[R] modifying colnames of tables in a loop

[Gabor Grothendieck]

Try this:


tb1 <- tb2 <- tb3 <- matrix(1:100, 10, 10, dim = list(NULL,
LETTERS[1:10]))

head(tb1)

lis <- c("tb1", "tb2", "tb3")

for(d in lis) colnames(.GlobalEnv[[d]]) <- tolower(colnames(.GlobalEnv[[d]]))

head(tb1)





lis <- list(tb1 = data.frame(1:100, 10, dim = list(NULL, LETTERS[1:10]), 3)
lis <- c(lis, tb2 = lis$tb1, tb3



On 11/16/06, Werner Wernersen <pensterfuzzer at yahoo.de> wrote:
> Thanks Phil and Dimitris!
>
> This works perfectly!
> At this stage I am not concerned about efficiency
> although I am curious if there is a way to do without
> copying, for instance with pointers like in C.
>
> Thanks again,
>  Werner
>
>
> --- Dimitris Rizopoulos
> <dimitris.rizopoulos at med.kuleuven.be> schrieb:
>
> > try the following (untested):
> >
> > tb1 <- tb2 <- tb3 <- matrix(1:100, 10, 10, dim =
> > list(NULL,
> > LETTERS[1:10]))
> >
> > lis <- list("tb1", "tb2", "tb3")
> > for(i in seq(lis)){
> >     tb <- get(lis[[i]])
> >     colnames(tb) <- tolower(colnames(tb))
> >     assign(lis[[i]], tb)
> > }
> >
> >
> > I hope it helps.
> >
> > Best,
> > Dimitris
> >
> > ----
> > Dimitris Rizopoulos
> > Ph.D. Student
> > Biostatistical Centre
> > School of Public Health
> > Catholic University of Leuven
> >
> > Address: Kapucijnenvoer 35, Leuven, Belgium
> > Tel: +32/(0)16/336899
> > Fax: +32/(0)16/337015
> > Web: http://med.kuleuven.be/biostat/
> >
> >
> http://www.student.kuleuven.be/~m0390867/dimitris.htm
> >
> >
> > ----- Original Message -----
> > From: "Werner Wernersen" <pensterfuzzer at yahoo.de>
> > To: "Benilton Carvalho" <bcarvalh at jhsph.edu>
> > Cc: <r-help at stat.math.ethz.ch>
> > Sent: Thursday, November 16, 2006 4:06 PM
> > Subject: Re: [R] modifying colnames of tables in a
> > loop
> >
> >
> > > That's almost perfect! Only the operation
> > > colnames(get(x)) <-
> > > seems not to be defined.
> > >
> > > Now I can't figure out how to assign the colnames
> > of
> > > the object in the original environment.
> > >
> > > Thanks, Benilton!
> > >
> > > --- Benilton Carvalho <bcarvalh at jhsph.edu>
> > schrieb:
> > >
> > >> how about:
> > >>
> > >> for (x in l) colnames(get(x)) <-
> > >> lower.case(colnames(get(x)))
> > >>
> > >> b
> > >>
> > >> On Nov 16, 2006, at 9:01 AM, Werner Wernersen
> > wrote:
> > >>
> > >> > Hi,
> > >> >
> > >> > I have a list with the names of tables, e.g.
> > >> > l <- c("t1","t2","t3")
> > >> > and I want to change the colnames of each of
> > the
> > >> > tables in a for loop like this:
> > >> > for (x in l) {
> > >> >     colnames(eval(x)) <-
> > >> lower.case(colnames(eval(x)))
> > >> > }
> > >> >
> > >> > This does not work but could someone give me
> > some
> > >> help
> > >> > to get on the right track?
> > >> >
> > >> > Thanks a million,
> > >> >   Werner
> > >> >
> > >> > ______________________________________________
> > >> > R-help at stat.math.ethz.ch 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.
> > >>
> > >
> > > ______________________________________________
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> > >
> >
> >
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