Hi Paul and Jim,
Thanks for your messages.
I just wanted R to give me the columns of my data frame d, whose names
appear in v. I do not care about the names of v that are not in d. In
addition, every time, there will be at least one element of v that has a
corresponding column in d, for sure, so I know there is at least one match
between the 2.
Initially, I tried something in the spirit:
sub<- subset(d, colnames(d) %in% v)
but I could not make it work properly.
Best,
Aurelien
2011/12/2 Paul Hiemstra <paul.hiems...@knmi.nl>
> On 12/02/2011 07:20 AM, Aurélien PHILIPPOT wrote:
> > Dear R-users,
> > -I am new to R, and I am struggling with the following problem.
> >
> > -I am repeating the following operations hundreds of times, within a
> loop:
> > I want to subset a data frame by columns. I am interested in the columns
> > names that are given by the rows of another data frame that was built in
> > parallel. The solution I have so far works well as long as the elements
> of
> > the second data frame are included in the column names of the first data
> > frame but if an element from the second object is not a column name of
> the
> > first one, then it bugs.
>
> Hi Aurelien,
>
> I would call this a feature, not a bug. I think R does what it should
> do, you request a non-existent column and it throws an error. What kind
> of behavior are you looking for instead of this error?
>
> regards,
> Paul
>
> >
> > -More concretely, I have the following data frames d and v:
> > yyyymmdd<-c("19720601", "19720602", "19720605")
> > sret.10006<-c(1,2,3)
> > sret.10014<-c(5,9,7)
> > sret.10065<-c(10,2,11)
> >
> >
> > d<- data.frame(yyyymmdd=yyyymmdd, sret.10006=sret.10006,
> > sret.10014=sret.10014, sret.10065=sret.10065)
> >
> > v<- data.frame(V1="sret.10006", V2="sret.10090")
> > v<- sapply(v, function(x) levels(x)[x])
> >
> > -I want to do the following subsetting:
> > sub<- subset(d, select=c(v))
> >
> >
> > and I get the following error message:
> > Error in `[.data.frame`(x, r, vars, drop = drop) :
> > undefined columns selected
> >
> >
> >
> > Any help would be very much appreciated,
> >
> > Best,
> > Aurelien
> >
> > [[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.
>
>
> --
> Paul Hiemstra, Ph.D.
> Global Climate Division
> Royal Netherlands Meteorological Institute (KNMI)
> Wilhelminalaan 10 | 3732 GK | De Bilt | Kamer B 3.39
> P.O. Box 201 | 3730 AE | De Bilt
> tel: +31 30 2206 494
>
> http://intamap.geo.uu.nl/~paul
> http://nl.linkedin.com/pub/paul-hiemstra/20/30b/770
>
>
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