how to add zeros around a matrix?
17 views (last 30 days)
Show older comments
for example i have a matrix A = [1 2 3; 2 3 4; 5 6 7] I am working on image processing and I want to add zeros around this matrix like below. How can i do that?
0 0 0 0 0
0 1 2 3 0
0 2 3 4 0
0 5 6 7 0
0 0 0 0 0
0 Comments
Accepted Answer
Stephen23
on 22 Nov 2017
>> conv2(A,[0,0,0;0,1,0;0,0,0])
ans =
0 0 0 0 0
0 1 2 3 0
0 2 3 4 0
0 5 6 7 0
0 0 0 0 0
5 Comments
Stephen23
on 22 Nov 2017
Edited: Stephen23
on 22 Nov 2017
It is not clear what you would expect the result to be. MATLAB does not currently have a syntax for looping over two variables at once. You could define the loop to be an index and use that to select elements from those vectors:
iV = 0:1:5;
jV = 0:1:5;
for k = 1:numel(iV)
iN = iV(k);
jN = jV(k);
end
Eren Ozcelik
on 30 Apr 2021
Hi. How can I use this method for non-square matrix? For example creating a border for 1000x1500 matrix.
More Answers (3)
Andrei Bobrov
on 22 Nov 2017
Edited: Andrei Bobrov
on 22 Nov 2017
padarray(A,[1 1],0)
2 Comments
DGM
on 16 Jul 2022
While padarray() requires IPT, MIMT has padarrayFB(), which uses, but does not require IPT. That's a possibility for those who don't have IPT. ... but then MIMT also has other options for adding borders to images.
noam gridish
on 12 Mar 2024
% create bigger mat of zeros
[m,n]=size(A);
paded_mat=zeros(m+1,n+1);
paded_mat(2:end-1,2:end-1)=A;
A=paded_mat;
1 Comment
DGM
on 13 Mar 2024
Have you tested this? I ask because it will throw an error. Your preallocated array is too small.
See Also
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!