Can this be vectorized?
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Dear all,
I have two vectors A and B of respective sizes na and nb, with na>=nb. All elements in B are unique while the elements in A are not. But all elements in A are in B. I would like to create a mapping between A and B and one way to do that is as follows:
A=nan(na,1);
for ii=1:nb
A(A==B(ii))=ii;
end
This works well be becomes prohibitively expensive for large na. And so my question is whether there is a way of getting rid of the for loop and/or creating this mapping differently.
Thanks,
P.
1 个评论
Andrei Bobrov
2014-10-30
can so:
out = nan(na,1);
for ii=1:nb
out(A==B(ii))=ii;
end
采纳的回答
Andrei Bobrov
2014-10-30
编辑：Andrei Bobrov
2014-10-30
[lc,ii] = ismember(A,B);
A(lc) = ii(lc);
or with nan
out = ii;
out(~lc) = nan;
or jast (with zeros)
out = ii;
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