R help - Apr 2008 - Subset: data frames and factor levels

Hi!

I'm doing:
etni <- subset(etni, NAMECOM!="Maniquisito")

where etni is a data.frame, NAMECOM a factor and "Maniquisito" labels
a row that I want to delete.

The problem is that while the row is deleted, the factor level is still 
there (I can see "Maniquisito" if I do levels(etni$NAMECOM) ).

I know I can get the appropriate levels by:
levels(factor(etni$NAMECOM))
so I could
etni$NAMECOM <- factor(etni$NAMECOM)

but there are other columns in etni that are factors as well. Do I have 
to take
care of each factor column? Should not subset take care of recalculating
the factor levels automatically?

Thanks!

Agus
-- 
Dr. Agustin Lobo
Institut de Ciencies de la Terra "Jaume Almera" (CSIC)
LLuis Sole Sabaris s/n
08028 Barcelona
Spain
Tel. 34 934095410
Fax. 34 934110012
email: Agustin.Lobo at ija.csic.es
http://www.ija.csic.es/gt/obster

On Tuesday 01 April 2008 09:43:00 am Agustin Lobo wrote:
AL> I'm doing:
AL> etni <- subset(etni, NAMECOM!="Maniquisito")
AL>
AL> where etni is a data.frame, NAMECOM a factor and "Maniquisito"
labels
AL> a row that I want to delete.
AL>
AL> The problem is that while the row is deleted, the factor level is still
AL> there (I can see "Maniquisito" if I do levels(etni$NAMECOM) ).

See
http://wiki.r-project.org/rwiki/doku.php?id=tips:data-manip:drop_unused_levels

Stefan



-- 
Microeconomics
University of Erfurt