[R] substituting level for NA in factor column

Petr PIKAL petr.pikal at precheza.cz
Wed Jan 19 09:06:45 CET 2011


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
> > EEO Counselor
> > National Park Service
> > Cumberland Piedmont Network
> > P.O. Box 8
> > Mammoth Cave, KY 42259
> > Ph: 270-758-2163
> > Lab: 270-758-2151
> > Fax: 270-758-2609
> > ****************************************************************
> > Science, in constantly seeking real explanations, reveals the true 
> > majesty
> > of our world in all its complexity.
> > -Richard Dawkins
> >
> > The scientific tradition is distinguished from the pre-scientific 
> > tradition
> > in having two layers.  Like the latter it passes on its theories but 
> > it
> > also passes on a critical attitude towards them.  The theories are 
> > passed
> > on not as dogmas but rather with the challenge to discuss them and 
> > improve
> > upon them.
> > -Karl Popper
> >
> > ...consider yourself a guest in the home of other creatures as 
> > significant
> > as yourself.
> > -Wayside at Wilderness Threshold in McKittrick Canyon, Guadalupe 
> > Mountains
> > National Park, TX
> >
> > Cumberland Piedmont Network (CUPN) Homepage:
> > http://tiny.cc/e7cdx
> >
> > CUPN Forest Pest Monitoring Website:
> > http://bit.ly/9rhUZQ
> >
> > CUPN Cave Cricket Monitoring Website:
> > http://tiny.cc/ntcql
> >
> > CUPN Cave Aquatic Biota Monitoring Website:
> > http://tiny.cc/n2z1o
> >
> > ______________________________________________
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> 
> David Winsemius, MD
> West Hartford, CT
> 
> ______________________________________________
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