MATLAB Answers

0

concatenate arrays after performing addition

Asked by Neil Barker on 15 Oct 2019
Latest activity Answered by Jos (10584)
on 15 Oct 2019
I'm trying to add all the elements of A with element 1 of B. then do it again with element 2 etc. I'd like to concatinate the four 3x3 arrays into one array D (3x12). But i'm getting error messages.
This test code does what i want with array C, but i'm struggling getting all the previous FOR loops of C and the concatenation
A = [1,2,3;4,5,6;7,8,9];
B = [2,3,4,5];
C = zeros(3);
D = zeros(3,12);
for i = 1:numel(B)
C = A + B(i)
end
Thanks for any assistance you give,
Neil

  0 Comments

Sign in to comment.

Products

2 Answers

Answer by Andrei Bobrov
on 15 Oct 2019
 Accepted Answer

A = [1,2,3;4,5,6;7,8,9];
B = [2,3,4,5];
D = reshape(permute(A + reshape(B,1,1,[]),[2,1,3]),size(A,2),[])';

  1 Comment

Thanks for your answer Andrei. I'll go through it now. My actual code will be A = NxN and
B = 1xN. so hopefully i'll be able to make a general case for D.
thanks again,
Neil

Sign in to comment.


Answer by Jos (10584)
on 15 Oct 2019

A little simpler than all those permutes and reshapes:
A = [1 2 3 ; 4 5 6 ; 7 8 9] ;
B = [2 3 4 5] ;
C = repmat(A, numel(B), 1) + repelem(B(:), size(A,1), size(A,2))

  0 Comments

Sign in to comment.