library(plyr)
ldply(x,function(v){data.frame(Start=v$Start,End=v$End)})
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Jeff Newmiller The ..... ..... Go Live...
DCN:<jdnew...@dcn.davis.ca.us> Basics: ##.#. ##.#. Live Go...
Live: OO#.. Dead: OO#.. Playing
Research Engineer (Solar/Batteries O.O#. #.O#. with
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Sent from my phone. Please excuse my brevity.
Kenn Konstabel <lebats...@gmail.com> wrote:
Dear all, I am working with a list of objects each of which contains two
POSIXct objects (say, $Start and $End) and a number of different data in
addition to that. Now an easy way to extract Start times of all object could be
sapply(x, "[", "Start") but this converts them all to numeric, and so does
sapply(x, "[[", "Start"). lapply preserves the class but is obviously a list
rather than an atomic vector but using unlist is a way of getting rid of the
class again. I know the vector can be converted back using as.POSIXct and that
one can set the class attribute back to "POSIXct" but is there an easier trick
that I can't just figure out? Thanks in advance for any suggestions. A
reproducible example: foo <- as.list(Sys.time()+1:10) sapply(foo, "[", 1) I've
also noticed that trunc.POSIXt does something unexpected (to me) in some cases:
foo <- as.POSIXct("2011-03-25 21:03:20")+1:10 length(foo) ## obviously 10
length(trunc(foo, "day")) # 1! This makes it impossible to use [ and leng
th()
with trunc'ed POSIXct vectors (and it is a little unexpected too that the
result of using trunc with a POSIX_ct_ object is a POSIX_lt_ object) but the
cure seems easy: in the code of [.POSIXt, ## old ## new x$sec <- 0 ## x$sec[]
<- 0 x$min <- 0L ## x$min[] <- 0L x$hour <- 0L ## x$hour[] <- 0L After these
changes, [ and length would work "correctly" (in my possibly naive
understanding), and length(trunc(foo, "day")) would return 10 in the example
above. Best regards, Kenn Kenn Konstabel National Institute for Health
Development Hiiu 42 Tallinn Estonia_____________________________________________
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