[R] Multiple merge, better solution?

[baptiste auguie]

Another option using Recall,


merge.rec <- function(.list, ...){
	if(length(.list)==1) return(.list[[1]])
	Recall(c(list(merge(.list[[1]], .list[[2]], ...)), .list[-(1:2)]), ...)
}

my.list <- list(DF1, DF2, DF3, DF4)
test2 <- merge.rec(my.list, by.x="var1", by.y="var1", all=T)

all.equal(test2, g)

Note that your second example does not work because in the last step  
there are no common names between g and DF4 (I think). Using  
suffixes=c("", "") seems to do the trick but I'm not sure it's giving  
the result you want/expect.

Hope this helps,

baptiste



On 19 Feb 2009, at 10:21, Lauri Nikkinen wrote:

> Hello,
>
> My problem is that I would like to merge multiple files with a common
> column but merge accepts only two
> data.frames to merge. In the real situation, I have 26 different
> data.frames with a common column. I can of course use merge many times
> (see below) but what would be more sophisticated solution? For loop?
> Any ideas?
>
> DF1 <- data.frame(var1 = letters[1:5], a = rnorm(5))
> DF2 <- data.frame(var1 = letters[3:7], b = rnorm(5))
> DF3 <- data.frame(var1 = letters[6:10], c = rnorm(5))
> DF4 <- data.frame(var1 = letters[8:12], d = rnorm(5))
>
> g <- merge(DF1, DF2, by.x="var1", by.y="var1", all=T)
> g <- merge(g, DF3, by.x="var1", by.y="var1", all=T)
> merge(g, DF4, by.x="var1", by.y="var1", all=T)
>
> Thanks in advance.
>
> -Lauri
>
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_____________________________

Baptiste Auguié

School of Physics
University of Exeter
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EX4 4QL, UK

Phone: +44 1392 264187

http://newton.ex.ac.uk/research/emag