Hi,
Perhaps Hadley's plyr package can help,
library(plyr)
temp <- list(x=2,y=3,x=4)
llply(temp, function(x) x^2 )
$x
[1] 4
$y
[1] 9
$x
[1] 16
baptiste
On 27 Feb 2009, at 03:07, Alexy Khrabrov wrote:
Sometimes I'm iterating over a list where names are keys into another
data structure, e.g. a related list. Then I can't use lapply as it
does [[]] and loses the name. Then I do something like this:
do.one <- function(ldf) { # list-dataframe item
key <- names(ldf)
meat <- ldf[[1]]
mydf <- some.df[[key]] # related data structure
r.df <- cbind(meat,new.column=computed)
r <- list(xxx=r.df)
names(r) <- key
r
}
then if I operate on the list L of those ldf's not as lapply(L,...),
but
res <- lapply(1:length(L),do.one)
Can this procedure be simplified so that names are preserved?
Specifically, can the xxx=..., xxx <- key part be eliminated -- how
can we have a variable on the left-hand side of list(lhs=value)?
Cheers,
Alexy
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_____________________________
Baptiste Auguié
School of Physics
University of Exeter
Stocker Road,
Exeter, Devon,
EX4 4QL, UK
Phone: +44 1392 264187
http://newton.ex.ac.uk/research/emag
______________________________________________
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PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
