[R] dataframes (The message that once had a suspicious header)

[Peter Wolf]

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
>
> ______________________________________________
> R-help at stat.math.ethz.ch mailing list
> https://www.stat.math.ethz.ch/mailman/listinfo/r-help

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