[R] substituting level for NA in factor column

[David Winsemius]

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



-- 
David.

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