R help - Sep 2009 - extracting one element from all list elements

Hi

I have a list which cosists out of dataframes of the same structure. Now I
want to extract one column (let's say column "A") from all
dataframes and
have them in a matrix (or dataframe).

At the moment I am doiong:

d <- data.frame(A=runif(100), B=rnorm(100))
theList <- list(e1=d, e2=d, e3=d, e4=d)
f <- sapply(theList, function(l){l$A} )

But I am sure ther is a more elegant way?

Rainer

-- 
Rainer M. Krug, Centre of Excellence for Invasion Biology, Stellenbosch
University, South Africa

	[[alternative HTML version deleted]]

Try this:

 sapply(theList, '[[', 'A')

On Wed, Sep 16, 2009 at 8:34 AM, Rainer M Krug <r.m.krug at gmail.com>
wrote:
> Hi
>
> I have a list which cosists out of dataframes of the same structure. Now I
> want to extract one column (let's say column "A") from all
dataframes and
> have them in a matrix (or dataframe).
>
> At the moment I am doiong:
>
> d <- data.frame(A=runif(100), B=rnorm(100))
> theList <- list(e1=d, e2=d, e3=d, e4=d)
> f <- sapply(theList, function(l){l$A} )
>
> But I am sure ther is a more elegant way?
>
> Rainer
>
> --
> Rainer M. Krug, Centre of Excellence for Invasion Biology, Stellenbosch
> University, South Africa
>
> ? ? ? ?[[alternative HTML version deleted]]
>
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>


-- 
Henrique Dallazuanna
Curitiba-Paran?-Brasil
25? 25' 40" S 49? 16' 22" O