[R] Function similar to combine.levels in Hmisc package

[Saeed Abu Nimeh]

Is there a function similar to combine.levels ( in the Hmisc package)
that combines the levels of factors, but not based on their frequency.
Alternatively, I am looking into using the significance of the dummy
variables of factors based on their Pr(>|t|) value using the linear
model, then deleting the non-significant levels. Any other
suggestions?
Thanks,
Saeed