Selecting required elements from a matrix
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I have a matrix A which contains 1's and 0's I wish to construct a new matrix B such that it has all the i,j values where A(i,j)=1, i.e B will be 2 X N matrix with its elements as the indices of the elements in matrix A who have a value of 1. for eg: A=[1,0,1,1,0] then B={[1,1];[1,3];[1,4]} Thanks
1 Comment
Matt J
on 15 Sep 2014
B={[1,1];[1,3];[1,4]} does not produce a 2xN matrix,
>> B={[1,1];[1,3];[1,4]}
B =
[1x2 double]
[1x2 double]
[1x2 double]
Accepted Answer
Guillaume
on 15 Sep 2014
Edited: Guillaume
on 15 Sep 2014
Is this what you're after ?
[row, col] = find(A);
B = [row col]';
I.e. use the two output version of find.
edit: The above answer assumes A is not a row vector. You can use Matt J fix to handle all cases or, if you know that A is a row vector:
[row, col] = find(A);
B = [row; col];
2 Comments
Guillaume
on 15 Sep 2014
Oh yes, thanks!
I really hate that you can't write simple generic code in matlab because the shape of the output is not always the same.
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