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# how to merge two matrices via one common column

Asked by Xin CUI on 23 Jun 2013

Hi there. My question is that I have two matrices, say, A and B, A have two columns, 1 and 2, B has two columns, 3 and 4. Columns 2 and 3 are actually same numbers, BUT with difference order. How can I merge them together? For example, column 2 of matrix A is [a b c d e f]' and column 3 of matrix B is [d c b a e f]'. All the letters are unique ones. Is there an easy way to merge A and B?

## 1 Comment

Matt J on 23 Jun 2013

It is confusing to call the columns of B "3 and 4" if B only has two columns.

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Answer by Andrei Bobrov on 23 Jun 2013
```[~,ii] = ismember(A(:,2),B(:,1));
out = [A, B(ii,2)];
```

## 1 Comment

Xin CUI on 23 Jun 2013

Thank you. Works very well.

Answer by Matt J on 23 Jun 2013
Edited by Matt J on 23 Jun 2013
```Anew=sortrows(A,2);
Bnew=sortrows(B,1);
```
```merged=[Anew,Bnew(:,2)];
```

## 1 Comment

Xin CUI on 23 Jun 2013

Works great. Thank you.