From rpeng at jhsph.edu  Tue Mar 18 19:58:21 2008
From: rpeng at jhsph.edu (Roger D. Peng)
Date: Tue, 18 Mar 2008 14:58:21 -0400
Subject: [Rd] cut.Date and cut.POSIXt problem
In-Reply-To: <971536df0803181004x5ebbe960q6879506089b3e428@mail.gmail.com>
References: <971536df0803181004x5ebbe960q6879506089b3e428@mail.gmail.com>
Message-ID: <47E010CD.6090200@jhsph.edu>

Seems changes in r44116 force the interval to be single months (or years) 
instead of whatever the user specified.  I think the attached patches correct this.

Interestingly, 'cut' and 'seq' allow for the 'breaks' specification to be 
something like "3 months" but the documentation for 'hist' does not allow for 
this type of specification.

-roger

Gabor Grothendieck wrote:
> cut.Date and cut.POSIXt indicate that the breaks argument
> can be an integer followed by a space followed by "year", etc.
> but it seems the integer is ignored.
> 
> For example, I assume that breaks = "3 months" is supposed
> to cut it into quarters but, in fact, it cuts it into months as if
> 3 had not been there.
> 
>> d <- seq(Sys.Date(), length = 12, by = "month")
>> cut(d, "3 months")
>  [1] 2008-03-01 2008-04-01 2008-05-01 2008-06-01 2008-07-01 2008-08-01
> 2008-09-01 2008-10-01 2008-11-01 2008-12-01 2009-01-01 2009-02-01
> Levels: 2008-03-01 2008-04-01 2008-05-01 2008-06-01 2008-07-01
> 2008-08-01 2008-09-01 2008-10-01 2008-11-01 2008-12-01 2009-01-01
> 2009-02-01
>> cut(as.POSIXct(d), "3 months")
>  [1] 2008-03-01 2008-04-01 2008-05-01 2008-06-01 2008-07-01 2008-08-01
> 2008-09-01 2008-10-01 2008-11-01 2008-12-01 2009-01-01 2009-02-01
> Levels: 2008-03-01 2008-04-01 2008-05-01 2008-06-01 2008-07-01
> 2008-08-01 2008-09-01 2008-10-01 2008-11-01 2008-12-01 2009-01-01
> 2009-02-01
>> cut(as.POSIXlt(d), "3 months")
>  [1] 2008-03-01 2008-04-01 2008-05-01 2008-06-01 2008-07-01 2008-08-01
> 2008-09-01 2008-10-01 2008-11-01 2008-12-01 2009-01-01 2009-02-01
> Levels: 2008-03-01 2008-04-01 2008-05-01 2008-06-01 2008-07-01
> 2008-08-01 2008-09-01 2008-10-01 2008-11-01 2008-12-01 2009-01-01
> 2009-02-01
> 
> ______________________________________________
> R-devel at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-devel
> 

-- 
Roger D. Peng  |  http://www.biostat.jhsph.edu/~rpeng/
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[Rd] cut.Date and cut.POSIXt problem
Roger D. Peng