[R] generated list element names

[William Dunlap]

If you have a list and want to add a new (or replace a)
named component use
   myList[[compName]] <- compValue
as in
   myList <- list()
   compName <- "Incr"
   compValue <- function(x) x + 1
   myList[[compName]] <- compValue

If you want to make a new list-with-names from scratch try
   structure(list(1, "cat", function(x)x+1), names=c("One","Pet","Increment"))
(structure() is a general way to make an object and add attributes to
it in one statement.)

Bill Dunlap
Spotfire, TIBCO Software
wdunlap tibco.com


> -----Original Message-----
> From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-project.org] On Behalf
> Of Sam Steingold
> Sent: Monday, November 19, 2012 10:07 AM
> To: r-help at r-project.org
> Subject: [R] generated list element names
> 
> How can I create lists with element names created on the fly?
> 
> --8<---------------cut here---------------start------------->8---
> > list (foo = 10)
> $foo
> [1] 10
> 
> > list ("foo" = 10)
> $foo
> [1] 10
> 
> > list (paste("f","oo",sep="") = 10)
> Error: unexpected '=' in "list (paste("f","oo",sep="") ="
> --8<---------------cut here---------------end--------------->8---
> 
> I understand that tags in list() are not evaluated, but is there a more
> elegant way than
> 
> --8<---------------cut here---------------start------------->8---
> > z <- list(10)
> > names(z) <- paste("f","oo",sep="")
> > z
> $foo
> [1] 10
> --8<---------------cut here---------------end--------------->8---
> 
> thanks!
> 
> --
> Sam Steingold (http://sds.podval.org/) on Ubuntu 12.04 (precise) X 11.0.11103000
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