Ernesto Jardim wrote:
> Hi
>
> I want to combine 2 dataframes (t1 and t2) in order to get a third one
> (t3). The dataframes are below.
>
> In SQL I would do something like:
>
> SELECT t1.f1,t1.f2,t1.f3,t2.f4 FROM t1, t2
> WHERE t1.f1=t2.f1 AND t1.f2=t2.f2
>
> How can I do it with R ?
>
> Thanks
>
> EJ
>
> > t1
> f1 f2 f3
> 1 A C E1
> 2 A D E2
> 3 B C E3
> 4 B D E4
> > t2
> f1 f2 f4
> 1 A C F1
> 2 A C F2
> 3 B C F3
> 4 B C F4
> 5 A D F5
> 6 A D F6
> > t3
> f1 f2 f3 f4
> 1 A C E1 F1
> 2 A C E1 F2
> 3 B C E3 F3
> 4 B C E3 F4
> 5 A D E2 F5
> 6 A D E2 F6
>
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Try function "merge". For details see: help(merge)
> t1
[,1] [,2] [,3]
[1,] "A" "C" "E1"
[2,] "A" "D" "E2"
[3,] "B" "C" "E3"
[4,] "B" "D" "E4"
> t2
[,1] [,2] [,3]
[1,] "A" "C" "F1"
[2,] "A" "C" "F2"
[3,] "B" "C" "F3"
[4,] "B" "C" "F4"
[5,] "A" "D" "F5"
[6,] "A" "D" "F6"
> merge(t1,t2,1:2)
V1 V2 V3.x V3.y
1 A C E1 F1
2 A C E1 F2
3 A D E2 F5
4 A D E2 F6
5 B C E3 F3
6 B C E3 F4
--- Peter Wolf
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