Re: [R] with lapply() how can you retrieve the name of the object

From: Jorge Ivan Velez <jorgeivanvelez_at_gmail.com>
Date: Fri, 18 Jul 2008 19:02:37 -0400

Dear Andrew,

Following Jim Holtman' solution (thanks for pointed it out), try:

a <- data.frame(var.1 = 1:5)
b <- data.frame(var.1 = 11:15)
test.list <- list(a=a, b=b)
do.call(rbind,lapply(names(test.list), function(x){

     cbind(test.list[[x]], var.2=x)
}))

HTH, Jorge

On Fri, Jul 18, 2008 at 6:57 PM, jim holtman <jholtman_at_gmail.com> wrote:

> Is this what you wanted; you would use the 'names' to get the names in
> the lapply:
>
> > lapply(names(test.list), function(x){
> + cbind(test.list[[x]], var.2=x)
> + })
> [[1]]
> var.1 var.2
> 1 1 a
> 2 2 a
> 3 3 a
> 4 4 a
> 5 5 a
>
> [[2]]
> var.1 var.2
> 1 11 b
> 2 12 b
> 3 13 b
> 4 14 b
> 5 15 b
>
>
>
> On Fri, Jul 18, 2008 at 6:31 PM, Jorge Ivan Velez
> <jorgeivanvelez_at_gmail.com> wrote:
> > Dear Andrew,
> >
> > It's not the best solution but it does what you need:
> >
> > a <- data.frame(var.1 = 1:5)
> > b <- data.frame(var.1 = 11:15)
> > test.list <- list(a=a, b=b)
> > res=do.call(rbind,test.list)
> > res$var.2=substr(rownames(res),1,1)
> > rownames(res)=NULL
> > res
> >
> >
> > HTH,
> >
> > Jorge
> >
> >
> > On Fri, Jul 18, 2008 at 6:21 PM, Andrew Yee <yee_at_post.harvard.edu>
> wrote:
> >
> >> In the following code, I'd like to be able to create a new variable
> >> containing the value of the names of the list.
> >>
> >>
> >> a <- data.frame(var.1 = 1:5)
> >> b <- data.frame(var.1 = 11:15)
> >>
> >> test.list <- list(a=a, b=b)
> >>
> >> # in this case, names(test.list) is "a" and "b"
> >>
> >> # and I'd like to use lapply() so that
> >> # I get something that looks like
> >> # var.1 var.2
> >> # 1 a
> >> # 2 a
> >> # 3 a
> >> #etc.
> >>
> >> new.list <- lapply(test.list, function(x) {x$var.2 <- names(x)
> >> x} )
> >>
> >>
> >> # the above clearly doesn't do it. How do you pull out the names of the
> >> thing that is being lapplied?
> >>
> >> Thanks,
> >> Andrew
> >>
> >> [[alternative HTML version deleted]]
> >>
> >> ______________________________________________
> >> 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.
> >>
> >
> > [[alternative HTML version deleted]]
> >
> > ______________________________________________
> > 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.
> >
>
>
>
> --
> Jim Holtman
> Cincinnati, OH
> +1 513 646 9390
>
> What is the problem you are trying to solve?
>

        [[alternative HTML version deleted]]



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