Re: [R] creating named elements of lists on the fly
Ben Shapiro getdown.org> writes:
:
: HI Folks,
:
: I'm trying to create a list with named elements. Only, I don't know the
names of the elements a priori (they
: come from the data being calculated). Currently, my approach is to create an
environment, then assign
: things to the environement, then as.list the environment to get a list.
:
: Running the code gives, for example:
: > e2 <- new.env(FALSE, NULL)
: > assign("dude", 123, env=e2)
: > assign("chick", 456, env=e2)
: > as.list(e2)
: Error in as.vector(x, "list") : cannot coerce to vector
:
: Is this the best way to make a list like this?
:
: Thanks,
: Ben
If you need to add them one at a time then John Fox has
already provided an answer. If you want to create it
all at once and you have the contents in a list and
the names in a vector like this:
nams <- letters[1:3]
contents <- list(1:3, 4:5, 6:9)
# then here are two ways:
# 1
mapply("{", nams, contents, SIMPLIFY = FALSE)
# 2
names(contents) <- nams
contents
# Actually in your example the elements are all homogeneous so
# you could alternately use a vector to hold the results:
# 1a
contents <- c(1, 2, 3)
mapply("{", nams, contents)
# 2a
names(contents) <- nams
contents
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Re: [R] creating named elements of lists on the fly
Ben Shapiro wrote:
HI Folks,
I'm trying to create a list with named elements. Only, I don't know the names of the elements a priori (they come from the data being calculated). Currently, my approach is to create an environment, then assign things to the environement, then as.list the environment to get a list.
Running the code gives, for example:
e2 <- new.env(FALSE, NULL)
assign("dude", 123, env=e2)
assign("chick", 456, env=e2)
as.list(e2)
Error in as.vector(x, "list") : cannot coerce to vector
Is this the best way to make a list like this?
Thanks,
Ben
You can use the "[[" operator for list objects:
nm <- c("dude", "chick")
e2[[nm[1]]] <- 123
e2[[nm[2]]] <- 456
HTH,
--sundar
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RE: [R] creating named elements of lists on the fly
Dear Ben,
Is this the kind of thing you had in mind?
> lst <- list()
> element <- "a"
> lst[[element]] <- 1:5
> element <- "b"
> lst[[element]] <- letters[1:5]
> lst
$a
[1] 1 2 3 4 5
$b
[1] "a" "b" "c" "d" "e"
I hope this helps,
John
> -Original Message-
> From: [EMAIL PROTECTED]
> [mailto:[EMAIL PROTECTED] On Behalf Of Ben Shapiro
> Sent: Friday, October 08, 2004 11:46 AM
> To: [EMAIL PROTECTED]
> Subject: [R] creating named elements of lists on the fly
>
> HI Folks,
>
> I'm trying to create a list with named elements. Only, I
> don't know the names of the elements a priori (they come from
> the data being calculated). Currently, my approach is to
> create an environment, then assign things to the
> environement, then as.list the environment to get a list.
>
> Running the code gives, for example:
> > e2 <- new.env(FALSE, NULL)
> > assign("dude", 123, env=e2)
> > assign("chick", 456, env=e2)
> > as.list(e2)
> Error in as.vector(x, "list") : cannot coerce to vector
>
> Is this the best way to make a list like this?
>
> Thanks,
> Ben
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