[R] Question on creating Date variable

[Christofer Bogaso]

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.

Thanks and regards,