Dear Peter,
   
  I tryed something like 
   
  >head(especies.aicc)
         especie     aicc
1 Attila.rufus 17.15934
2 Attila.rufus 11.41371
3 Attila.rufus 11.41371
4 Attila.rufus 19.55998
5 Attila.rufus 17.23780
6 Attila.rufus 19.22545
   
  > especies.min<-aggregate.data.frame(especies.aicc,list
             (Especie=especies.aicc$especie),max)
   
  But it works fine only for "mean" FUN and not for "min" and "max". Also also, when I use "mean" I got the following warnings:
   
  > especies.min<-aggregate.data.frame(especies.aicc,list 
         (Especie=especies.aicc$especie),mean)

  Warning messages:
1: argument is not numeric or logical: returning NA in: mean.default(X[[1]], ...) 
2: argument is not numeric or logical: returning NA in: mean.default(X[[2]], ...) 
   
  In fact I need only min() and max().
   
  Miltinho
  -----------------

Peter Dalgaard <P.Dalgaard@biostat.ku.dk> escreveu:
  Milton Cezar Ribeiro wrote:
> Hi R-friends
> 
> I don´t know why the "min()" function below return the min value as factor. When i force the aicc.min using a as.numeric() function, it return a factor index (1,2,..) and not min value as I want. By the way, I included a sessionInfo() at the end of this e-mail.
> 
min() is not doing anything out of the ordinary, but cbind'ing it with
the character vector sp coerces it to character and rbind'ing to a data
frame turns character vectors into factors...

The whole thing looks like it could be a straightforward application of
aggregate().
> 
> In fact I had the same problem (values as factor) on other part of my script and I noticed that it occour when I use "cbind()". It is real?
> 
> Any idea? 
> 
> Kind regards,
> 
> Miltinho
> 
> > especies.aicc.min<-data.frame()
> 
>> for (sp in levels(especies.aicc$especie)) 
>> 
> + {
> + sele<-subset(especies.aicc,especie==sp)
> + especies.aicc.min<-rbind(especies.aicc.min,cbind(sp,aicc.min=min(sele$aicc)))
> + }
> 
>> especies.aicc.min
>> 
> sp aicc.min
> 1 Attila.rufus 6.7387056413613
> 2 Automolus.leucophthalmus 125.791300522824
> 
>> class(especies.aicc.min$aicc.min)
>> 
> [1] "factor"
> 
> -----------
> > sessionInfo()
> R version 2.4.0 (2006-10-03) 
> i386-pc-mingw32 
> locale:
> LC_COLLATE=English_Jamaica.1252;LC_CTYPE=English_Jamaica.1252;LC_MONETARY=English_Jamaica.1252;LC_NUMERIC=C;LC_TIME=English_Jamaica.1252
> attached base packages:
> [1] "methods" "stats" "graphics" "grDevices" "utils" "datasets" "base" 
> 
>
> 


-- 
O__ ---- Peter Dalgaard Øster Farimagsgade 5, Entr.B
c/ /'_ --- Dept. of Biostatistics PO Box 2099, 1014 Cph. K
(*) \(*) -- University of Copenhagen Denmark Ph: (+45) 35327918
~~~~~~~~~~ - (p.dalgaard@biostat.ku.dk) FAX: (+45) 35327907




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