levels
attribute of
object
are pruned to contain
only the levels occurring in the factor.
pruneLevels(object)
factor
.
object
, but with the
levels
attribute containing only value occurring in the factor.
f1 <- factor(c(1,1,2,3,3,4,5)) levels(f1) f2 <- f1[4:7] levels(f2) levels(pruneLevels(f2))