Description

Details

R excels at computing with dates, and times. Using typed representation for your data is highly recommended not only because of the functionality offered but also because of the added safety stemming from proper representation.

But there is a small nuisance cost in interactive work as well as in programming. How often have we told as.POSIXct() that the origin is (of course) the epoch. Do we really have to say it again? Similarly, when parsing dates that are somewhat in YYYYMMDD format, do we really need to bother converting from integer or numeric or character or factor or ordered with one of dozen separators and/or month forms: YYYY-MM-DD, YYYY/MM/DD, YYYYMMDD, YYYY-mon-DD and so on?

So there may have been a need for a general purpose converter returning a proper POSIXct (or Date) object no matter the input (provided it was somewhat parseable). anytime() tries to be that function.

The actual conversion is done by a combination of Boost lexical_cast to go from (almost) anything to string representation which is then parsed by Boost Date_Time. An alternate method using the corresponding R functions is also available as a fallback.

Conversion is done by looping over a fixed set of formats until a matching one is found, or returning an error if none is found. The current set of conversion formulae is accessible in the source code, and can now also be accessed in R via getFormats(). Formats can be added and removed via the addFormats() and removeFormats{} functions.

Details on the Boost date format symbols are provided by the Boost date_time documentation and similar (but not identical) to what strftime uses.

Author(s)

References

Boost date_time: https://www.boost.org/doc/libs/1_70_0/doc/html/date_time.html

Formats used: https://github.com/eddelbuettel/anytime/blob/master/src/anytime.cpp#L43-L106

Boost format documentation: https://www.boost.org/doc/libs/1_61_0/doc/html/date_time/date_time_io.html#date_time.format_flags

Examples

library("anytime")

  Sys.setenv(TZ=anytime:::getTZ())      ## helper function to try to get TZ
  options(digits.secs=6)                ## for fractional seconds below

  library(anytime)                      ## load package, caches TZ information

  ## integer
  anydate(20160101L + 0:2)

[1] "2016-01-01" "2016-01-02" "2016-01-03"

  ## numeric
  anydate(20160101 + 0:2)

[1] "2016-01-01" "2016-01-02" "2016-01-03"

  ## factor
  anydate(as.factor(20160101 + 0:2))

[1] "2016-01-01" "2016-01-02" "2016-01-03"

  ## ordered
  anydate(as.ordered(20160101 + 0:2))

[1] "2016-01-01" "2016-01-02" "2016-01-03"

  ## Dates: Character
  anydate(as.character(20160101 + 0:2))

[1] "2016-01-01" "2016-01-02" "2016-01-03"

  ## Dates: alternate formats
  anydate(c("20160101", "2016/01/02", "2016-01-03"))

[1] "2016-01-01" "2016-01-02" "2016-01-03"

  ## Datetime: ISO with/without fractional seconds
  anytime(c("2016-01-01 10:11:12", "2016-01-01 10:11:12.345678"))

[1] "2016-01-01 10:11:12.000000 UTC" "2016-01-01 10:11:12.345678 UTC"

  ## Datetime: ISO alternate (?) with 'T' separator
  anytime(c("20160101T101112", "20160101T101112.345678"))

[1] "2016-01-01 UTC" "2016-01-01 UTC"

  ## Short month '%b' (and full month is supported too)
  anytime(c("2016-Sep-01 10:11:12", "Sep/01/2016 10:11:12", "Sep-01-2016 10:11:12"))

[1] "2016-09-01 10:11:12 UTC" "2016-09-01 10:11:12 UTC"
[3] "2016-09-01 10:11:12 UTC"

  ## Datetime: Mixed format (cf https://stackoverflow.com/questions/39259184)
  anytime(c("Thu Sep 01 10:11:12 2016", "Thu Sep 01 10:11:12.345678 2016"))

[1] "2016-09-01 10:11:12.000000 UTC" "2016-09-01 10:11:12.345678 UTC"