> -----Original Message-----
> From: r-help-boun...@r-project.org [mailto:r-help-boun...@r-project.org] On
> Behalf Of David Winsemius
> Sent: Monday, July 25, 2011 3:39 PM
> To: Anthony Damico
> Cc: r-help@r-project.org
> Subject: Re: [R] Recoding Multiple Variables in a Data Frame in One Step
>
>
> On Jul 21, 2011, at 8:06 PM, Anthony Damico wrote:
>
> > Hi, I can't for the life of me find how to do this in base R, but
> > I'd be
> > surprised if it's not possible.
> >
> > I'm just trying to replace multiple columns at once in a data frame.
> >
> > #load example data
> > data(api)
> >
> > #this displays the three columns and eight rows i'd like to replace
> > apiclus1[ apiclus1$meals > 98 , c( "pcttest" , "api00" ,
> > "sch.wide" ) ]
> >
> >
> > #the goal is to replace pcttest with 100, api100 with NA, and
> > sch.wide with
> > "Maybe"
> >
> > #this doesn't work--
> > apiclus1[ apiclus1$meals > 98 , c( "pcttest" , "api00" ,
> > "sch.wide" ) ] <-
> > c( 100 , NA , "Maybe" )
Try list(pcttest=100, api00=NA, sch.wide="Maybe") instead
of c(100, NA, "Maybe") as the new value.
Here is a self-contained example
> df <- data.frame(Size=sin(1:10), Name=state.name[11:20], Value=11:20,
> stringsAsFactors=FALSE)
> df[df$Size<0, c("Name", "Value")] <- list(Name="JUNK", Value=-99)
> df
Size Name Value
1 0.8414710 Hawaii 11
2 0.9092974 Idaho 12
3 0.1411200 Illinois 13
4 -0.7568025 JUNK -99
5 -0.9589243 JUNK -99
6 -0.2794155 JUNK -99
7 0.6569866 Kentucky 17
8 0.9893582 Louisiana 18
9 0.4121185 Maine 19
10 -0.5440211 JUNK -99
Bill Dunlap
Spotfire, TIBCO Software
wdunlap tibco.com
> >
> > #the results replace downward instead of across
> > apiclus1[ apiclus1$meals > 98 , c( "pcttest" , "api00" ,
> > "sch.wide" ) ]
>
> If I had noted that I would have tried this:
>
> apiclus1[ apiclus1$meals > 98 , rep( c( "pcttest" , "api00" ,
> "sch.wide" ),
> each = sum(apiclus1$meals > 98)
> ) ]
>
> Should be pretty easy to test, but since _you_ are the one responsible
> for providing examples for testing when posting to rhelp, I am going
> to throw an untested theory back at you.
>
>
> >
> > I know I can do this with a few more steps (like one variable at a
> > time or
> > by counting the number of rows to replace and then using rep() ..but
> > I'm
> > hoping there's a quicker way?
> >
> >
> > Thanks!!
> >
> > Anthony Damico
>
>
> David Winsemius, MD
> West Hartford, CT
>
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