On 10 Jan 2003 at 15:19, Tord Snall wrote:
> Dear all,
>
> I would be really happy for help with the following because I will treat
> many columns the same way.
>
> nlevels per ObjektID is what I want, but nlevels returns all levels
> occurring in cpy.busk$TradArt:
>
> buskartant<- aggregate(list(trash = cpy.busk$TradArt), list(ObjektID
> cpy.busk$ObjektID), nlevels)
>
> But as you can see I use it below anyway. I could use any function instaed
> of nlevels beacuse now I just want the ObjektID in the right order.
>
> Greg Warnes kindly helped me with this solution:
> group.list <- split(cpy.busk$TradArt, cpy.busk$ObjektID)
> buskartant$buskartant <- sapply( group.list, function(x)
length(unique(x)) )
>
> But the probelm is that unique considers NA as a category, and there is no
> na.rm argument in unique().
What about wrapping unique in na.omit:
na.omit(unique(x))
Kjetil Halvorsen
>
> Please give a hint.
>
> Thanks a lot in advance!
>
> Sincerely,
> Tord
>
> -----------------------------------------------------------------------
> Tord Sn?ll
> Avd. f v?xtekologi, Evolutionsbiologiskt centrum, Uppsala universitet
> Dept. of Plant Ecology, Evolutionary Biology Centre, Uppsala University
> Villav?gen 14
> SE-752 36 Uppsala, Sweden
> Tel: 018-471 28 82 (int +46 18 471 28 82) (work)
> Tel: 018-25 71 33 (int +46 18 25 71 33) (home)
> Fax: 018-55 34 19 (int +46 18 55 34 19) (work)
> E-mail: Tord.Snall at ebc.uu.se
> Check this: http://www.vaxtbio.uu.se/resfold/snall.htm!
> ------------------------------------------------------------------------
>
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