[R] removing NA as a level

[Chuck Cleland]

dat$x.f <- factor(replace(dat$x.f, dat$x.f == "NA", NA))

Anne wrote:
> Dear R-helpers,
> I have a problem which I suppose is trivila, but...
> I have included NA values as factors ( (to be able to make nice printed summaries with NAs % ba category ) with the following code
> 
> dat$x.f<-factor(dat$x, exclude=NULL); levels(dat$x.f)<-c("A1","A2","A3","A4","NA"); length(dat$x.f)
> 
> Now, I want to impute the missing values. Is there a nice way to drop the NA factor instead of rewriting something of the sort 
>  dat$x.f<-factor(dat$x); levels(dat$x.f)<-c("A1","A2","A3","A4"); length(dat$x.f)?

-- 
Chuck Cleland, Ph.D.
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