[R] Manipulation of plot data in export file or 'in memory'

[Paul Murrell]

Hi


Greg Stewart wrote:
> 
> I'm trying to provide some help to someone using R in conjunction with
> Locfit who has v. little programming experience.
> 
> He would like to be able to do further manipulation of (contour) plot data
> to measure such things as area, and ideally to export the plots into another
> program for direct comparison with plot sets generated by other methods.


There is a way to access the coordinates for the contour lines that R
produces, but it is still experimental.  Please contact me privately if
you would like to know more about that.


> I suggested to him that it may be possible to export the plots in a file
> who's structure I know so that I could write conversion code to generate
> files that can be imported in another program. I also thought it might be
> possible to get a handle on the plot data structure in R (unless it's kept
> by Locfit) and work from there for analysis / export function (and possibly
> doing this with a C routine bound into R).
>
> I haven't found anything in the documentation that would help
> manipulate/understand graph export format or find handles. Could anyone
> provide advice? Any pointers would be much appreciated.


Graphical output in R is mostly just to a device (screen or postscript
or pdf or ...).  See help(Devices) for a list of what's available on
your system.  If the other software can read one of those formats then
you might be ok.

A memory-resident record is kept of the last "page" of output, but this
is used internally for redrawing and is not designed for external
tampering.  You can tamper with it;  it's just there's lots of potential
for doing something horrible to it.

Sorry if that's a bit vague :)  If you could tell me more precisely what
you're trying to do I might be able to produce some more useful
information.

Paul
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