Replacing Values of a Larger Matrix with that of a Smaller Matrix

Question

Richard Zareck 2017-9-10

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https://ww2.mathworks.cn/matlabcentral/answers/355894-replacing-values-of-a-larger-matrix-with-that-of-a-smaller-matrix

回答： Jose Marques 2017-9-10

I have a matrix A that looks like:

1 1 1 1 1 1 1 1 1                                                           
1 1 1 1 1 1 1 1 1
1 1 1 1 1 1 1 1 1
1 1 1 1 1 1 1 1 1
1 1 1 1 1 1 1 1 1
1 1 1 1 1 1 1 1 1

and a matrix B that looks like:

How can I create a new matrix C that looks like:

0 1 1 0 0 1 1 0 0                                                           
0 1 1 0 0 1 1 0 0
0 1 1 0 0 1 1 0 0
0 1 1 0 0 1 1 0 0
0 1 1 0 0 1 1 0 0
0 1 1 0 0 1 1 0 0

by inserting B into A and without using loops. Also if this is not possible, is there a way to create matrix C from matrix A?

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Answer 1

Cedric 2017-9-10

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https://ww2.mathworks.cn/matlabcentral/answers/355894-replacing-values-of-a-larger-matrix-with-that-of-a-smaller-matrix#answer_280942

编辑：Cedric 2017-9-10

在 MATLAB Online 中打开

 b = mod( floor( (0:size( A, 2 )-1)/2 ), 2 ) ;
 C = bsxfun( @times, A, b ) ;

Note that the way I define b=00110011.. is ... shows that I am tired!

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Richard Zareck 2017-9-10

Thank you!!

Cedric 2017-9-10

My pleasure. I answered thinking that you wanted to "mask" columns of A, hence the multiplication by 0 and 1 of given columns. Let me know if the purpose was different.

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Answer 2

Jose Marques 2017-9-10

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https://ww2.mathworks.cn/matlabcentral/answers/355894-replacing-values-of-a-larger-matrix-with-that-of-a-smaller-matrix#answer_280943

在 MATLAB Online 中打开

imgSiz = [x1,y1];
blkSiz = [x1,size_column];
numRep = imgSiz./blkSiz;
basMat = toeplitz(mod(0:numRep(1)-1,2),mod(0:numRep(2)-1,2));
mask(:,:) = repelem(basMat,x1,size_column);