R help - Jan 2011 - navigating in lists

Dear list members,


I am stuck with navigating in a rather complicated list object. 

In general I would need a solution to access all first (or other) elements of
the different sublists in one list:

test=list(a=list(1,2),b=list(3,4),c=list(5,6))

like:

test[[1:3]][[1]]

which should result in

c(1,3,5)


Is there any way to access lists in such a way? Using unlist would create quite
complicated objects....

Cheers
Jannis

> sapply(test, '[[', 1)
a b c 
1 3 5

-- 
Gregory (Greg) L. Snow Ph.D.
Statistical Data Center
Intermountain Healthcare
greg.snow at imail.org
801.408.8111

> -----Original Message-----
> From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-
> project.org] On Behalf Of Jannis
> Sent: Wednesday, January 12, 2011 1:50 PM
> To: r-help at r-project.org
> Subject: [R] navigating in lists
> 
> Dear list members,
> 
> 
> I am stuck with navigating in a rather complicated list object.
> 
> In general I would need a solution to access all first (or other)
> elements of the different sublists in one list:
> 
> test=list(a=list(1,2),b=list(3,4),c=list(5,6))
> 
> like:
> 
> test[[1:3]][[1]]
> 
> which should result in
> 
> c(1,3,5)
> 
> 
> Is there any way to access lists in such a way? Using unlist would
> create quite complicated objects....
> 
> Cheers
> Jannis
> 
> 
> 
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