[R] a merge() problem

[Peter Ehlers]

On 2012-10-07 08:34, Sam Steingold wrote:
> I know it does not look very good - using the same column names to mean
> different things in different data frames, but here you go:
> --8<---------------cut here---------------start------------->8---
>> x <- data.frame(a=c(1,2,3),b=c(4,5,6))
>> y <- data.frame(b=c(1,2),a=c("a","b"))
>> merge(x,y,by.x="a",by.y="b",all.x=TRUE,suffixes=c("","y"))
>    a b    a
> 1 1 4    a
> 2 2 5    b
> 3 3 6 <NA>
> Warning message:
> In merge.data.frame(x, y, by.x = "a", by.y = "b", all.x = TRUE) :
>    column name 'a' is duplicated in the result
> --8<---------------cut here---------------end--------------->8---
> why is the suffixes argument ignored?
> I mean, I expected that the second "a" to be "a.y".

The 'suffixes' argument refers to _non-by_ names only (as per ?merge).

Peter Ehlers

> (when I omit suffixes, the result is the same).
> Thanks.
>