[R] How to use a for loop to generate two sequences

[Gabor Grothendieck]

On 6/29/06, Xiaohua Dai <ecoinformatics at gmail.com> wrote:
> I followed your method but there was an error on FUN get:
>
> > nm <- paste("test", 1:1000, sep = "")
> > lapply(nm, get)
> Error in get(x, envir, mode, inherits) : variable "test1" was not found
> > L <- sapply(paste("test", 1:1000, sep = ""), get, simplify = FALSE)
> Error in get(x, envir, mode, inherits) : variable "test1" was not found
>
> But lapply(nm, as.name) worked well. Are there any problem with my R env?

These are different things.  Using as.name gives you a list of names
but I am assuming you are looking for a list of the objects themselves
so you need to have those objects defined.  Here is a reproducible
example:

> test1 <- test2 <- 1
> sapply(paste("test", 1:2, sep = ""), get, simplify = FALSE)
$test1
[1] 1

$test2
[1] 1





>
> > traceback()
> 2: FUN(X[[1]], ...)
> 1: lapply(nm, get)
>
> > sessionInfo()
> Version 2.3.1 (2006-06-01)
> i386-pc-mingw32
>
> attached base packages:
> [1] "methods"   "stats"     "graphics"  "grDevices" "utils"     "datasets"
> [7] "base"
>
> > win.version()
> [1] "Windows XP Professional (build 2600) Service Pack 2.0"
>
>
> Thanks
> Xiaohua
>
>
> On 6/30/06, Gabor Grothendieck <ggrothendieck at gmail.com> wrote:
> > A vector of character strings:
> >
> >  nm <- paste("test", 1:1000, sep = "")
> >
> > A list whose components are the objects: test1, test2, ...
> >
> >  lapply(nm, get)
> >
> > or if you do it this way the list will have 'test1', 'test2', ... as the
> > component names:
> >
> >  L <- sapply(paste("test", 1:1000, sep = ""), get, simplify = FALSE)
> >
> > and then
> >
> >  names(L)
> >
> > gives the vector of names.
> >
> >
> > Also note that
> >
> >  apropos("^test[0-9]+")
> >
> > will give a vector of object names corresponding to objects
> >  in the current workspace whose names
> > are "test" followed by a number.
> >
> > On 6/29/06, Xiaohua Dai <ecoinformatics at gmail.com> wrote:
> > > Hi R users,
> > >
> > > Hope the question is not too simple:
> > >
> > > How to use a for loop to generate two lists as below:
> > >
> > > testlist <- list(test1, test2, ..., test1000)
> > > stringlist <- list("test1","test2",...,"test1000")
> > >
> > > Thanks
> > > Xiaohua
> > >
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> > >
>