MATLAB Answers

0

Compare matrix element without loops

Asked by shdotcom shdotcom on 4 May 2019
Latest activity Commented on by dpb
on 4 May 2019
Accepted Answer by dpb
Hi,
Is there any way to get same result without using loops?
G = [5 8; 8 5; 3 9; 7 3; 1 4; 5 10; 6 7; 4 10; 4 7; 1 6];
n = 2;
nG = size(G,1);
for ii=1:nG
zz =1;
isDom = [];
for kk=1:n
for jj=1:nG
if ii ~= jj
isDom(zz) = G(ii,kk) < G(jj,kk);
zz = zz +1;
end
end
end
R(ii) = sum(isDom==1);
end

  0 Comments

Sign in to comment.

Products

1 Answers

Answer by dpb
on 4 May 2019
Edited by dpb
on 4 May 2019
 Accepted Answer

Not w/o zero loops, think not, but can reduce to one...
idx=1:nG; % working index array for element logical lookup/exclusion
R=zeros(nG,1); % preallocate
for i=1:nG
isDom=(G(i,:)-G(idx~=i,:));
R(i)=sum(isDom(:)<0);
end
You can eliminate the intermediate isDom temporary if desired..."exercise for the student" :)

  2 Comments

dpb
on 4 May 2019
You can also, of course, remove the explicit loop via arrayfun, but the loop is still there and resulting code is somewhat obfuscated and may well be slower, besides...

Sign in to comment.



Translated by