Wrong length of POSIXt vectors (PR#10507)
On 12/11/2007 6:20 AM, simecek at gmail.com wrote:
Full_Name: Petr Simecek
Version: 2.5.1, 2.6.1
OS: Windows XP
Submission from: (NULL) (195.113.231.2)
Several times I have experienced that a length of a POSIXt vector has not been
computed right.
Example:
tv<-structure(list(sec = c(50, 0, 55, 12, 2, 0, 37, NA, 17, 3, 31
), min = c(1L, 10L, 11L, 15L, 16L, 18L, 18L, NA, 20L, 22L, 22L
), hour = c(12L, 12L, 12L, 12L, 12L, 12L, 12L, NA, 12L, 12L,
12L), mday = c(13L, 13L, 13L, 13L, 13L, 13L, 13L, NA, 13L, 13L,
13L), mon = c(5L, 5L, 5L, 5L, 5L, 5L, 5L, NA, 5L, 5L, 5L), year = c(105L,
105L, 105L, 105L, 105L, 105L, 105L, NA, 105L, 105L, 105L), wday = c(1L,
1L, 1L, 1L, 1L, 1L, 1L, NA, 1L, 1L, 1L), yday = c(163L, 163L,
163L, 163L, 163L, 163L, 163L, NA, 163L, 163L, 163L), isdst = c(1L,
1L, 1L, 1L, 1L, 1L, 1L, -1L, 1L, 1L, 1L)), .Names = c("sec",
"min", "hour", "mday", "mon", "year", "wday", "yday", "isdst"
), class = c("POSIXt", "POSIXlt"))
print(tv)
# print 11 time points (right)
length(tv)
# returns 9 (wrong)
tv is a list of length 9. The answer is right, your expectation is wrong.
I have tried that on several computers with/without switching to English
locales, i.e. Sys.setlocale("LC_TIME", "en"). I have searched a help pages but I
cannot imagine how that could be OK.
See this in ?POSIXt: Class '"POSIXlt"' is a named list of vectors... You could define your own length measurement as length.POSIXlt <- function(x) length(x$sec) and you'll get the answer you expect, but be aware that length.XXX methods are quite rare, and you may surprise some of your users. Duncan Murdoch