[R] Format about Date and time

[David Winsemius]

On Mar 14, 2009, at 8:52 AM, Aimin Yan wrote:

> I have a data set like this:
>
> > head(FormatedData)
>    ID Target Actual     Date     Time
> 1 2030      0  -57.0 12/20/08 17:03:00
> 2 2030     90   90.0 12/20/08 18:41:00
> 3 2030     45   43.8 12/21/08 14:36:00
> 4 2030      0  -23.8 12/21/08 19:30:00
> 5 2030     90   90.2 12/21/08 21:48:00
> 6 2030     45   48.6 12/22/08 13:02:00
>
> I wan to convert the format of Date and Time, so I did this:
>
> pdate <- as.POSIXct(strptime(FormatedData$Date,"%m/%d/%Y"))

You do not have a %Y format for years.

See if this minimal example helps::
timedf <- data.frame(Date1 = "12/20/08", Time1= "17:03:00")
strptime( with(timedf, paste(Date1,Time1) ), format="%m/%d/%y %H:%M:%S")
# [1] "2008-12-20 17:03:00"

>
> ptime <- as.POSIXct(strptime(FormatedData$Time,"%H:%M:%S"))
>
> but I get the following format:
>
> > head(NewFormatedData)
>    ID Target Actual     Date     Time   pdate               ptime
> 1 2030      0  -57.0 12/20/08 17:03:00 8-12-20 2009-03-14 17:03:00
> 2 2030     90   90.0 12/20/08 18:41:00 8-12-20 2009-03-14 18:41:00
> 3 2030     45   43.8 12/21/08 14:36:00 8-12-21 2009-03-14 14:36:00
> 4 2030      0  -23.8 12/21/08 19:30:00 8-12-21 2009-03-14 19:30:00
> 5 2030     90   90.2 12/21/08 21:48:00 8-12-21 2009-03-14 21:48:00
> 6 2030     45   48.6 12/22/08 13:02:00 8-12-22 2009-03-14 13:02:00
>
> in ptime, it includes the current date, I don't want this,
> actually, I want to have the following formats:
>
>    ID Target Actual     Date     Time    pdate               ptime
> 1 2030      0  -57.0 12/20/08 17:03:00  2008-12-20      17:03:00
> 2 2030     90   90.0 12/20/08 18:41:00 2008-12-20      18:41:00
> 3 2030     45   43.8 12/21/08 14:36:00  2008-12-21     14:36:00
> 4 2030      0  -23.8 12/21/08 19:30:00   2008-12-21     19:30:00
> 5 2030     90   90.2 12/21/08 21:48:00  2008-12-21      21:48:00
> 6 2030     45   48.6 12/22/08 13:02:00  2008-12-22     13:02:00
>
> Does anyone know how to do these?
>

David Winsemius, MD
Heritage Laboratories
West Hartford, CT