Hi Juliane,
Try TripsData[, 2:3] instead of TripsData[ 2:3 ] in the aggregate call.

HTH,
Jorge


On Thu, Sep 24, 2009 at 6:52 AM, Juliane Struve <> wrote:

> Dear list,
>
> would anybody be able to tell me why the statement
>
> Tripstatistics=aggregate(TripsData[2:3],by=list(Trip=Tripmatch),FUN="mean")
>
> seems to work well with TripsData 1 but not with TripsData 2 ?
>
> With TripsData 2 it yields
>
> Error in FUN(X[[1L]], ...) : arguments must have same length
>
> I can't see a difference in the two data sets. Could someone shed light on
> the error message ? Maybe that would help me figure out where the problem
> is.
>
> Thanks very much for any help.
>
> Juliane
>
> PS: The examples below contain the  first 5 rows  of my two datafiles.
>
>
> TripsData 1
>
>            Trip Distance TimeDiff Tripmatch
> 7329 35,36 172.7453   0.0041     35,36
> 7371 36,35 172.7453   0.0004     35,36
> 7372 35,36 172.7453   0.0000     35,36
> 7373 36,35 172.7453   0.0004     35,36
> 7374 35,36 172.7453   0.0001     35,36
>
>
> TripsData 2
>
>             Trip Distance TimeDiff Tripmatch
> 1617 19,20 1087.365   0.0441     19,20
> 1899 20,19 1087.365   0.0207     19,20
> 1915 19,20 1087.365   0.0361     19,20
> 3285 20,19 1087.365   0.0356     19,20
> 3826 19,20 1087.365   0.0697     19,20
>
>
>
>
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