[R] Question on creating Date variable

[David L Carlson]

Try this (assuming 14.75 is hours/decimal hours, i.e. 14:45):

> x <- scan(text = "11.00 11.25 11.35 12.01 11.14 13.00 13.25 13.35 14.01 
+  13.14 14.50 14.75 14.85 15.51 14.64 ")
Read 15 items
> x
 [1] 11.00 11.25 11.35 12.01 11.14 13.00 13.25 13.35 14.01 13.14 14.50 14.75
[13] 14.85 15.51 14.64
> y <- as.POSIXct(paste( floor(x), round(60*(x-floor(x))) ), format="%H %M")
> y
 [1] "2012-12-31 11:00:00 CST" "2012-12-31 11:15:00 CST"
 [3] "2012-12-31 11:21:00 CST" "2012-12-31 12:01:00 CST"
 [5] "2012-12-31 11:08:00 CST" "2012-12-31 13:00:00 CST"
 [7] "2012-12-31 13:15:00 CST" "2012-12-31 13:21:00 CST"
 [9] "2012-12-31 14:01:00 CST" "2012-12-31 13:08:00 CST"
[11] "2012-12-31 14:30:00 CST" "2012-12-31 14:45:00 CST"
[13] "2012-12-31 14:51:00 CST" "2012-12-31 15:31:00 CST"
[15] "2012-12-31 14:38:00 CST"
> format(y, format="%Y-%m-%d %I:%M %p")
 [1] "2012-12-31 11:00 AM" "2012-12-31 11:15 AM" "2012-12-31 11:21 AM"
 [4] "2012-12-31 12:01 PM" "2012-12-31 11:08 AM" "2012-12-31 01:00 PM"
 [7] "2012-12-31 01:15 PM" "2012-12-31 01:21 PM" "2012-12-31 02:01 PM"
[10] "2012-12-31 01:08 PM" "2012-12-31 02:30 PM" "2012-12-31 02:45 PM"
[13] "2012-12-31 02:51 PM" "2012-12-31 03:31 PM" "2012-12-31 02:38 PM"

----------------------------------------------
David L Carlson
Associate Professor of Anthropology
Texas A&M University
College Station, TX 77843-4352


> -----Original Message-----
> From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-
> project.org] On Behalf Of David Winsemius
> Sent: Monday, December 31, 2012 1:58 PM
> To: Christofer Bogaso
> Cc: r-help at r-project.org
> Subject: Re: [R] Question on creating Date variable
> 
> 
> On Dec 31, 2012, at 11:54 AM, Christofer Bogaso wrote:
> 
> > On 01 January 2013 01:29:53, David Winsemius wrote:
> >>
> >> On Dec 31, 2012, at 11:35 AM, Christofer Bogaso wrote:
> >>
> >>> On 01 January 2013 00:17:50, David Winsemius wrote:
> >>>>
> >>>> On Dec 31, 2012, at 9:12 AM, Christofer Bogaso wrote:
> >>>>
> >>>>> Hello all,
> >>>>>
> >>>>> Let say I have following (numeric) vector:
> >>>>>
> >>>>> > x
> >>>>> [1] 11.00 11.25 11.35 12.01 11.14 13.00 13.25 13.35 14.01 13.14
> >>>>> 14.50
> >>>>> 14.75 14.85 15.51 14.64
> >>>>>
> >>>>> Now, I want to create a 'Date' variable (i.e. I should be able
> >>>>> to do
> >>>>> all calculations pertaining to date/time and also time-series
> >>>>> plotting etc.) like
> >>>>>
> >>>>> 2012-12-31 11:00:00 AM, 2012-12-31 11:25:00 AM, 2012-12-31
> >>>>> 11:35:00
> >>>>> AM, 2012-12-31 12:01:00 PM, . . . .
> >>>>>
> >>>>
> >>>> Those _times_ ( _not_ Dates) cannot possibly be in %M.%S" format,
> >>>> given the number of items to the right of the decimal point that
> >>>> are
> >>>> greater than 60. So will proceed on the arguably more likely
> >>>> assumption that they are in fractional minutes. To recover from
> >>>> that
> >>>> problem, one might consider:
> >>>>
> >>>> > as.POSIXct(paste( floor(x), round(60*(x-floor(x))) ),
> >>>> format="%M %S")
> >>>> [1] "2012-12-31 00:11:00 PST" "2012-12-31 00:11:15 PST"
> >>>> [3] "2012-12-31 00:11:21 PST" "2012-12-31 00:12:01 PST"
> >>>> [5] "2012-12-31 00:11:08 PST" "2012-12-31 00:13:00 PST"
> >>>> [7] "2012-12-31 00:13:15 PST" "2012-12-31 00:13:21 PST"
> >>>> [9] "2012-12-31 00:14:01 PST" "2012-12-31 00:13:08 PST"
> >>>> [11] "2012-12-31 00:14:30 PST" "2012-12-31 00:14:45 PST"
> >>>> [13] "2012-12-31 00:14:51 PST" "2012-12-31 00:15:31 PST"
> >>>> [15] "2012-12-31 00:14:38 PST"
> >>>>
> >>>
> >>> I understand that some of those elements are not "dates". However
> >>> what I want is the ***"PM/AM" suffix*** on those elements which are
> >>> considered as Dates.
> >>>
> >>> ***Getting those suffix*** and doing calculations on those changed
> >>> variables is my primary concern.
> >>
> >> That's the first time that AM/PM has bee mentioned and I suppose if
> >> those were fractional hours rather than my guess of fractional
> >> minutes
> >> that there might be representatives of both in the numeric data you
> >> offered. Why don't you clarify what these number do in fact
> >> represent?
> >> And what problem you are trying to solve?
> >>
> >
> > Basically those are artificial data! Actually I do not have the
> > right to give out the original data in any public forum. So I
> > created those artificial data so that I can get the fundamental
> > idea ...........
> >
> > Each element (assuming they are legitimate time) represents the time
> > for a particular day when some event is pop-up. like, 11AM, 11.30AM,
> > 12.05PM etc.. I could work with something like 11.00, 11.30, 12.05,
> > 15.00 etc. however I believe adding AM/PM suffice will make my
> > report more eye-catching.
> >
> > Please let me know if you need more clarification.
> 
> So what's with the values above 59 in the minutes?
> 
> 
> >
> >
> > Thanks and regards,
> 
> David Winsemius, MD
> Alameda, CA, USA
> 
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