>>>>> "l" == laurent <lgaut...@gmail.com> >>>>> on Sun, 09 Aug 2009 21:45:07 +0200 writes:
l> Thanks. It seems that the source of my confusion comes l> from using first using str() (and then once on the wrong l> track, it is easier to miss the information a man page l> that also describes POSIXct that is itself a vector of l> length equal to the number of entries it contains). l> With the current example: >> str(xd) l> POSIXlt[1:9], format: "2007-03-09" "2007-05-31" l> "2008-11-12" "2008-11-12" ... l> A quick inspection of the output does indicate a l> something with nine elements, but the elements appear to l> be "2007-03-09", "2007-05-31", etc... possibly creating l> confusion. l> To make it even more confusing I have: >> x[1] l> [1] "March 09, 2007" >> str(x[1]) l> chr "March 09, 2007" l> For what it is worth, I think that the behavior of the l> extract operator "[" (defined as a S3 method l> "[.POSIXlt()") is inconsistent with the output of l> length() (default method for lists). Yes, exactly; these two have beeb defined inconsistently, exactly in the respect you mention. Many months ago, when I came to the same conclusion, I vaguely remember that I had wanted / proposed to change this (namely, change [.POSIXlt, the length() method for "POSIXlt") , but IIRC had been vetoed by others. ... another frustrating experience for me ... Martin Maechler, ETH Zurich l> On Sun, 2009-08-09 at 11:45 -0500, Jeff Ryan wrote: >> The reason is in the ?strptime under value: >> >> 'strptime' turns character representations into an object of class >> '"POSIXlt"'. The timezone is used to set the 'isdst' component >> and to set the '"tzone"' attribute if 'tz != ""'. >> >> And POSIXlt is a list of length 9. >> >> >> HTH >> Jeff >> >> On Sun, Aug 9, 2009 at 10:35 AM, Gabor >> Grothendieck<ggrothendi...@gmail.com> wrote: >> > Try this to see its components: >> > >> >> str(unclass(xd)) >> > List of 9 >> > $ sec : num [1:6] 0 0 0 0 0 0 >> > $ min : int [1:6] 0 0 0 0 0 0 >> > $ hour : int [1:6] 0 0 0 0 0 0 >> > $ mday : int [1:6] 9 31 12 12 30 30 >> > $ mon : int [1:6] 2 4 10 10 6 6 >> > $ year : int [1:6] 107 107 108 108 109 109 >> > $ wday : int [1:6] 5 4 3 3 4 4 >> > $ yday : int [1:6] 67 150 316 316 210 210 >> > $ isdst: int [1:6] 0 1 0 0 1 1 >> > >> > and read R News 4/1 for more. >> > >> > On Sun, Aug 9, 2009 at 10:20 AM, laurent<lgaut...@gmail.com> wrote: >> >> Dear List, >> >> >> >> >> >> I am having an issue with strptime (see below). >> >> I can reproduce it on R-2.8, R-2.9, and R-2.10-dev, I tempted to see >> >> either a bug or my misunderstanding (and then I just don't currently see >> >> where). >> >> >> >> # setup: >> >> x <- c("March 09, 2007", "May 31, 2007", "November 12, 2008", "November >> >> 12, 2008", "July 30, 2009", "July 30, 2009" ) >> >> >> >> # showing the problem >> >>> length(x) >> >> 6 >> >>> xd <- strptime(x, format = "%B %d, %Y") >> >>> length(xd) >> >> 9 >> >>> xd[1:9] >> >> [1] "2007-03-09" "2007-05-31" "2008-11-12" "2008-11-12" "2009-07-30" >> >> [6] "2009-07-30" NA NA NA >> >>> length(strptime(rep(x, 2), format="%B %d, %Y")) >> >> [1] 9 >> >>> strptime(rep(x, 2), format="%B %d, %Y")[1:12] >> >> [1] "2007-03-09" "2007-05-31" "2008-11-12" "2008-11-12" "2009-07-30" >> >> [6] "2009-07-30" "2007-03-09" "2007-05-31" "2008-11-12" "2008-11-12" >> >> [11] "2009-07-30" "2009-07-30 >> >> >> >> Any pointer would be appreciated. >> >> >> >> L. ______________________________________________ R-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-devel