[R] How to exclude a level from a factor

[Uwe Ligges]

Qiong Yang wrote:

> Hi,
> 
> I could not use 'exlcude=' option in factor()
> to exclude a level from a existing factor.
> 
> x is a factor:
> 
> 
>>x
> 
> [1] a b c
> Levels: a b c
> 
> 
>>factor(x,exclude="c")
> 
> [1] a b c
> Levels: a b c
> Warning message:
> NAs introduced by coercion
> 
> However, "c" is not coded as NA.
> 
> The following does not work either:
> 
> 
>>factor(x,exclude=factor("c",levels=c("a","b","c")))
> 
> [1] a b c
> Levels: a b c
> 
> 
> What's wrong with my codes?


  factor(x, levels=letters[1:2])

Uwe Ligges

> Thanks for any help
> 
> Qiong Yang
> 
> ______________________________________________
> R-help at stat.math.ethz.ch mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html