[R] Generate object names from variables

[Marc Schwartz (via MN)]

On Fri, 2006-07-14 at 16:57 +0200, Georg Otto wrote:
> Hi,
> 
> I want to generate object names out of variables in a sort of variable
> substitution.
> 
> first i generate some vectors and an empty list:
> 
> > vector.a<-c("a","b")
> > vector.b<-c("c","d")
> > vector.c<-c("e","f")
> > vectors<-c("vector.a", "vector.b", "vector.c")
> > vectors
> [1] "vector.a" "vector.b" "vector.c"
> 
> > vectorlist<-list()
> 
> What I would then like to do is to generate elements of the list by
> using variables, somehow like this (does not work):
> 
> >for (i in vectors) {
> + list$i<-i
> + }
> 
> To end up with a list like this:
> 
> > list
> $vector.a
>  [1] "a" "b"
> $vector.b
>  [1] "c" "d"
> $vector.c
>  [1] "e" "f"
> 
> 
> Any hint will be appreciated.
> 
> Cheers,
> 
> Georg

Presuming that your vectors fit a naming pattern of "vector.x":

# Use grep() to get the vector names from ls()
> vectors <- grep("vector[\.]", ls(), value = TRUE)

> vectors
[1] "vector.a" "vector.b" "vector.c"

# Use sapply to create the list
> sapply(vectors, get, simplify = FALSE)
$vector.a
[1] "a" "b"

$vector.b
[1] "c" "d"

$vector.c
[1] "e" "f"


HTH,

Marc Schwartz