How to find number and position from cell

I have a large cell file (1.6*10^6 rows) with only ones and []. I want to find the positions of the ones, preferably converted to ones and zeros. Since it's a large file, I would rather not do it in a loop.

Example:

a = [1 1 [] [] 1]

have ones in position 1,2,5

[Jan]

A cell requires curly braces, because [1 1 [] [] 1] is the same as [1,1,1].

Answer 1

[Jan]

a = {1, 1, [], [], 1};
index = find(~cellfun('isempty', a));

Perhaps this is slightly faster:

index = find(cellfun('prodofsize', a));

While this is slower:

index = find(cellfun(@(c) isequal(c, 1), a));

[Philip]

Thank a lot, this worked out fine!