how to add zeros around a matrix?
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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
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Stephen23
2017년 11월 22일
>> 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
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Stephen23
2017년 11월 22일
편집: Stephen23
2017년 11월 22일
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
2021년 4월 30일
Hi. How can I use this method for non-square matrix? For example creating a border for 1000x1500 matrix.
추가 답변 (3개)
Andrei Bobrov
2017년 11월 22일
편집: Andrei Bobrov
2017년 11월 22일
padarray(A,[1 1],0)
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DGM
2022년 7월 16일
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
2024년 3월 12일
% 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;
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DGM
2024년 3월 13일
Have you tested this? I ask because it will throw an error. Your preallocated array is too small.
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