[R] extracting elements from a list in vectorized form

From: <jgarcia_at_ija.csic.es>
Date: Tue, 01 Jul 2008 09:40:33 +0200 (CEST)


Hi;
It seems to me that has probably been asked in the past. But I cannot find the track.

I usually need to extract elements from a list and contruct vector from them; e.g., to create a table. Perhaps there is a way to directly extract them without looping?
Simple example:

> S.lst
$sublist.1
$sublist.1$age

[1] 24.58719

$sublist.1$weight

[1] 60.82861

$sublist.2
$sublist.2$age

[1] 32.39551

$sublist.2$weight

[1] 59.46347

etc.

I would like to extract, e.g., directly all weights element from each sublist without looping. I know it is possible to do this as:

unlist(S.lst)[paste("sublist.",1:length(S.lst),".weight",sep="")]

but there is not some short-cut? something like

S.lst[[1:length(S.lst)]]$weight ?

Thanks and B.regards

Javier




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