[R] abline outside of plot region

[Rolf Turner]

On 30/04/11 01:14, Nick Sabbe wrote:
> Hi R people.
>
>
>
> I ran into this problem: I created a plot with errbars, like this:
>
>> errbar(x=c(1,2,3,4), y=c(2,1,3,3), yminus=c(1.5,0.5,2.5,2.5),
> yplus=c(2.5,1.5,3.5,3.5))
>
> Next, I wanted to accentuate some x value with an abline, like this:
>
>> abline(v=2)
>
>
> In one of my R sessions (which admittedly I have had open for quite a while
> now), the abline draws outside of the plotting region of errbars (till the
> edge of my plotting window at least).
>
> I tested for the cause by opening another session (clean) of the same
> version of R (2.13), and running the same set of commands. In this session,
> I do not have this behavior. Conclusion: I must have changed some graphical
> parameter in my original session, but I don't know which one. Do you?
<SNIP>

I think what has happened is not that *you* changed some graphical 
parameter,
but rather that the package Hmisc did.  In a rather strange way.  (I 
*presume*
that you are using the errbar() function out of Hmisc rather than out of the
sfsmisc package --- you didn't say).

For a while I thought that the problem was associated with the 
*installation*
of Hmisc, becomes it seemed to happen only on the first occasion after I
did the install, and on later occasions (quit from R, restart, load Hmisc,
try errbar and abline) the problem did not occur.

But then, about the third time I tried the re-install, the problem never 
happened
at all.  But it ***did*** happen, a couple of times.  So you're not 
imagining it,
you'll be pleased to know.

I think that if it *does* happen to you again, you can fix it by setting

     par(xpd=FALSE)

I checked on par()$xpd a couple of times when the problem occurred,
and got NA, which is consistent with the observed problem.

The whole thing is weird, but.  Gremlins?

     cheers,

         Rolf Turner