[Rd] [R] RGui: windows-record and command history
Duncan Murdoch
murdoch at stats.uwo.ca
Fri Mar 24 14:04:18 CET 2006
I've moved this from r-help to r-devel.
On 3/23/2006 8:17 PM, Paul Murrell wrote:
>>
>> Paul,
>> If I read your comments correctly, the problem with manipulating the
>> graph history is with saved histories across sessions/versions. Is
>> there any reason not to manipulate it *within* a session? I never
>> save plots for re-use in R. Re-running code is usually best for me.
>> But I would find it handy to fiddle with the display list in a
>> session.
>
>
> That is *one* problem with the display list. Messing directly with the
> display list *within a session* is *less* dangerous, but R's behaviour
> if you do that is "undefined".
>
> The display list is technically an internal structure for R's internal
> use. We can't stop you playing with it, but I do not encourage it and
> it is not officially supported.
>
> There are a number of simple things that you could do to the display
> list that should work, but providing proper support for general
> manipulations of the display list would require a significant amount of
> (re)design of the R graphics code.
>
> Paul
>
> p.s. These comments apply to the display list in R's "graphics engine".
> The 'grid' package also maintains a display list, and that has been
> designed to support more general manipulations.
Are we talking about the same thing? I think Peter is only thinking of
manipulating the .SavedPlots variable, which is a Windows-only object
holding plot history. I imagine the entries in .SavedPlots[[5]] are the
things that you are worried about, and I agree people shouldn't play
with those, they should be using grid instead with its documented interface.
If we do warn people off manipulating .SavedPlots, then I think it
should be a higher priority to implement some manipulations ourselves,
e.g. "[<-.SavedPlots", to allow entries to be moved around or deleted in
the list.
Duncan
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