[R] levels in dataframes

[Peter Alspach]

Georg

One way is to call factor() on the subsetted object.

> georg <- factor(LETTERS[1:4])
> summary(georg)
A B C D 
1 1 1 1 
> georg <- georg[georg!='A']
> summary(georg) # the level is still there
A B C D 
0 1 1 1 
> georg <- factor(georg)
> summary(georg) # now it is gone
B C D 
1 1 1 

HTH ....

Peter Alspach
 

> -----Original Message-----
> From: r-help-bounces at r-project.org 
> [mailto:r-help-bounces at r-project.org] On Behalf Of Georg Ehret
> Sent: Wednesday, 23 April 2008 8:58 a.m.
> To: r-help
> Subject: [R] levels in dataframes
> 
> Dear R community,     I wish to ask a short question 
> concerning factor-data
> in dataframes: When I subset the data and get rid of all data 
> for one level, I still retain the level name (obtained by 
> levels(dataframe$variablename) ).
> Is there a convenient way to get rid of the levels for which 
> all data has been deleted?
> Thank you and wishing you an excellent day!
> Georg.
> ****************************************************
> Georg Ehret
> Johns Hopkins
> Baltimore, US
> 
> 	[[alternative HTML version deleted]]
> 
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