[R] merging with aggregating

[Dubravko Dolic]

Dear List,

I have two data.frame of the following form:

A:

n  V1 V2
1  12  0 
2  10  8
3   3  8 
4   8  4
6   7  3  
7  12  0 
8   1  0 
9  18  0 
10  1  0
13  2  0

B:

n  V1 V2
1   0  2
2   0  3
3   1  9
4  12  8 
5   2  9
6   2  9
8   2  0
10  4  1
11  7  1
12  0  1


Now I want to merge those frame to one data.frame with summing up the
columns V1 and V2 but not the column n. So the result in this example
would be:

AB:

n  V1 V2
1  12  2
2  10 11 
3   4 17
4  20 12
5   2  9
6   9 12
7  12  0
8   3  0
9  18  0
10  5  1
11  7  1
12  0  1
13  2  0 


So Columns V1 and V2 are the sum of A und B while n has its old value.
Notice that there are different rows in n of A and B.

I don't have a clue how to start here. Any hint is welcome.

Thanks

Dubravko Dolic
Munich
Germany