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Need to match Data

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Johannes
Johannes 2012-10-8
Hello,
I like to match the entries in column 2 of matrix A to the reference numbers of B. I'm going to do that for large data sets. Code like follows does exactly what I want but will be to slow. Is there an intelligent function/way available to do that? Thanks a lot!
A = [2 3 5 7; 23 54 76 86]';
B = [1:7]';
j=1;
for i = 1:7
if B(i,1) == A(j,1)
B(i,2) = A(j,2);
j = j+1;
end
end
result: B =
1 0
2 23
3 54
4 0
5 76
6 0
7 86

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采纳的回答

Matt Fig
Matt Fig 2012-10-8
B(A(:,1),2) = A(:,2)
  2 个评论
Matt Fig
Matt Fig 2012-10-8
Johannes comments:
"Thank you. That was a bad example, my mistake.
What would be the solution for vectors like that:
A = [7 3 5 9; 23 54 76 86]';
B = [3:15]';"
Matt Fig
Matt Fig 2012-10-8
编辑：Matt Fig 2012-10-8
In that case:
A = [7 3 5 9; 23 54 76 86]';
B = [3:15]';
As = sortrows(A,1);
idx = ismember(B,As(:,1));
B(idx,2) = As(:,2)

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更多回答（2 个）

Andrei Bobrov
Andrei Bobrov 2012-10-8
编辑：Andrei Bobrov 2012-10-8
A = [7 3 5 9; 23 54 76 86]';
B = [3:15]';
[a,b] = ismember(B,A(:,1));
B(a,2) = A(b(a),2);
Johannes
Johannes 2012-10-9
thank you all! My final solution is the following:
B(ismember(A),2)=A(ismember(A,B),2);
Works perfect and very fast.
Thank you again for your help.
Best, Johannes

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