Re: R-beta: bugs and problems

Thomas Lumley (thomas@biostat.washington.edu)
Tue, 2 Jun 1998 09:49:41 -0700 (PDT)


Date: Tue, 2 Jun 1998 09:49:41 -0700 (PDT)
From: Thomas Lumley <thomas@biostat.washington.edu>
To: Jim Lindsey <jlindsey@luc.ac.be>
Subject: Re: R-beta: bugs and problems
In-Reply-To: <9806020712.AA26573@alpha.luc.ac.be>

On Tue, 2 Jun 1998, Jim Lindsey wrote:

> 
> 3. To obtain the codes of a factor variable, one uses as.numeric().
> However, this function destroys the properties of the matrix, turning
> it into a vector.
>   Factors are very useful, but they are presently a mess for anything
> except simple applications in lm/glm.


You can use codes() to extract the codes of a factor variable while
keeping the matrix structure
R> matrix(factor(1:10),2,5)->a
R> codes(a)
     [,1] [,2] [,3] [,4] [,5]
[1,]    1    3    5    7    9
[2,]    2    4    6    8   10


The other problems need more fixing.  


Thomas Lumley
UW Biostatistics

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