trouble with the 'exclude' parameter of factor() (PR#265)

[ripley@stats.ox.ac.uk]

On Thu, 2 Sep 1999 gautier@lion-ag.de wrote:

> Full_Name: Laurent Gautier
> Version: 0.65.0
> OS: Irix 6.5
> Submission from: (NULL) (195.110.4.98)
> 
> 
> the following doesn't give what I expect
> 
> > test _ factor(ORGMORE[[1]],exclude=c(NA,"NOM"))
> Warning message: 
> NAs introduced by coercion 
> > levels(test)
> [1] "CYT" "EXC" "MEM" "NOM" "NUC" "SEC"

For another posting of yours, I assume the x argument is a factor.
Now ?factor is missing an arguments section, but if x is a factor,
exclude has to be a factor too (with the same set of levels plus perhaps
NA), or coercible to factor codes.  So please try

factor(as.character(ORGMORE[[1]]), exclude=c(NA,"NOM"))

> while this works...
> 
> > test _ factor(ORGMORE[[1]],levels=c("CYT","EXEC","MEM","NUC","SEC"),exclude=NA)
> > levels(test)
> [1] "CYT"  "EXEC" "MEM"  "NUC"  "SEC" 
> 
> 
> All apologies if I misunderstood the help page for the factor() function and
> this is not strange...
> (I mean the results obtained, not my understanding of the help pages  =)    ).

We definitely need to document the arguments, probably make this 
friendlier.

PS: as Irix 6.5 is not in the PLATFORMS list, please do us a favour and
submit a PLATFORMS report.


-- 
Brian D. Ripley,                  ripley@stats.ox.ac.uk
Professor of Applied Statistics,  http://www.stats.ox.ac.uk/~ripley/
University of Oxford,             Tel:  +44 1865 272861 (self)
1 South Parks Road,                     +44 1865 272860 (secr)
Oxford OX1 3TG, UK                Fax:  +44 1865 272595


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