[R] factors and ops

[Petr Pikal]

Hi


On 26 May 2006 at 1:33, Erin Hodgess wrote:

Date sent:      	Fri, 26 May 2006 01:33:34 -0500
From:           	Erin Hodgess <hodgess at gator.dt.uh.edu>
To:             	r-help at stat.math.ethz.ch
Subject:        	[R]  factors and ops

> Dear R People
> 
> I have a variable which is an ID number that is a factor.
> 
> I would like to look for ID numberbs that are greeater than
> a particular value.
> 
> However, factors are a big ugly for these operations.
> 
> I was messing with the HR data set from the SASmixed package.
> 
> HR$Patient is a factor like that.
> 
> Now if I used:
> subset(HR,as.integer(as.character(Patient)) > 214)
> 
> that will work.

AFAIK no other way. If you know you do not want HR$Patient as factor 
you can use 
HR$Patient <- as.integer(as.character(HR$Patient))
or
 HR$Patient <- as.numeric(as.character(HR$Patient)) 
and then
subset(HR,Patient > 214)

but beware of attaching data.frame as if it is attached you need to 
detach it first and than to change factor to numeric and only then to 
attach it again.

HTH
Petr


> 
> If seems to me that there may be a better way.
> Is that true?
> 
> R Version 2.3.0 Windows
> 
> Thanks in advance!
> 
> 
> sincerely,
> Erin Hodgess
> Associate Professor
> Department of Computer and Mathematical Sciences
> University of Houston - Downtown
> mailto: hodgess at gator.uhd.edu
> 
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Petr Pikal
petr.pikal at precheza.cz