[R] timeDate

Tue Nov 23 16:39:04 CET 2004

You might want to check out 'chron'.  This stores the time as days and
fractions of a day.

If you take the current date,

> as.numeric(chron(dates.="11/23/2004"))
[1] 12745
>

you get the value above.  If you change this to millisecond, you get

> as.numeric(chron(dates.="11/23/2004")) * 86400 * 1000
[1] 1.101168e+12
>

this value requires 46 bits and since a floating point number has 54 bits
of value, it should be enough to give you millisecond resolution and still
maintain the 'date'
__________________________________________________________
James Holtman        "What is the problem you are trying to solve?"
Executive Technical Consultant  --  Office of Technology, Convergys
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                      Yasser El-Zein                                                                                                       
                      <abu3ammar at gmail.com>        To:       r-help at stat.math.ethz.ch                                                      
                      Sent by:                     cc:                                                                                     
                      r-help-bounces at stat.m        Subject:  Re: [R] timeDate                                                              
                      ath.ethz.ch                                                                                                          

                      11/23/2004 09:55                                                                                                     
                      Please respond to                                                                                                    
                      Yasser El-Zein                                                                                                       

I am looking for up to the millisecond resolution. Is there a package
that has that?

On Mon, 22 Nov 2004 21:48:20 +0000 (UTC), Gabor Grothendieck
<ggrothendieck at myway.com> wrote:
> Yasser El-Zein <abu3ammar <at> gmail.com> writes:
>
> >
> > >From the document it is apparent to me that I need as.POSIXct  (I have
> > a double representing the number of millis since 1/1/1970 and I need
> > to construct a datetime object). I see it showing how to construct the
> > time object from a string representing the time but now fro a double
> > of millis. Does anyone know hoe to do that?
> >
>
> If by millis you mean milliseconds (i.e. one thousandths of a second)
> then POSIXct does not support that resolution, but if rounding to
> seconds is ok then
>
>   structure(round(x/1000), class = c("POSIXt", "POSIXct"))
>
> should give it to you assuming x is the number of milliseconds.
>
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