[R] Recode factors

[Doran, Harold]

Perfect. My headache is gone. Thanks. 

> -----Original Message-----
> From: Henrique Dallazuanna [mailto:wwwhsd at gmail.com] 
> Sent: Thursday, March 27, 2008 12:50 PM
> To: Doran, Harold
> Cc: r-help at r-project.org
> Subject: Re: [R] Recode factors
> 
> If I understand, you can try this:
> 
> levels(x)[is.na(as.numeric(levels(x)))] <- 0
> 
> On 27/03/2008, Doran, Harold <HDoran at air.org> wrote:
> > I know this comes up, but I didn't see my exact issue in 
> the archives. 
> > I  have variables in a dataframe that need to be recoded. 
> Here is what 
> > I'm  dealing with
> >
> >  I have a factor called aa
> >
> >  > class(aa)
> >  [1] "factor"
> >  > table(aa)
> >  aa
> >         *    0    1    2    3    A    B    C    D    L    N    T
> >    0    0 1908  725 2089    0    0   67    0    0    2    1    6
> >
> >  I need to recode everything that is not a numeric value 
> into a 0. So,  
> > for example
> >
> >  > mm <- ifelse(aa == 'B', 0, aa)
> >  > table(mm)
> >  mm
> >    0    3    4    5   11   12   13
> >   67 1908  725 2089    2    1    6
> >
> >  The recoding works, but the values are no longer what they were  
> > previously. For example, what was a '1' is now a '4' etc. 
> Is there a 
> > way  to recode factors and also keep the values the same as 
> they were before?
> >  That is, a '1' would remain a '1' after the recode?
> >
> >  After the recoding, I need to convert to a numeric 
> variable. I can do  
> > this as
> >
> >  mm <- as.numeric(as.character(aa))
> >
> >  Harold
> >
> >
> >  > sessionInfo()
> >  R version 2.6.2 (2008-02-08)
> >  i386-pc-mingw32
> >
> >  locale:
> >  LC_COLLATE=English_United States.1252;LC_CTYPE=English_United
> >  States.1252;LC_MONETARY=English_United
> >  States.1252;LC_NUMERIC=C;LC_TIME=English_United States.1252
> >
> >  attached base packages:
> >  [1] stats     graphics  grDevices utils     datasets  
> methods   base
> >
> >
> >  other attached packages:
> >  [1] gdata_2.4.0
> >
> >  loaded via a namespace (and not attached):
> >  [1] gtools_2.4.0
> >  >
> >
> >  ______________________________________________
> >  R-help at r-project.org mailing list
> >  https://stat.ethz.ch/mailman/listinfo/r-help
> >  PLEASE do read the posting guide 
> > http://www.R-project.org/posting-guide.html
> >  and provide commented, minimal, self-contained, reproducible code.
> >
> 
> 
> --
> Henrique Dallazuanna
> Curitiba-Paraná-Brasil
> 25° 25' 40" S 49° 16' 22" O
>