indexing a particular element in a list of vectors
Or
do.call("cbind",x)[1,]
which of course makes a whole new copy of x and
gives you a nasty warning as well, but does not
use a conceptual `for` loop. Which I think was the
original question, to which AFAIK the answer is no, there is no
easy subscripting construct such as x[[1:3]][1] that will do
what was asked.
-----Original Message----- From: Peter Dalgaard [mailto:p.dalgaard at biostat.ku.dk] Sent: 17 October 2003 08:48 To: Richard A. O'Keefe Cc: nortonsm at verizon.net; r-help at stat.math.ethz.ch Subject: Re: [R] indexing a particular element in a list of vectors Security Warning: If you are not sure an attachment is safe to open please contact Andy on x234. There are 0 attachments with this message.
________________________________________________________________
"Richard A. O'Keefe" <ok at cs.otago.ac.nz> writes:
"Scott Norton" <nortonsm at verizon.net> wrote:
I have a "list" of character vectors. I'm trying to see if
there is a way (in a single line, without a loop) to pull out
the first element of all the vectors contained in the list.
You have a list.
You want to do something to each element.
See ?lapply
u <- c("Fee","fie","foe","fum")
v <- c("Ping","pong","diplomacy")
w <- c("Hi","fi")
x <- list(a=u, b=v, c=w)
lapply(x, function (cv) cv[1])
...
If you want the result as a character vector, see ?sapply
sapply(x, function (cv) cv[1])
a b c
"Fee" "Ping" "Hi"
Or even
sapply(x, "[", 1)
a b c
"Fee" "Ping" "Hi"
(same thing with lapply)
--
O__ ---- Peter Dalgaard Blegdamsvej 3
c/ /'_ --- Dept. of Biostatistics 2200 Cph. N
(*) \(*) -- University of Copenhagen Denmark Ph:
(+45) 35327918
~~~~~~~~~~ - (p.dalgaard at biostat.ku.dk) FAX:
(+45) 35327907
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