> -----Original Message-----
> From: r-help-boun...@r-project.org
> [mailto:r-help-boun...@r-project.org] On Behalf Of tdm
> Sent: Monday, October 12, 2009 12:22 AM
> To: r-help@r-project.org
> Subject: Re: [R] field index given name.
>
>
> Thanks - would never have guessed that. I eventually got the
> following to do
> what I want...
>
> > colprob <- array(dim=NCOL(iris))
> > for(i in 1:NCOL(iris)){
> + colprob[i]=
> + ifelse(names(iris)[i] == 'Species',1,0.5)
> + }
> > colprob
> [1] 0.5 0.5 0.5 0.5 1.0
I think a more direct way to do what that does
is to make vector with names, where the names
are the column names of 'iris' and then subscript
the vector by name instead of by number. E.g.,
> colprob <- rep(0.5, length=ncol(iris)) # initialize probs
> names(colprob) <- colnames(iris) # initialize names
> colprob["Species"] <- 1.0 # change prob for "Species"
> colprob
Sepal.Length Sepal.Width Petal.Length Petal.Width Species
0.5 0.5 0.5 0.5 1.0
> colprob["Sepal.Width"] # example prob for "Sepal.Width"
Sepal.Width
0.5
Bill Dunlap
Spotfire, TIBCO Software
wdunlap tibco.com
>
>
>
>
> Schalk Heunis-2 wrote:
> >
> > Hi Phil
> > Try the following
> >> which(names(iris)=='Species')
> > [1] 5
> >
> > HTH
> > Schalk Heunis
> >
> > On Mon, Oct 12, 2009 at 8:53 AM, tdm <ph...@philbrierley.com> wrote:
> >
> >>
> >> Hi,
> >>
> >> How do I access the index number of a field given I only
> know the field
> >> name?
> >>
> >> eg - I want to set the probability of the field 'species'
> higher than the
> >> other fields to use in sampling.
> >>
> >> > colprob <- array(dim=NCOL(iris))
> >> > for(i in 1:NCOL(iris)){colprob[i]=0.5}
> >> > colprob[iris$species] = 1 #this doesn't work
> >> > colprob
> >> [1] 0.5 0.5 0.5 0.5 0.5
> >>
> >>
> >>
> >>
> >>
> >> --
> >> View this message in context:
> >>
> http://www.nabble.com/field-index-given-name.-tp25851216p25851216.html
> >> Sent from the R help mailing list archive at Nabble.com.
> >>
> >> ______________________________________________
> >> R-help@r-project.org mailing list
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> >> PLEASE do read the posting guide
> >> http://www.R-project.org/posting-guide.html
> >> and provide commented, minimal, self-contained, reproducible code.
> >>
> >
> > [[alternative HTML version deleted]]
> >
> > ______________________________________________
> > R-help@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.
> >
> >
>
> --
> View this message in context:
> http://www.nabble.com/field-index-given-name.-tp25851216p25851466.html
> Sent from the R help mailing list archive at Nabble.com.
>
> ______________________________________________
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