How to find positive values in 1500 matrices(720*1280)?

I've got a data like this. Each file contains zero and some positive values or all zeros.

I want to find which matrix contains positive values.

Answer 1

[Matt J]

If C is your cell array

find(cellfun(@nnz,C))

Answer 2

[KSSV]

If A is your matrix.

idx = A>0 ;    % this gives indices of posittive values
idx = sign(A)  % this gives sign of values in A
A(A>0)    % this gives values in A which are greater than 0

[Wenyi Xiao]

I want to keep n matrices that contains positive integers.

so there will be n*1 cell. Each contains 720*1280.

Do you know how?