Hi Ralf,

Perhaps the following is what you are looking for:

d <- data.frame(timestamp=c(3,3,3,5,8), mylabel=c("a","a","a","b","c"))
d
d[!duplicated(d$timestamp),]

HTH,
Jorge


On Fri, Jul 30, 2010 at 12:18 AM, Ralf B <> wrote:

> I have to deal with data frames that contain multiple entries of the
> same (based on an identifying collumn 'id'). The second collumn is
> mostly corresponding to the the id collumn which means that double
> entries can be eliminated with ?unique.
>
> a <- unique(data.frame(timestamp=c(3,3,3,5,8),
> mylabel=c("a","a","a","b","c")))
>
> However sometimes I have dataframes like this:
>
> a <- unique(data.frame(timestamp=c(3,3,3,5,8),
> mylabel=c("a","z","a","b","c")))
>
> which then results in:
>
>           timestamp mylabel
> 1         3       a
> 2         3       z
> 4         5       b
> 5         8       c
>
> However, I want only the first occurance of timestamp and then
> selected over the first label resulting in an output like this:
>
>           timestamp mylabel
> 1         3       a
> 4         5       b
> 5         8       c
>
> Is there something like groupBy (like in SQL) ?
>
> Best,
> Ralf
>
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