Actually, think I figured out an answer. I can just use repmat to create a matrix of n copies of the vector, and use == with the vector to compare it that way.
Produce equality matrix based on elements in vector.
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Given two equally sized vectors A and B, is there any way to make a matrix C of 1's and zero's such that the kth row of C contains 1's wherever elements of B equal the kth element of A?
I can do it by looping through elements of A, but I want to know if there's a vectorised way of doing this to speed it up?
"I can just use repmat"
You don't need repmat. Implicit expansion will take care of repeating the elements for you and will be faster. See my answer.
%assuming A and B are both row vectors:
C = A.' == B;
If they're both column vectors, transpose B instead.
More Answers (3)
Fangjun Jiang on 27 Mar 2020
Bernd Wagner on 27 Mar 2020
Does the Logical opperator C= A==B not do that work?
It compares values in Vector A and responds a logical value 1 if the Value is also on the same line in B. Hence your C vector will be a vector of 0 and 1 with 1 if A==B.
darova on 27 Mar 2020
% make all combinations using bsxfun
C = bsxfun(@minus,b(:),a(:)'); % b - rows, a - columns
[i,j] = find(~C); % find 'zero'
C1 = C*0;
C1(i,:) = 1; % make entire row '1' if any element a==b
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