How do I compare each element of a row matrix with each element of another row matrix in MATLAB?

Question

I have q = [3 4 5]; and w = [5 6 7];. I want to compare every element of q with w (i.e. 3 compared with 5, 6, and 7). If it matches any element in w (like how 5 is in both q and w) then both q and w share 5 as a common key. How can I compute all the common keys for q and w?

Answer 1

[Q W] = meshgrid(q, w)
% Q =
%      3     4     5
%      3     4     5
%      3     4     5
% W =
%      5     5     5
%      6     6     6
%      7     7     7
Q == W
% ans =
%      0     0     1
%      0     0     0
%      0     0     0

Answer 2

Check out ismember, and especially the second and third output argumements if you need more information about the matches.

Answer 3

Try

>> x = intersect(q,w)

x = 

    5

This function treats the input vectors as sets and returns the set intersection. I think this is what you wanted to know. Is there a match yes/no? if x is empty (numel(x)==0) there was no match.

Answer 4

q = [3 4 5];
w = [5 6 7];

%# @sellibitze
intersect(q,w)

%# @Loren
q( ismember(q,w) )

%# Me :)
q( any(bsxfun(@eq, q, w'),1) )