R help - Feb 2014 - why is as.date function not working for me? (dd/mm/yyyy h:mm)

Why am I know getting hours after I convert the date?

 dates <- c('31/12/2013 0:00',  '31/12/2013 1:00', 
'31/12/2013 2:00',
'31/12/2013 3:00',  '31/12/2013 4:00',  '31/12/2013
5:00',  '31/12/2013
6:00',  '31/12/2013 7:00',  '31/12/2013 8:00', 
'31/12/2013 9:00',
'31/12/2013 10:00', '31/12/2013 11:00',  '31/12/2013
12:00', '31/12/2013
13:00', '31/12/2013 14:00', '31/12/2013 15:00', 
'31/12/2013 16:00',
'31/12/2013 17:00', '31/12/2013 18:00', '31/12/2013
19:00', '31/12/2013
20:00', '31/12/2013 21:00', '31/12/2013 22:00',
'31/12/2013 23:00',
'01/01/2014 0:00')

as.Date(dates, format="%d/%m/%Y %H:%M")
 [1] "2013-12-31" "2013-12-31" "2013-12-31"
"2013-12-31" "2013-12-31"
 [6] "2013-12-31" "2013-12-31" "2013-12-31"
"2013-12-31" "2013-12-31"
[11] "2013-12-31" "2013-12-31" "2013-12-31"
"2013-12-31" "2013-12-31"
[16] "2013-12-31" "2013-12-31" "2013-12-31"
"2013-12-31" "2013-12-31"
[21] "2013-12-31" "2013-12-31" "2013-12-31"
"2013-12-31" "2014-01-01"





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as.Date produces Dates only, with no time information, even if you try
to supply it with hours + minutes.

For dates+times, use as.POSIXct() or as.POSIXlt() in place of
as.Date(). POSIXct produces a numeric value for the number of seconds
since your specified origin time (usually 1970-01-01 00:00), and
POSIXlt produces a list object with individual entries for year,
month, day, hour, minute etc. Be aware that time zones and daylight
savings transitions may suddenly come into play. See ?DateTimeClasses
for the gory details.

as.POSIXct(dates, format = "%d/%m/%Y %H:%M")


On Thu, Feb 6, 2014 at 10:24 AM, jcrosbie <james at crosb.ie>
wrote:
> Why am I know getting hours after I convert the date?
>
>  dates <- c('31/12/2013 0:00',  '31/12/2013 1:00', 
'31/12/2013 2:00',
> '31/12/2013 3:00',  '31/12/2013 4:00',  '31/12/2013
5:00',  '31/12/2013
> 6:00',  '31/12/2013 7:00',  '31/12/2013 8:00', 
'31/12/2013 9:00',
> '31/12/2013 10:00', '31/12/2013 11:00',  '31/12/2013
12:00', '31/12/2013
> 13:00', '31/12/2013 14:00', '31/12/2013 15:00', 
'31/12/2013 16:00',
> '31/12/2013 17:00', '31/12/2013 18:00', '31/12/2013
19:00', '31/12/2013
> 20:00', '31/12/2013 21:00', '31/12/2013 22:00',
'31/12/2013 23:00',
> '01/01/2014 0:00')
>
> as.Date(dates, format="%d/%m/%Y %H:%M")
>  [1] "2013-12-31" "2013-12-31" "2013-12-31"
"2013-12-31" "2013-12-31"
>  [6] "2013-12-31" "2013-12-31" "2013-12-31"
"2013-12-31" "2013-12-31"
> [11] "2013-12-31" "2013-12-31" "2013-12-31"
"2013-12-31" "2013-12-31"
> [16] "2013-12-31" "2013-12-31" "2013-12-31"
"2013-12-31" "2013-12-31"
> [21] "2013-12-31" "2013-12-31" "2013-12-31"
"2013-12-31" "2014-01-01"
>
>
>
>
>
> --
> View this message in context:
http://r.789695.n4.nabble.com/why-is-as-date-function-not-working-for-me-dd-mm-yyyy-h-mm-tp4684874.html
> Sent from the R help mailing list archive at Nabble.com.
>
> ______________________________________________
> R-help at r-project.org 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.

Because a Date object represents calendar dates, and calendar dates don't
have hours.

Use as.POSIXct() instead of as.Date()
(and spend a little more time with the documentation for as.Date)

-Don

-- 
Don MacQueen

Lawrence Livermore National Laboratory
7000 East Ave., L-627
Livermore, CA 94550
925-423-1062





On 2/6/14 10:24 AM, "jcrosbie" <james at crosb.ie> wrote:
>Why am I know getting hours after I convert the date?
>
> dates <- c('31/12/2013 0:00',  '31/12/2013 1:00', 
'31/12/2013 2:00',
>'31/12/2013 3:00',  '31/12/2013 4:00',  '31/12/2013
5:00',  '31/12/2013
>6:00',  '31/12/2013 7:00',  '31/12/2013 8:00', 
'31/12/2013 9:00',
>'31/12/2013 10:00', '31/12/2013 11:00',  '31/12/2013
12:00', '31/12/2013
>13:00', '31/12/2013 14:00', '31/12/2013 15:00', 
'31/12/2013 16:00',
>'31/12/2013 17:00', '31/12/2013 18:00', '31/12/2013
19:00', '31/12/2013
>20:00', '31/12/2013 21:00', '31/12/2013 22:00',
'31/12/2013 23:00',
>'01/01/2014 0:00')
>
>as.Date(dates, format="%d/%m/%Y %H:%M")
> [1] "2013-12-31" "2013-12-31" "2013-12-31"
"2013-12-31" "2013-12-31"
> [6] "2013-12-31" "2013-12-31" "2013-12-31"
"2013-12-31" "2013-12-31"
>[11] "2013-12-31" "2013-12-31" "2013-12-31"
"2013-12-31" "2013-12-31"
>[16] "2013-12-31" "2013-12-31" "2013-12-31"
"2013-12-31" "2013-12-31"
>[21] "2013-12-31" "2013-12-31" "2013-12-31"
"2013-12-31" "2014-01-01"
>
>
>
>
>
>--
>View this message in context:
>http://r.789695.n4.nabble.com/why-is-as-date-function-not-working-for-me-d
>d-mm-yyyy-h-mm-tp4684874.html
>Sent from the R help mailing list archive at Nabble.com.
>
>______________________________________________
>R-help at r-project.org 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.