MATLAB: Find a row in a matrix

findindexingmatrix arraymatrix manipulation

Hi!
I have a generic matrix with random numbers (-1 and +1).
M=[ 1 -1  1 -1
    1  1  1 -1
   -1  1 -1  1 % <----- this row
    1  1 -1  1];
How can I extract a row index?
a=[-1  1 -1  1];
idx=3;
Thank you

Best Answer

Assuming you have that vector already:
M=[ 1 -1  1 -1
    1  1  1 -1
   -1  1 -1  1 % <----- this row
    1  1 -1  1];
a=[-1  1 -1  1];
tmp=abs(M-a);%uses implicit expansion, works in R2016b and newer
tmp=sum(tmp,2) <= eps;
idx=find(tmp);
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