non-looping way to compare cellstr arrays of different sizes

2011 8 24
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Suppose A = {'aa', 'kk', 'ccc'}, B = {'aa', 'bb', 'cc', 'dd', 'ee'}.
Is there a not-explicitly-looping way to return a logical array the same size as A that is 1 where an element of A is in B, 0 where it is not, e.g.,
"whereMember"(A,B) => [1 0 0]?
Thanks!

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Oleg Komarov
Oleg Komarov 2011-8-24

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A = {'aa', 'kk', 'ccc'};
B = {'aa', 'bb', 'cc', 'dd', 'ee'};
ismember(A,B)

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David Goldsmith
David Goldsmith 2011-8-24
DOH! (I've gotten so used to using ismember when the first argument is a scalar I forgot that it could be an array!) :-(
Thanks!
Oh, but wait a sec, I forgot: I'd also like it to be case insensitive, i.e., A = {'Aa', 'kk', 'cc'} would also return [1 0 0]. Sorry!
DG
David Goldsmith
David Goldsmith 2011-8-24
DOH! again. (But shouldn't that be ismember(lower(A),lower(B)) - I want it to be "commutatively" case insensitive.) :-)
Thanks one more time!

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David Goldsmith
David Goldsmith 2011-8-24

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Here's a little function that does if the answer to the revised question is "no":
function la = cellstrIsMember(A, B, i)
% la = 1 where the elements of cellstr array A are in cellstr array B, 0 where they are not
% i is an optional parameter: if case matters, i=1 (the default),
% 0 for case-insensitive matching (which is slower)
%
% Author: David Goldsmith, Wash. State Dept. of Ecology, dgol461@ecy.wa.gov
% Release date: 2011-08-24
if nargin < 3
i = 1;
end
if i || isempty(A) || isempty(B)
la = ismember(A, B);
else
la = zeros(size(A));
for i=1:length(A)
if any(strcmpi(A{i}, B))
la(i) = 1;
end
end
end
end

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Jan
Jan 2011-8-24
Small suggestions: Using "numel(A)" instead of "length(A)" considers cell arrays of any dimensions.
"la=false(size(A))" replies a logical array as ISMEMBER. Then the loop can be:
for i=1:numel(A), la(i)= any(strcmpi(A{i}, B)); end
BTW.: Your loop is faster than ISMEMBER.
Jan
Jan 2011-8-24
What is the meaning of your otehr thread: http://www.mathworks.com/matlabcentral/answers/13906-indexing-way-to-look-for-specifc-cell-arrays-in-a-cell-array-of-cell-arrays ???
David Goldsmith
David Goldsmith 2011-8-24
Oh, and thanks for the refactoring--very interesting that it's faster; I guess ismember must come w/ a lot more overhead?
David Goldsmith
David Goldsmith 2011-8-25
Jan: may I credit you in my by-line comment? If yes, what is your affiliation, if any?
Jan
Jan 2011-8-25
@David: I've tried to let leo.org tell me, what affiliation is. Leo meant, that either somebody adopts me, or that it concerns my fatherhood. :-) If this means my company: I'm a freelancer. Perhaps my FEX author ID 15233 is helpful?

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