[R] merging data.frames of different length

[Martin Batholdy]

hi,


I have two data.frames each with two columns;


x1

1	4
1	3
1	6
2	9
2	2
2	5
3	6
3	7
3	4


x2

1	-3
1	-7
2	-3
2	-2
2	-8
3	-1
3	-2
3	-1

now I want to merge this data.frames to one data.frame.

The problem is, that sometimes there is a different number of elements  
per category.
(like above x1 has 3 values for the value 1 in the first row, but x2  
has only 2 values for the value 1 in the first row).

Is there an easy way to merge this two data.frames by deleting the  
rows that only one data.frame "has".
In the example, that resulting data.frame would be the data.frame x1  
and x2 except the row 3 of data.frame x1.

thanks for any suggestions!