[R] Re moving levels of a factor

Dieter Menne dieter.menne at menne-biomed.de
Wed Nov 11 08:27:09 CET 2009




Henrik Wahren wrote:
> 
> How can one or more levels be removed from a factor of a data frame. There
> was a similar post on how to do this when a factor meets some criterion
> (e.g. <= 2), but I can¹t seem to get that solution to work.
> Here, I simply want to drop some levels.
> 
> 

Simply call factor again on the reduced set

a = factor(c("a","b","b","b"))
a[-1]
factor(a[-1])

If a is in a data frame, replace a by by df$a.

Dieter
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