# how to do loop on rows matrix?

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Risma Fitriyani on 23 Dec 2022
Commented: Image Analyst on 27 Dec 2022
i have zeros matrix which has 3 rows and 6 columns. i want to allocate “1” on zeros matrix for each columns in order to get the result output like this attached picture. can anyone be kind to help me? thanks in advance
Risma Fitriyani on 23 Dec 2022

VBBV on 23 Dec 2022
Edited: VBBV on 23 Dec 2022
As mentioned in your question, if you have zeros matrix to start with and want to allocate 1s to specfiic zero locations, then you can get the matrix in snapshot using loop as below
A = zeros(3,6); % assume A as your zeros matrix
for k = 1:length(A)-2
if k == 1 | k == 2 | k == 3
A(k,k) = 1;
elseif k == 4
A(1,k) = 1;
A(2,k+1) = 1;
A(3,k+2) = 1;
end
end
A
A = 3×6
1 0 0 1 0 0 0 1 0 0 1 0 0 0 1 0 0 1
##### 2 CommentsShowHide 1 older comment
VBBV on 23 Dec 2022
It depends on how you want final matrix to look like. That is "in which specific positions you want to allocate 1s in zero matrix"

Markus M. on 23 Dec 2022
Edited: Markus M. on 23 Dec 2022
It looks like the 1's are only needed on the diagonal elements.
You can do this with:
repmat(eye(3),1,2)
Risma Fitriyani on 26 Dec 2022
this is worked! thank you so much, this helped me a lot.

Image Analyst on 26 Dec 2022
Instead of a for loop, you can use the toeplitz function:
% For 3x6:
c = [1 0 0 1 0 0];
r = [1 0 0];
output = toeplitz(r, c)
output = 3×6
1 0 0 1 0 0 0 1 0 0 1 0 0 0 1 0 0 1
% For 15 by 25
c = [1 0 0 1 0 0 1 0 0 1 0 0 1 0 0 1 0 0 1 0 0 1 0 0 1];
r = [1; zeros(15, 1)];
output = toeplitz(r, c)
output = 16×25
1 0 0 1 0 0 1 0 0 1 0 0 1 0 0 1 0 0 1 0 0 1 0 0 1 0 1 0 0 1 0 0 1 0 0 1 0 0 1 0 0 1 0 0 1 0 0 1 0 0 0 0 1 0 0 1 0 0 1 0 0 1 0 0 1 0 0 1 0 0 1 0 0 1 0 0 0 0 1 0 0 1 0 0 1 0 0 1 0 0 1 0 0 1 0 0 1 0 0 1 0 0 0 0 1 0 0 1 0 0 1 0 0 1 0 0 1 0 0 1 0 0 1 0 0 0 0 0 0 0 1 0 0 1 0 0 1 0 0 1 0 0 1 0 0 1 0 0 1 0 0 0 0 0 0 0 1 0 0 1 0 0 1 0 0 1 0 0 1 0 0 1 0 0 1 0 0 0 0 0 0 0 1 0 0 1 0 0 1 0 0 1 0 0 1 0 0 1 0 0 0 0 0 0 0 0 0 0 1 0 0 1 0 0 1 0 0 1 0 0 1 0 0 1 0 0 0 0 0 0 0 0 0 0 1 0 0 1 0 0 1 0 0 1 0 0 1 0 0 1
Image Analyst on 27 Dec 2022
@Risma Fitriyani did you not like my answer for the 15x25? Does the answer you accepted work?
Again, can you give the full output for your 15x25 matrix like @Markus M. directly asked you for? I'd like to see how my solution does not do what you want.

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