Re: [R] Simple as.Date question dealing with a timezone offset
Took me a minute to grok the gsubfn solution, but that is sweet! very nice. thank you very much both for the suggestions, Landon -- View this message in context: http://www.nabble.com/Simple-as.Date-question-dealing-with-a-timezone-offset-tp25491955p25512218.html Sent from the R help mailing list archive at Nabble.com. __ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
[R] Simple as.Date question dealing with a timezone offset
I've been trying to understand the as.Date functionality and I have a date and time stamp field that looks like this: Tue Sep 15 09:22:09 -0600 2009 and I need to turn it into an R Date object for analysis. Simple date conversions I have down, no problem: adate = c(7/30/1959) as.Date(adate,%m/%d/%Y) [1] 1959-07-30 But when it comes to the type of date/time string format I have above, I can't figure out a format string that will work. The timezone offset is one part that causes problems. Building up to a working format string for the full time stamp string, I can make it as far as: adate = c(Tue Sep 15 09:22:09 -0600 2009) as.Date(adate,format=%a %b %d %H:%M:%S) [1] 2009-09-15 (apparently year defaults to current year when it's not specified in the format string). Because the Year comes after the timezone offset, I have to deal with the timezone offset in the format string. But when I get to the timezone offset value I can't use %z or %Z because those are output only as.Date(adate,format=%a %b %d %H:%M:%S %z %Y) [1] NA I'm close, but can't incorporate the timezone offset field in the date/time stamp string. What am I missing? I suppose one workaround is to split the date/time string into its component parts, reassemble it into a string as.Date can deal with, but that seems to defeat one of the purposes of as.Date's format capability. Any advice for how to translate a Tue Sep 15 09:22:09 -0600 2009 into an R Date object? Landon -- View this message in context: http://www.nabble.com/Simple-as.Date-question-dealing-with-a-timezone-offset-tp25491955p25491955.html Sent from the R help mailing list archive at Nabble.com. __ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
Re: [R] Simple as.Date question dealing with a timezone offset
On Sep 17, 2009, at 11:25 AM, esawdust wrote: I've been trying to understand the as.Date functionality and I have a date and time stamp field that looks like this: Tue Sep 15 09:22:09 -0600 2009 and I need to turn it into an R Date object for analysis. Simple date conversions I have down, no problem: adate = c(7/30/1959) as.Date(adate,%m/%d/%Y) [1] 1959-07-30 But when it comes to the type of date/time string format I have above, I can't figure out a format string that will work. The timezone offset is one part that causes problems. Building up to a working format string for the full time stamp string, I can make it as far as: adate = c(Tue Sep 15 09:22:09 -0600 2009) as.Date(adate,format=%a %b %d %H:%M:%S) [1] 2009-09-15 (apparently year defaults to current year when it's not specified in the format string). Because the Year comes after the timezone offset, I have to deal with the timezone offset in the format string. But when I get to the timezone offset value I can't use %z or %Z because those are output only as.Date(adate,format=%a %b %d %H:%M:%S %z %Y) [1] NA You are confusing R Date objects with the the date-time classes. I don't think Date classes objects even allow TZ offets. ?DateTimeClasses as.POSIXct(as.Date(adate,%m/%d/%Y), origin=1960-01-01, tz=GMT) [1] 1959-07-29 20:00:00 EDT' Notice that my TZ (GMT -4) was used. so it was still the prior day in New England. I'm close, but can't incorporate the timezone offset field in the date/time stamp string. What am I missing? I suppose one workaround is to split the date/ time string into its component parts, reassemble it into a string as.Date can deal with, but that seems to defeat one of the purposes of as.Date's format capability. Any advice for how to translate a Tue Sep 15 09:22:09 -0600 2009 into an R Date object? Landon -- David Winsemius, MD Heritage Laboratories West Hartford, CT __ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
Re: [R] Simple as.Date question dealing with a timezone offset
Using strapply() from the gsubfn package, apply the
pattern (2nd arg) to string (1st arg). The matches
to the back references (i.e. the portions of the pattern
in parens) are passed to separate arguments of the
These arguments are date, offset and year respectively.
Then the function
calculates the appropriate date/time. (If you wanted
to ignore the offset or interpret it in some other way,
particularly in relation to time zones, then change the
function appropriately. Also the way its set up here it returns
a chron object since as.chron.POSIXt specifically
supports an offset= arg but you could change that.
Dealing with time zones is tricky and it wasn't clear
what you wanted precisely so you may have to fix
that up.)
library(gsubfn)
library(chron)
strapply(X = Tue Sep 15 09:22:09 -0600 2009,
pattern = (.*:..) ([-0-9]+) ([0-9]+)$,
FUN = function(date, offset, year) {
p - as.POSIXct(paste(date, year),
format = %a %b %d %H:%M:%S %Y)
as.chron(p, offset = as.numeric(offset))
},
simplify = c)
See R News 4/1 for info on dates and times and
http://gsubfn.googlecode.com for info on strapply.
On Thu, Sep 17, 2009 at 11:25 AM, esawdust lan...@360vl.com wrote:
I've been trying to understand the as.Date functionality and I have a date
and time stamp field that looks like this:
Tue Sep 15 09:22:09 -0600 2009
and I need to turn it into an R Date object for analysis.
Simple date conversions I have down, no problem:
adate = c(7/30/1959)
as.Date(adate,%m/%d/%Y)
[1] 1959-07-30
But when it comes to the type of date/time string format I have above, I
can't figure out a format string that will work.
The timezone offset is one part that causes problems. Building up to a
working format string for the full time stamp string, I can make it as far
as:
adate = c(Tue Sep 15 09:22:09 -0600 2009)
as.Date(adate,format=%a %b %d %H:%M:%S)
[1] 2009-09-15
(apparently year defaults to current year when it's not specified in the
format string). Because the Year comes after the timezone offset, I have to
deal with the timezone offset in the format string.
But when I get to the timezone offset value I can't use %z or %Z because
those are output only
as.Date(adate,format=%a %b %d %H:%M:%S %z %Y)
[1] NA
I'm close, but can't incorporate the timezone offset field in the date/time
stamp string.
What am I missing? I suppose one workaround is to split the date/time
string into its component parts, reassemble it into a string as.Date can
deal with, but that seems to defeat one of the purposes of as.Date's format
capability.
Any advice for how to translate a Tue Sep 15 09:22:09 -0600 2009 into an R
Date object?
Landon
--
View this message in context:
http://www.nabble.com/Simple-as.Date-question-dealing-with-a-timezone-offset-tp25491955p25491955.html
Sent from the R help mailing list archive at Nabble.com.
__
R-help@r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
__
R-help@r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
