Gabor, thanks for the feedback. I like the idea of coercing the system time zone, and sticking with strptime/strftime. The balance would probably tip in favor of chron, however, if I could get the format correct. Apparently the default is two-digit year:
library(chron) chron(1) [1] 01/02/70 chron(1,format="m/d/y") [1] 01/02/70 But I need four digit year, so I try: chron(1,format="m/d/yyyy") [1] Jan/02/1970 Now, month has switched to character! I don't know of a format convention that gets it back to numeric (although conventions are documented for forcing to character). Comment? Regards, Tim. Gabor Grothendieck wrote: > If you use > > Sys.putenv(TZ = "GMT") > > at the beginning of your session then local time zone and GMT time > zone will be the same so you should not have a problem. This was > not possible, at least on Windows, at the time the R News article > was written. > > > > > > On 4/5/07, Tim Bergsma <[EMAIL PROTECTED]> wrote: >> Hi. >> >> I frequently convert date and time data to and from character >> representations. I'm frustrated with chron, because 'seconds' are >> required to create a time object (my input data never has seconds). > > You could use paste: > > times(paste("12:30", 0, sep = ":")) > > and make it into a function if you use it a lot. > >> More importantly, I cannot make chron print the format 12/30/2006 (which >> my output data requires). > > That is the default output format so you don't have to specify anything. > Its > only with POSIX that its not the default. For example: > >> library(chron) >> x <- chron("12/30/2006") >> x > [1] 12/30/06 > >> >> I really like the format flexibility of strftime() and strptime(), but >> of course am paranoid about timezone issues. After reading the standard >> reference several times >> (http://cran.r-project.org/doc/Rnews/Rnews_2004-1.pdf), I am tempted to >> conclude that if I never specify timezones, and never use Sys.time(), >> the vulnerabilities do not pertain. > > That won't protect you but this would let you use POSIX safely: > > http://www.mail-archive.com/r-help@stat.math.ethz.ch/msg83508.html > >> >> To the point: if I'm merely converting to and from character data that >> does not represent time zones, is there still a time zone vulnerability >> with strftime() and strptime()? >> >> Thanks in advance, >> >> Tim Bergsma, PhD >> Metrum Research Group, LLC >> >> >> #example >> strftime( >> strptime( >> "30-Dec-06 23:30", >> format="%d-%b-%y %H:%M" >> ), >> format="%m/%d/%Y %H:%M" >> ) >> [1] "12/30/2006 23:30" >> >> ______________________________________________ >> R-help@stat.math.ethz.ch 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@stat.math.ethz.ch 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.