Re: Contour plots

[Ethan M. <merritt@u.washington.edu>]

On Friday 28 January 2005 12:41 am, Hans-Bernhard Broeker wrote:
> *) I'm strictly against any GUI-only feature.  Once we have a suitable
> command line method of specifying the locus of those contour labels, we 
> can think of a mouse interaction method of doing the same.  We may even 
> have to keep in mind that a GUI should be possible while setting up the 
> command line syntax.  But command line is still *mandatory*.

I think you are looking at this from the wrong direction.
A script to label contout plots is not a "GUI-only feature",
it is an example of a higher-level application you can build
on top of gnuplot's core functionality.

I suspect that creating a general contour-labelling algorithm is
hard enough, and speciallized enough, that it does not belong 
inside gnuplot.  Instead we should ask ourselves what core functions
would be needed to allow a higher-level program to be build on top
of gnuplot. I imagine that to be truly useful, this hypothetical
program would use a mixture of automated labelling and interactive
placement or editing.  

The mousing script is an example of how that externally-driven
interaction may already be supported. I don't know what, if any,
addition command line options might be needed also. The earlier
suggestion of letting the user specify a parametric function and
having gnuplot calculate the intersections with contour lines is
an interesting start.  I don't think you'd want gnuplot itself to
go ahead and place labels at those intersections, but it could
place them into an array of user-accessible coordinates.  The 
hypothetical higher-level application could then inspect the
intersections and choose to write a label there or not based
on how dense they are.


-- 
Ethan A Merritt       merritt@u.washington.edu
Biomolecular Structure Center
Mailstop 357742
University of Washington, Seattle, WA 98195