How to multiply values to specific elements in a matrix?
16 views (last 30 days)
Show older comments
I have a matrix
A=[ 1 0 0 0;
0 1 0 0;
1 0 0 0;
0 0 0 1 ]
I want to multiply an array B= [1,5,7,8] to wherever 1's are in matrix A. Resultant matrix is:
A = [1 0 0 0;
0 5 0 0 ;
7 0 0 0;
0 0 0 8]
How can I do it in vectorized form? Please note that number of ones in input matrix A will always equal the length of array B
Thanks!
0 Comments
Answers (2)
the cyclist
on 19 Nov 2016
Edited: the cyclist
on 19 Nov 2016
In MATLAB 2016b (and presumably later yet-to-be-released versions), you can just write
A.*B'
In earlier versions, you need to use bsxfun:
bsxfun(@times,A,B')
0 Comments
Roger Stafford
on 20 Nov 2016
Assuming the number of ones in A is equal to the length of B,
At = A.’;
At(At==1) = B;
A = At.’;
0 Comments
See Also
Categories
Find more on Matrix Indexing in Help Center and File Exchange
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!