How to compare rows in a matrix

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Sameer
Sameer on 18 Jul 2014
Commented: Sameer on 18 Jul 2014
Hello all
I have a matrix A
A =
1 1 0 0 0
0 -1 0 1 0
-1 0 1 1 0
lets say I am looking at the second row in which column 2 and 4 have value present now if I compare it with the row above which has values in the column 1 and column 2 so I want to know the column number which has values in both the rows, I mean here the column number 2 should be returned. Similarly row 3 should be compared with row 1 and 2 and for each row a column number should be returned.
Can anyone please guide me through this.
Regards
  1 Comment
Azzi Abdelmalek
Azzi Abdelmalek on 18 Jul 2014
Edited: Azzi Abdelmalek on 18 Jul 2014
What is the expected result for your example?

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Accepted Answer

Azzi Abdelmalek
Azzi Abdelmalek on 18 Jul 2014
Comparison between row 1 and row 2
A =[ 1 1 0 0 0
0 -1 0 1 0
-1 0 1 1 0]
idx=find(all(A(1:2,:)))
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More Answers (1)

the cyclist
the cyclist on 18 Jul 2014
I think that
[rows,cols] = find(A(2:end,:)~=0 & A(1:end-1,:)~=0)
does what you want.
rows will be the index to the "top" row being compared, and "cols" will be the column numbers that meet your criterion.
For example, in your case
rows = [1; 2];
and
cols = [2; 4];
cols seems to be the main thing you are going for.
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