[Rd] arrows() doesn't like zero-length arrows (PR#727)
ripley@stats.ox.ac.uk
ripley@stats.ox.ac.uk
Tue, 7 Nov 2000 22:58:35 +0100 (MET)
On Tue, 7 Nov 2000 stephen@cogsci.ed.ac.uk wrote:
> Hi,
>
> By going through the mailing list archives, I noticed that people use
> the arrows() command to add error bars to their plots. I think there
> is a problem when trying to draw arrows of zero length. In the
> following code, certainly the x driver produces an odd-angled line.
> In the postscript device, NaNQ values are generated; when the
> postscript file is viewed in Ghostview, an error is then generated.
>
> Sample run:
>
> postscript(file="test.ps")
> x <- c(0, 1, 2)
> y <- c(0, -0.5, 0.3)
> s <- c(0, 0.1, 0.1)
> plot(x,y)
> arrows(x, y-s, x, y+s, code=3, angle=90)
> dev.off()
>
> Looking in the file test.ps I see the following (around line 160):
>
> np
> 103.58 354.24 m
> 103.58 354.24 l
> o
> np
> NaNQ NaNQ m
> 103.58 354.24 l
> NaNQ NaNQ l
>
> This was with R Version 1.1.1 (August 15, 2000) (running on OSF/1).
OS-specific (most OSes do sensible things), and already solved in the
development version. There was some discussion of this (Christian Ritter)
on R-help AFAIR a while back.
--
Brian D. Ripley, ripley@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 272860 (secr)
Oxford OX1 3TG, UK Fax: +44 1865 272595
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