MATLAB: How to use FIND to extract the indices of 1 elements in a 0/1 matrix

Question

I only have some 0/1 matrices and they are generated randomly. How can I define X like this: (please see Matrix image)

The first index of X shows it's in the r-th(r=1) row, the second index shows it's the n-th 1 in that section in that row, and the third index shows it's in the s-th section of that row, and the value of X=K means that it’s the K-th element of that whole row (counting elements from the beginning of that row up to that 1). Here r=1:4 n=1:5 s=1:2

Answer 1

[row,col] = find(X) returns the row and column subscripts of each nonzero element in array X

PS: matlab indexes are starting from 1, not from 0