From gavin.simpson at ucl.ac.uk  Wed Dec  8 11:59:47 2010
From: gavin.simpson at ucl.ac.uk (Gavin Simpson)
Date: Wed, 08 Dec 2010 10:59:47 +0000
Subject: [Rd] possible bug in chron packages
In-Reply-To: <AANLkTim1m5md+R9HHh2Vcao990mfxoeZJ+CP5YZUhPUX@mail.gmail.com>
References: <AANLkTim1m5md+R9HHh2Vcao990mfxoeZJ+CP5YZUhPUX@mail.gmail.com>
Message-ID: <1291805987.2418.19.camel@desktop.localdomain>

On Wed, 2010-12-08 at 11:26 +0100, Joris Meys wrote:
> Dear,
> 
> According to the documentation, the parameters given in "dates" are
> passed to the function "chron". When trying this out, it turns out
> that this apparently doesn't happen, eg:
> 
> > dates("20100101",format="Ymd",out.format="day mon year")
> [1] 01/01/10
> > chron("20100101",format="Ymd",out.format="day mon year")
> [1] 01 Jan 2010

It does actually. If you read the code and/or debug `dates` to see what
is happening, `out.format` is passed on to `chron` which does its thing
and passes back the correctly formatted object as specified by
`out.format`.

However, `dates` then goes on to unclass the returned object and then
stick back on a class. It also tries to preserve the "format" in the
first line of `dates`

fmt <- attr(x, "format")

but in your example this is NULL as `x` is just a character. The code
reapplies this stored format later on with

attr(out, "format") <- fmt

as the last line before returning out.

The "format" attribute of the object returned by `chron` never gets
stored or used on the object returned form `dates`.

G

> I would expect the outcome of both functions to be the same, or am I
> overlooking something?
> 
> Kind regards
> Joris
> 

-- 
%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%
 Dr. Gavin Simpson             [t] +44 (0)20 7679 0522
 ECRC, UCL Geography,          [f] +44 (0)20 7679 0565
 Pearson Building,             [e] gavin.simpsonATNOSPAMucl.ac.uk
 Gower Street, London          [w] http://www.ucl.ac.uk/~ucfagls/
 UK. WC1E 6BT.                 [w] http://www.freshwaters.org.uk
%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%



[Rd] possible bug in chron packages
Gavin Simpson