=originalpos(1:3)
Amit Kumar on 21 Feb 2018
Edited: Amit Kumar on 21 Feb 2018
Great.. I just want to add a comment that if you have NaN in your matrix replace beforehand as m(isnan(m))=0 and then use, as:
m = [7;1;4;4;NaN;2;6;10;2];
m(isnan(m))=0
[temp,originalpos] = sort( m, 'descend' );
n = temp(1:3)
p=originalpos(1:3)

Aida Arman on 21 Nov 2018

MA on 5 Nov 2014
Edited: MA on 5 Nov 2014
m = [7;1;4;4;12;2;6;10;2];
temp = sort( m, 'descend' );
n = temp(1:3);
for i=1:9
if n(1)==m(i)
p1=i;
elseif n(2)==m(i)
p2=i;
elseif n(3)==m(i)
p3=i;
end
end
p=[p1 p2 p3]

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