[R] Re moving levels of a factor

[Uwe Ligges]

Dieter Menne wrote:
> 
> 
> 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.
>


or  a[-1, drop=TRUE]

Uwe Ligges

> Dieter