Constraints applied to circshift function

If i have a matrix A:

0 0
0 1
1 1
1 1
0 0

and I applied the following shift function (to shift rows downwards):

id=randi(6,1,size(A,2));
shift = cell2mat(arrayfun(@(x) circshift(A(:,x),[id(x) 1]),(1:numel(id)),'un',0));

How would I apply the following constraint: "The ones never get separated in their respective column" such as in the below eg. with column 2

id = 1 2

A=
0 1
0 0
0 0
1 1
1 1

Thank you for any help!

Answer 1

[Image Analyst]

You can use all() or sum() to find out which rows are all zeros. Then use find() to figure out where the last row that has a 1 in it. Then you'll know how far you can shift the rows down. If you pick a random shift, make sure that it's not more than that number or else they'll go past the end of the array.

Here's a start for you:

theSum = sum(A, 2);
lastRow = find(theSum > 0, 1, 'last');
rowsThatICanShift = size(A, 1) - lastRow;