[R] subset problem (reducing from six to two levels)

[Ine]

Great, this worked for me, exactly how I needed it.
Thanks for all the replies!


Peter Dalgaard wrote:
> 
> Ine wrote:
>> Hi all,
>> I have got a seemingly simple problem (I am an R starter) with subsetting
>> my
>> data set, but cannot figure out the solution: I want to subset a data set
>> from six to two levels, so that all analyses are done only with these two
>> remaining levels.
>> I tried
>> 
>> TOTAL<-read.delim('total.csv',header=T)
>> SUBSET.OF.TOTAL<-subset(TOTAL, FactorX %in% c("Level1","Level2"))
>> attach(SUBSET.OF.TOTAL)
>> 
>> but R does not eliminate the remaining levels of FactorX, just assigns
>> 'not
>> available' to the data. Like this, the other levels still show up in
>> plots
>> etc., but without data entries. Anybody got a solution how to subset the
>> data so that I eliminate the other levels completely?
>> 
>> Thanks a lot for the help,
>> 
> 
> R does not "assign 'not available'" (look at the subsetted data).
> 
> However, factors do not lose levels just because they are not present in 
> a subset of data. There are good reasons for that, but let's not go 
> there this time (look in the list archives if you care). To get rid of 
> unwanted levels, use
> 
> FactorXX <- factor(FactorX, levels=c("Level1","Level2"))
> 
> or just factor(FactorX) if you know that both levels are present (or 
> don't care).
> 
> 
> -- 
>     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 at biostat.ku.dk)              FAX: (+45) 35327907
> 
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> 

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