[R] ?bug? strange factors produced by chron

[Petr Pikal]

Hi

On 13 Feb 2006 at 12:04, Prof Brian Ripley wrote:

Date sent:      	Mon, 13 Feb 2006 12:04:49 +0000 (GMT)
From:           	Prof Brian Ripley <ripley at stats.ox.ac.uk>
To:             	Petr Pikal <petr.pikal at precheza.cz>
Copies to:      	r-help at stat.math.ethz.ch
Subject:        	Re: [R] ?bug? strange factors produced by chron

> On Mon, 13 Feb 2006, Petr Pikal wrote:
> 
> > Thank you very much.
> >
> > On 13 Feb 2006 at 10:54, Prof Brian Ripley wrote:
> >
> > Date sent:      	Mon, 13 Feb 2006 10:54:21 +0000 (GMT)
> > From:           	Prof Brian Ripley <ripley at stats.ox.ac.uk>
> > To:             	Petr Pikal <petr.pikal at precheza.cz>
> > Copies to:      	r-help at stat.math.ethz.ch
> > Subject:        	Re: [R] ?bug? strange factors produced by chron
> >
> >> 1) The obvious test is via is.factor(), and you have not used that.
> >
> > I used it with TRUE result but did not use in my post (mea culpa)
> >> is.factor(kvartaly)
> > [1] TRUE
> >
> >> 2) Your example works for me, so what versions of R and chron is
> >> this?
> >
> > Package: chron
> > Version: 2.3-1
> > R 2.2.1 and W2000
> >
> > but problem is probably in interaction (see below)
> >>
> >> 3) Here's my guess. split is using the C-level test isFactor.  That
> >> tests that the factor is of type integer, so please try
> >>
> >>>  typeof(kvartaly)
> >
> > > typeof(kvartaly)
> > [1] "double"
> >
> > Problem is probably not in chron but in interaction, which silently
> > transfers factor type to double
> >
> >> typeof(factor(letters[1:2]))
> > [1] "integer"
> >
> >> typeof(interaction(factor(letters[1:2]), factor(letters[3:4])))
> > [1] "double"
> 
> 2.2.1 does not do that for me (and contains ans <- as.integer(ans),
> and has since Sept 2001).  Do you have a private copy?

Yes, you have got it. I used (probably due to different handling of 
drop) a copy of interaction from Hmisc package from 2001, where there 
is no as.integer(ans). I'll switch to base version and see if there 
is no other problems with some of my code. 

As I noticed this behaviour only recently and use interaction from 
time to time so some other change had to sneaked around me without 
noticing.

Thank you again.

Best regards.
Petr

> 
> -- 
> Brian D. Ripley,                  ripley at stats.ox.ac.uk
> Professor of Applied Statistics,  http://www.stats.ox.ac.uk/~ripley/
> University of Oxford,             Tel:  +44 1865 272861 (self) 1 South
> Parks Road,                     +44 1865 272866 (PA) Oxford OX1 3TG,
> UK                Fax:  +44 1865 272595
> 
> ______________________________________________
> R-help at stat.math.ethz.ch mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide!
> http://www.R-project.org/posting-guide.html

Petr Pikal
petr.pikal at precheza.cz