R help - Nov 2010 - slicing list with matrices

A list contains several matrices. Over all matrices (list elements) I'd like
to access one matrix cell:

m <- matrix(1:9, nrow=3, dimnames=list(LETTERS[1:3], letters[1:3]))
l <- list(m1=m, m2=m*2, m3=m*3)
l[[3]] # works
l[[3]][1:2, ] # works
l[[1:3]][1, 1] # does not work

How can I slice all C-c combinations in the list?

S?ren

-- 
S?ren Vogel, Dipl.-Psych. (Univ.), PhD-Student, Eawag, Dept. SIAM
+41 76 233 3637, http://www.eawag.ch, http://sozmod.eawag.ch

try this:

m <- matrix(1:9, nrow=3, dimnames=list(LETTERS[1:3], letters[1:3]))
l <- list(m1=m, m2=m*2, m3=m*3)

lapply(l, "[", 1, 1)

# or

sapply(l, "[", 1, 1)


I hope it helps.

Best,
Dimitris


On 11/17/2010 3:01 PM, soeren.vogel at eawag.ch wrote:
> A list contains several matrices. Over all matrices (list elements) I'd
like to access one matrix cell:
>
> m<- matrix(1:9, nrow=3, dimnames=list(LETTERS[1:3], letters[1:3]))
> l<- list(m1=m, m2=m*2, m3=m*3)
> l[[3]] # works
> l[[3]][1:2, ] # works
> l[[1:3]][1, 1] # does not work
>
> How can I slice all C-c combinations in the list?
>
> S?ren
>
-- 
Dimitris Rizopoulos
Assistant Professor
Department of Biostatistics
Erasmus University Medical Center

Address: PO Box 2040, 3000 CA Rotterdam, the Netherlands
Tel: +31/(0)10/7043478
Fax: +31/(0)10/7043014
Web: http://www.erasmusmc.nl/biostatistiek/

Maybe 

	lapply(l,function(x){x[1,1]})
or
	unlist(lapply(l,function(x){x[1,1]})) 

does what you want?

	Benno 

Am 17.Nov.2010 um 15:01 schrieb soeren.vogel at eawag.ch:
> m <- matrix(1:9, nrow=3, dimnames=list(LETTERS[1:3], letters[1:3]))
> l <- list(m1=m, m2=m*2, m3=m*3)
> l[[3]] # works
> l[[3]][1:2, ] # works
> l[[1:3]][1, 1] # does not work