Re: [Rd] Strange behavior of pretty

From: Duncan Murdoch <murdoch_at_stats.uwo.ca>
Date: Sat, 03 Nov 2007 18:10:51 -0400

On 03/11/2007 4:34 PM, Ulrike Grmping 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



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