Clear Filters
Clear Filters

How to set all elements in a 2D Matrix between two indices to "1" in each row

5 views (last 30 days)
I've a matrix A e.g. like this:
A =
1 0 0 1 0 0
0 0 1 0 0 1
0 1 1 0 0 0
0 1 0 1 0 0
And I want all elements between the "ones" per row to be "one" as well. The result should look like this: B =
1 1 1 1 0 0
0 0 1 1 1 1
0 1 1 0 0 0
0 1 1 1 0 0
If it helps, I also have two vectors with the indices of the first and second one.
Thanks!!
PS: If possible the solution would not use any loops since the real matrix that I have to use is very large and the program shall be very efficient.

Accepted Answer

Alfonso Nieto-Castanon
Alfonso Nieto-Castanon on 5 Dec 2013
cumsum(A,2)==1|A;

More Answers (2)

Andrei Bobrov
Andrei Bobrov on 5 Dec 2013
cumsum(A,2)>0 & fliplr(cumsum(A(:,end:-1:1),2))>0

sixwwwwww
sixwwwwww on 5 Dec 2013
you can do it as follow:
for i = 1:size(A, 1)
idx = find(A(i, :));
A(i, min(idx):max(idx)) = 1;
end
  1 Comment
Tim
Tim on 5 Dec 2013
Nice, thanks! That helps. But is there a way to avoid the loop? E.g. use a vector that contains all the "idx" or so? Thanks!

Sign in to comment.

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!