From murdoch at stats.uwo.ca  Sat Nov  3 23:10:51 2007
From: murdoch at stats.uwo.ca (Duncan Murdoch)
Date: Sat, 03 Nov 2007 18:10:51 -0400
Subject: [Rd] Strange behavior of pretty
In-Reply-To: <13566672.post@talk.nabble.com>
References: <13566672.post@talk.nabble.com>
Message-ID: <472CF1EB.9020703@stats.uwo.ca>

On 03/11/2007 4:34 PM, Ulrike Gr?mping wrote:
> Dear all,
> 
> I got stuck with a weird behavior of pretty:
>     pretty(c(-1,1),n=1)
> yields -2, 0, 2 instead of the desired result -1 1.
> Likewise, 
>     pretty(c(-2,2),n=1)
> yields -5, 0, 5 instead of the desired result -2 2.

I don't think pretty() should ever return -1 1 or -2 2.  It should 
always return multiples of some round number, so it would have to 
include 0.  But I don't see why it is expanding the range.  It doesn't 
do that when the results are non-negative, e.g.

 > pretty(0:1, n=1)
[1] 0 1
 > pretty(0:2, n=1)
[1] 0 2

> With n=0, the result is the same, while with n=2 everything is as
> documented.
> 
> This behavior nastily messed up some of my cube plots. Is there any chance
> that this can be fixed? 

The documentation has been sitting for 8 years with "FIXME" notes in it, 
so I wouldn't hold my breath.

Duncan Murdoch



[Rd] Strange behavior of pretty
Duncan Murdoch