[R] substituting level for NA in factor column

[Petr PIKAL]

Hi

r-help-bounces at r-project.org napsal dne 19.01.2011 00:03:10:

> 
> On Jan 18, 2011, at 5:25 PM, Kurt_Helf at nps.gov wrote:
> 
> > Greetings
> >     I have a bunch of NAs in a column of categorical variables 
> > designating
> > the size classes (e.g., smallest to largest: 1,2,3,4) of cave 
> > crickets.
> > I'd like to substitute "U" (for unknown) for the NAs.  Can anyone 
> > give me
> > an idea how to do this?  Thanks in advance.
> 
>  > vect=factor(c(1,2,3,4,NA))
>  > vect
> [1] 1    2    3    4    <NA>
> Levels: 1 2 3 4
>  > levels(vect) <- c(levels(vect), "U")
>  > vect[is.na(vect)] <- "U"
>  >
>  > vect
> [1] 1 2 3 4 U
> Levels: 1 2 3 4 U

You can set also NA as an additional level through exclude=NULL option
factor(vect, exclude=NULL)
[1] 1    2    3    4    <NA>
Levels: 1 2 3 4 <NA>

Regards
Petr



> 
> 
> 
> -- 
> David.
> 
> > Cheers
> > Kurt
> >
> > ***************************************************************
> > Kurt Lewis Helf, Ph.D.
> > Ecologist
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> David Winsemius, MD
> West Hartford, CT
> 
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