[R] Excluding levels in table and xtabs

[kjetil halvorsen]

Hola!

Thomas Lumley wrote:
> 
> On Wed, 11 Dec 2002, Michael Friendly wrote:
> 
> > I'm trying to form contingincy tables among a set of character variables
> > which were read from a .csv file and
> > have missing represented as "".  I want to exclude the missing levels
> > from the table.
> 
> I think this is a bug. The exclude= argument doesn't work for factors,
> because the argument is passed to factor(), and its exclude argument has
> a different format when the main argument is a factor. 

I dot think that is correct. table doesnt call factor on factors, so the
exclude argument doesnt get used at all. I had the oposite problem as
the original poster.
To include NA's as a level in a table. Why should't table simply call
factor also on factor arguments, so the exclude argument to table get
used in this case to. I modifyed table to Table doing this, and it
works, the only problem being that NA is not labelled in the table.

Kjetil Halvorsen


 
> 
>         -thomas
> 
> >
> > > levels(CPIC)
> > [1] ""  "N" "Y"
> > > levels(Manix)
> > [1] ""  "N" "Y"
> > > xtabs(~CPIC + Manix, exclude=c("",NA))
> >     Manix
> > CPIC        N    Y
> >      272    4   15
> >    N 154 2812 1472
> >    Y 158  466 4870
> >
> > > table(CPIC, Manix, exclude=c("",NA))
> >
> >     Manix
> > CPIC        N    Y
> >      272    4   15
> >    N 154 2812 1472
> >    Y 158  466 4870
> >
> > The only way I can exclude them is by
> >
> > t <- table(CPIC, Manix)
> > t <- t[-1,-1]
> >
> > that's not to hard in this case, but my application is to a much
> > larger table where this gets unweildly.
> >
> > --
> > Michael Friendly              friendly at yorku.ca
> > York University               http://www.math.yorku.ca/SCS/friendly.html
> > Psychology Department
> > 4700 Keele Street             Tel:  (416) 736-5115 x66249
> > Toronto, Ontario, M3J 1P3     Fax:  (416) 736-5814
> >
> > ______________________________________________
> > R-help at stat.math.ethz.ch mailing list
> > http://www.stat.math.ethz.ch/mailman/listinfo/r-help
> >
> 
> Thomas Lumley                   Asst. Professor, Biostatistics
> tlumley at u.washington.edu        University of Washington, Seattle
> ^^^^^^^^^^^^^^^^^^^^^^^^
> -- NOTE NEW EMAIL ADDRESS
> 
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