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How do I convert the y%m%d%H format into "%Y%m%d %H:%M:%S". My dates run from 1970 to 2010.

csgillespie
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user1537175
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    date <- strptime(Z$V1,format = "%y%m%d%H",tz = "GMT") – user1537175 Jul 23 '12 at 14:18
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    What you suggested above seems to work for me: as a tiny example (hint, see http://tinyurl.com/reproducible-000): `strptime("2012 5 10 13",format="%Y %m %d %H")` gives `[1] "2012-05-10 13:00:00"` – Ben Bolker Jul 23 '12 at 14:23
  • %Y%m%d%H with this format it works but format is %y%m%d%H example 00010100(2000010100) – user1537175 Jul 23 '12 at 14:32

2 Answers2

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Going partly from the comments (it would be nice if you could modify the question accordingly), it seems that this is not a case of formatting (%y vs %Y or spacing/delimiters), but of strptime/POSIX*t automatically setting the format to skip the hours/minutes/seconds when a 'midnight' time is specified. (This is my current guess based on the following examples, but I could have missed something.)

with %y, with non-midnight time:

> str(strptime("00020304",format="%y%m%d%H"))
 POSIXlt[1:1], format: "2000-02-03 04:00:00"

ditto, midnight time:

> str(strptime("00020300",format="%y%m%d%H"))
 POSIXlt[1:1], format: "2000-02-03"

midnight time (with spaces)

> str(strptime("00 02 03 00",format="%y %m %d %H"))
 POSIXlt[1:1], format: "2000-02-03"

a vector with one midnight and one non-midnight time:

> str(strptime(c("00020300","00020304"),format="%y%m%d%H"))
 POSIXlt[1:2], format: "2000-02-03 00:00:00" "2000-02-03 04:00:00"

So it looks like Dirk's answer is the way to go.

Ben Bolker
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2

Try this:

R> Sys.Date()
[1] "2012-07-23"
R> format(Sys.Date())
[1] "2012-07-23"
R> format(Sys.Date(), "%Y-%m-%d %H:%M:%S")
[1] "2012-07-23 00:00:00"
R>

as you probably have a Date type which, by definition, has no hour/minute/second information--use POSIXct for that. See help(DateTimeClasses) the details, and a bazillion posts here and on the various mailing lists with working examples.

Dirk Eddelbuettel
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  • %Y%m%d%H with this format it works but format is %y%m%d%H example 00010100(2000010100) – user1537175 Jul 23 '12 at 14:32
  • Based on my tests below it's not quite that the OP has a `Date` type, but rather than `POSIX*t` seems to set the format to skip H/M/S when it has a date at a midnight time. – Ben Bolker Jul 23 '12 at 15:21
  • That is possible too, but as he never told us via a reproducible example, we cannot really tell, can we? – Dirk Eddelbuettel Jul 23 '12 at 15:24
  • There are examples in the comments (if that counts). To the OP's credit (although it's not a well-written question), the fact that (it seems) `POSIX*t` sets a different format for vectors with all-midnight and some-non-midnight times is potentially confusing (and again IMHO) not a great default choice of behavior. – Ben Bolker Jul 23 '12 at 15:46