[R] pooling categories in a table

[Peter Dalgaard BSA]

Peter Dalgaard BSA <p.dalgaard at biostat.ku.dk> writes:

> Robin Hankin <r.hankin at auckland.ac.nz> writes:
> 
> > Peter Dalgaard writes:
> > 
> > > 
> > >  data(UCBAdmissions)
> > >  DF <- as.data.frame(UCBAdmissions)
> > >  DF$Dept <- factor(c(1,2,2,3,4,5)[DF$Dept],
> > >      labels=c("A","B+C","D","E","F"))
> > >  xtabs(Freq~.,DF)
> > > 
> > 
> > 
> > This is simply brilliant.  I found it very very instructive; any
> > chance of adding it to the examples section of xtabs()' help file?
> 
> Not at this stage with 1.5.0 in feature freeze, I think. (Help page
> examples are "features" because they become part of the test suite. An
> unfortunate example could break the test suite on some platforms and
> destabilize the whole process. Of course *this* particular case is
> very likely harmless, but we need hard rules.) We can do it for
> r-devel afterwards.

And BTW, the canonical way of joining factor levels escaped me last
night:

levels(DF$Dept) <- c("A","B+C","B+C","D","E","F")

is usually clearer, unless you have inordinately long level labels.

-- 
   O__  ---- Peter Dalgaard             Blegdamsvej 3  
  c/ /'_ --- Dept. of Biostatistics     2200 Cph. N   
 (*) \(*) -- University of Copenhagen   Denmark      Ph: (+45) 35327918
~~~~~~~~~~ - (p.dalgaard at biostat.ku.dk)             FAX: (+45) 35327907
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