saving plots as objects?

On Friday 27 February 2004 01:22, Prof Brian Ripley wrote:

On Thu, 26 Feb 2004, Deepayan Sarkar wrote:

On Thursday 26 February 2004 14:47, Rajarshi Guha wrote:

Hi I had two questions regarding plots:

* Is there are way to save a plot in the form of an object such that
it could be displayed/modified later?

Depends on what you want to do. Probably not for regular (base) plots.

I think ?recordPlot does this, at least to allow plots to be saved,
displayed again and added to.

Ah, I didn't know that.

The
grid package has a concept of objects that can be edited (before
and/or after plotting them). Functions in the lattice package produce
objects that may be close to what you want. They are not plots
themselves, but rather a self-contained description of a plot (in the
sense that they contain the data as well as instructions on how to
plot it). The data part cannot be easily changed, but almost
everything else can be manipulated before plotting.

AFAIK that internal description is not documented and there are no
end-user tools for doing the manipulation.  Can you please point us to
details?   I suspect nothing can _easily_ be changed by end-users at
present.

There has always been an update() method that's supposed to be used for 
this. No one uses it much, and it probably has a few bugs (but should be 
improved in time for R 1.9.0). From ?xyplot:

Value:

     An object of class ``trellis''. The `update' method can be used to
     update components of the object and the `print' method (usually
     called by default) will plot it on an appropriate plotting device.