How to know all rows of which column in matrix has data?

Question

Hi 
I have a matrix, I want to know which rows of first column has data , and if first row has data I check the other columns to have a data.

m= 1 0  0 1
     0 1  1 0
     1 1  1 0
in this matrix, the first column has 2 data, first and third rows. At this time I see the other column in frist row and I get that third column has data, I compute Jaccard similarity for first and third rows