R help - Sep 2002 - Manipulation of plot data in export file or 'in memory'

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.

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.

Kind regards,

Greg Stewart
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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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