From tplate at acm.org  Tue Aug  4 20:26:14 2009
From: tplate at acm.org (Tony Plate)
Date: Tue, 04 Aug 2009 12:26:14 -0600
Subject: [Rd] can a key of a list be a variable
In-Reply-To: <e37a704c0908040947i40a02f9eg9bfa8b507ba0b9ef@mail.gmail.com>
References: <e37a704c0908040947i40a02f9eg9bfa8b507ba0b9ef@mail.gmail.com>
Message-ID: <4A787D46.6050207@acm.org>

Patterns like these can help to do what you want:

 > lapply(setNames(1:3, paste("step", 1:3, sep="")), function(i) seq(i))
$step1
[1] 1

$step2
[1] 1 2

$step3
[1] 1 2 3

 > setNames(list("the result"), paste("a", "name"))
$`a name`
[1] "the result"

 >

-- Tony Plate

Bilel MASMOUDI wrote:
> Hi,
>
> I search a solution to record data in dynamic structures in R.
> I have an algorithm that will be executed each step and whose output is an
> array of doubles with unknown size.
>
> The solution I found is to use lists
> 1) I initialise my list
>  l <- list()
> 2) and at a step numbered i I conacatain the new tab to the list
> vect <- algorithm()
> l <<--c( l , list(stepi=vect))
>
> The problem is that the key "stepi" is here a constant, I'd like to use a
> variable like this
> x = paste("step",index,sep="") where index is the last index (i)
> l <<--c( l , list(x=vect)) --> this doesn't function, the key is named "x"
> not "stepi"
> If I write l <<--c( l , list(paste("step",index,sep="") =vect)), I receive
> an error
>
> Many thanks for your help
>



[Rd] can a key of a list be a variable
Tony Plate