[R] strange split behavior?

[Petr PIKAL]

Hi

r-help-bounces at r-project.org napsal dne 23.09.2009 14:49:38:

> On Wed, Sep 23, 2009 at 07:29:30AM -0500, Peng Yu wrote:
> > On Wed, Sep 23, 2009 at 1:24 AM, Peter Dalgaard
> > <p.dalgaard at biostat.ku.dk> wrote:
> > > Peng Yu wrote:
> > 
> > Is there an operation on a factor to get a subset and keep only the
> > corresponding levels (see commented line below)?
> 
> Yes, there is: call factor() on your subset:
> 
> > a <- factor(rep(letters[1:5], 5))
> > a
>  [1] a b c d e a b c d e a b c d e a b c d e a b c d e
> Levels: a b c d e
> > b <- a[a!='b']

Or use drop argument

b <- a[a!='b', drop=TRUE]

regards
Petr


> > b
>  [1] a c d e a c d e a c d e a c d e a c d e
> Levels: a b c d e
> > factor(b)
>  [1] a c d e a c d e a c d e a c d e a c d e
> Levels: a c d e
> 
> 
> cu
>    Philipp
> 
> -- 
> Dr. Philipp Pagel
> Lehrstuhl für Genomorientierte Bioinformatik
> Technische Universität München
> Wissenschaftszentrum Weihenstephan
> 85350 Freising, Germany
> http://webclu.bio.wzw.tum.de/~pagel/
> 
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