Does the following do what you want? The singletons()
function identifies the entries that appear only once
in a vector and we use its output to eliminate the singleton
entries.
> singletons <- function(x) !(duplicated(x) | duplicated(x,fromLast=TRUE))
> d <- data.frame(x=c(101, 102, 101, 105, 102, 101), y=1001:1006)
> d
x y
1 101 1001
2 102 1002
3 101 1003
4 105 1004
5 102 1005
6 101 1006
> d[!singletons(d$x), , drop=FALSE]
x y
1 101 1001
2 102 1002
3 101 1003
5 102 1005
6 101 1006
Bill Dunlap
Spotfire, TIBCO Software
wdunlap tibco.com
> -----Original Message-----
> From: r-help-boun...@r-project.org [mailto:r-help-boun...@r-project.org] On
> Behalf Of Ellen S.
> Sent: Friday, July 22, 2011 10:02 AM
> To: r-help@r-project.org
> Subject: [R] matched pairs
>
> Hi all,
>
> I am hoping to keep certain rows of my data set. These are rows whose value
> in column X is equal to the value in column X for another row. For example:
>
> 1 1
> 2 1
> 3 2
> 4 3
> 5 4
> 6 4
>
> >From this I would want the following:
>
> 1 1
> 2 1
> 5 4
> 6 4
>
> I am struggling with the for loop. Here is what I have currently:
>
> ## where to store values
> pairs.list <- data.frame(NA, nrow(data), ncol(data))
>
> ## iterating through data
> for (i in 1:nn){
>
> # check value with next value, store both
> if(data$X[i]==data$X[i+1]){
> pairs.list[i] <- data[i]
> pairs.list[1+1] <- data[i+1]
> }
>
> # if values are different, discard the first, keep the second
> else{
> data <- data[which(!data[i]),]
> }
> }
> }
>
>
> Any suggestions welcome. Thank you!
>
> E
>
> --
> View this message in context:
> http://r.789695.n4.nabble.com/matched-pairs-tp3687257p3687257.html
> Sent from the R help mailing list archive at Nabble.com.
>
> ______________________________________________
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> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
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