[R] aggregate: "sum" not meaningful for factors
Sundar Dorai-Raj
sundar.dorai-raj at pdf.com
Thu Jan 2 15:00:03 CET 2003
Tord,
Tord Snall wrote:
> Dear all,
> I try to summarise my data per category using aggregate, but for some
> reason I get the error message "sum" not meaningful for factors even though
> my vector is numeric. The data set is shown below.
>
> Could someone please give a hint.
>
> Thanks in advance!
>
> Sincerely,
> Tord
>
>
aggregate requires the first argument to be numeric if you're using sum
or mean. The way you had it, aggregate was trying to sum your
classification variable as well which is of class `factor'. Try the
following instead.
> aggregate(list(tallstubbyta = test$tallstubbyta,
list(ObjektID = test$ObjektID), sum)
Regards,
Sundar
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