Re: [Rd] chron vs. POSIX

From: Gabor Grothendieck <>
Date: Sat 15 Jul 2006 - 22:14:35 GMT

On 7/15/06, Duncan Murdoch <> wrote:
> On 7/15/2006 1:37 PM, Gabor Grothendieck wrote:
> > On 7/15/06, Duncan Murdoch <> wrote:
> >> On 7/15/2006 1:01 PM, Gabor Grothendieck wrote:
> >>> On 7/14/06, Duncan Murdoch <> wrote:
> >>>> On 7/14/2006 3:38 PM, Sebastian Luque wrote:
> >>>>> Hi,
> >>>>>
> >>>>> One of the big decisions when writing code is how to handle dates and
> >>>>> times. Gabor Grothendieck provided an excellent overview of the issue in
> >>>>> his R News 4/1 (2004) article, and many users and developers are probably
> >>>>> using it as a guide. The proposed guideline is to use the simplest class
> >>>>> required; as Gabor put it "use Date if possible, otherwise use chron, and
> >>>>> otherwise use POSIX".
> >>>>>
> >>>>> This seems to me a very efficient strategy, judging from my own
> >>>>> experiences and those of others users. All but the simplest calculations
> >>>>> with POSIX objects demand great care, due to time zone and and daylight
> >>>>> savings considerations. Therefore, I've always chosen chron for
> >>>>> relatively complex projects, where I don't need to deal with time zones or
> >>>>> daylight savings problems. The ease with which objects can be switched
> >>>>> from numeric to chron representations is a major advantage IMHO¹.
> >>>>>
> >>>>> If Gabor's recommendations are to be followed, wouldn't it make sense to
> >>>>> include chron in base R? Given that flexibility for handling time
> >>>>> variables is so fundamental, the addition of chron to base R would provide
> >>>>> users everything they need to work with time, without the need to rely on
> >>>>> an external package. What do others think?
> >>>> Putting something into base R essentially means that it is to be taken
> >>>> over by R core. I think chron is being adequately maintained now (the R
> >>>> maintainer is already a member of R core), so I don't see a need for that.
> >>>>
> >>>> I don't see a problem having a package on CRAN. If it's a good package
> >>>> and people realize that it's good, and it remains available for others
> >>>> to use, then what problem is being solved?
> >>> I think the problem is that there is nothing to signal its importance. Perhaps
> >>> chron should be added to the "recommended" package list.
> >> I think that would be preferable to making it a base package, but it's
> >> not the only way to publicize it. Why not add something to the Wiki to
> >> compare the various possibilities for storing dates and times?
> >
> > As a recommended package it would be included in all binary releases
> > ensuring access without a separate install and would provide more
> > official endorsement.


> Yes, but that wasn't my question. A Wiki entry on dates and times would
> be useful whether chron is a recommended package or not. Why don't you
> write one based on your R News article, or at least write what you like
> about chron? The nice thing about wikis is that if you write anything
> inaccurate, someone else will come along and correct you; if you miss
> something, someone will add it.

> Duncan Murdoch


I think the R News article already sums up any knowledge I have on the subject. If anyone else has anything to add perhaps they could put that in the wiki. mailing list Received on Sun Jul 16 09:28:20 2006

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