[R] renaming factor-labels / add factors etc.

[Peter Alspach]

Jörg

To add a level you could:

x <- factor(c("xyz1", "abc1", "xyz2", "abc2"))
x1 <- factor(x, levels=c(levels(x), 'fgh'))
summary(x)
abc1 abc2 xyz1 xyz2 
   1    1    1    1 
summary(x1)
abc1 abc2 xyz1 xyz2  fgh 
   1    1    1    1    0 

For the others, I tend to convert to a character, make the changes and convert back to a factor - but there is probably a better way.

HTH ....

Peter Alspach.

> -----Original Message-----
> From: r-help-bounces at r-project.org 
> [mailto:r-help-bounces at r-project.org] On Behalf Of Jörg Groß
> Sent: Tuesday, 16 December 2008 3:26 p.m.
> To: r-help at r-project.org
> Subject: [R] renaming factor-labels / add factors etc.
> 
> Hi,
> 
> how can I change a defined factor-variable?
> Like adding levels, renaming existing levels or merge several 
> levels of a factor to one level?
> 
> 
> 
> For example; following factor-variable is given:
> 
>   x <- factor(c("xyz1", "abc1", "xyz2", "abc2"))
> 
> 
> How can I add the level fgh?
> And how can I merge "xyz1" and "xyz2" to one level?
> And how can I change the name?
> 
> 
> 
> 
> Thanks for any help!
> 
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> PLEASE do read the posting guide 
> http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
> 

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