[R] how to keep keep matching column in output of merge

[Nevil Amos]

Apologies,  it is there!

On 5/01/2011 1:26 AM, Sarah Goslee wrote:
> Hi Nevil,
>
> We really need an example here of what you're doing, since
> merge() does keep the id column by default.
>
>
>> x<- data.frame(id = c("a", "b", "c", NA), x=c(1,2,3,4))
>> y<- data.frame(id1 = c(NA, "a", "d", "c"), y=c(101, 102, 103, 104))
>> merge(x, y)
>    id x   y
> 1  a 1 102
> 2  b 2 101
> 3  c 3 104
> 4  d 4 103
>
> Sarah
>
> On Tue, Jan 4, 2011 at 8:31 AM, Nevil Amos<nevil.amos at gmail.com>  wrote:
>> How do I keep the linking column[s] in a merge()?
>>   I need to use the values again in a further merge.
>>
>> thanks
>>
>> Nevil Amos
>>