如何找到具有至少一个非零元素的列的索引？

Question

Given a binary matrix in Matlab, I would like to find the index of the columns that have at least one non-zero element. How can I do this?

B
     1     1     0     0     0
     0     0     0     1     0
     0     1     0     0     0
     0     0     0     0     0

Answer 1

You can use any and find to find the indices of the columns:

indices = find(any(B,1))

Use any(B,1) to find the columns with at least one non-zero element, then use find to obtain the indices of these columns.