MATLAB: How to quickly find the first non-zero element without iterations in all columns in a sparse matrix

Question

Hi, All,

I have a big sparse matrix A. I want to find out the first non-zero element in all columns from the top. Here is my code:

reorderCol = [];

for jCol = 1 : length(A(1,:))

eee = find(A(:,jCol),1,'first');

reorderCol = [reorderCol eee];

end

For example, I have matrix A = [0 0 0;0 5 0;0 0 1;0 0 0;-1 0 -4]. My code gives the following result:

reorderCol = [5 2 3];

I am wondering if it is possible to obtain reorderCol without iterations. Thanks a lot.

Benson

Answer 1

[~,result]=max(logical(A),[],1);