[R] Sort problem in merge()

[Gabor Grothendieck]

On 3/6/06, Gregor Gorjanc <gregor.gorjanc at gmail.com> wrote:
>
> But I want to get out
>
> A NA
> A NA
> C 1
> C 1
> 0 NA
> 0 NA
>

That's what I get except for the rownames.  Be sure to
make the factor levels consistent.  I have renamed the data frames
tmp1a and tmp2a to distinguish them from the ones in your
post and have also reset the rownames to be the original
ones, as requested, so that the following is self contained
and should be reproducible:

> levs <- c(LETTERS[1:6], "0")
> tmp1a <- data.frame(col1 = factor(c("A", "A", "C", "C", "0", "0"), levs))
> tmp2a <- data.frame(col1 = factor(c("C", "D", "E", "F"), levs), col2 = 1:4)
>
> outa <- merge( cbind(tmp1a, seq = 1:nrow(tmp1a)), tmp2a, all.x = TRUE)
> outa <- outa[out$seq, -2]
> rownames(outa) <- rownames(tmp1a)
> outa
  col1 col2
1    0   NA
2    0   NA
3    A   NA
4    A   NA
5    C    1
6    C    1
>
> R.version.string # Windows XP
[1] "R version 2.2.1, 2005-12-20"

By the way, the main limitation with this approach is that the elements of
tmp2$col1 be unique so that the result has rows which correspond to those
of tmp1; however, that seems to be the case here.