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find rows of two matricies (of different sizes) based on matching element of one column

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Adam
Adam 2015-11-10
评论： Adam 2015-11-10
Given two matrices A[1000x4] and B[500x4] what is the fastest way in MATLAB to extract the complete rows of A which share the same element values in column 4 as B does?
for example if,
A=[1 2 3 7;
2 6 9 1;
8 3 4 8] and
B=[9 2 5 1;
6 2 1 5;
3 6 6 8].
What is the most efficient way to create a new array
C=[2 6 9 1;
8 3 4 8],
having the rows of A with same element in column 4 as B does?
Thanks!

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采纳的回答

Image Analyst
Image Analyst 2015-11-10
Try ismember():
A=[1 2 3 7;
2 6 9 1;
8 3 4 8]
B=[9 2 5 1;
6 2 1 5;
3 6 6 8]
[ia, ib] = ismember(A(:,4), B(:, 4))
C = A(find(ib),:)

更多回答（1 个）

James Tursa
James Tursa 2015-11-10
Caution, untested:
k = ismember(A(:,4),B(:,4));
C = A(k,:);

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