[R] Find all duplicate records

[Uwe Ligges]

On 02.10.2011 16:05, Erik Svensson wrote:
> Hello,
> In a data frame I want to identify ALL duplicate IDs in the example to be
> able to examine "OS" and "time".
>
> (df<-data.frame(ID=c("userA", "userB", "userA", "userC"),
>    OS=c("Win","OSX","Win", "Win64"),
>    time=c("12:22","23:22","04:44","12:28")))
>
>       ID    OS  time
> 1 userA   Win 12:22
> 2 userB   OSX 23:22
> 3 userA   Win 04:44
> 4 userC Win64 12:28
>
> My desired output is that ALL records with the same IDs are found:
>
> userA   Win 12:22
> userA   Win 04:44

See ?split or ?subset

Uwe Ligges


>
> preferably by returning logical values (TRUE FALSE TRUE FALSE)
>
> Is there a simple way to do that?
>
> [-- With duplicated(df$ID) the output will be
> [1] FALSE FALSE  TRUE FALSE
> i.e. not all user A records are found
>
> With unique(df$ID)
> [1] userA userB userC
> Levels: userA userB userC
> i.e. one of each ID is found --]
>
> Erik Svensson
>
> --
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>
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