Re: desired features for gp backend?

[Rob Mahurin]

On Jun 18, 2009, at 10:37 AM, Ben Abbott wrote:
> It is not clear to me what aspect of the rendered figure would be  
> changed with preplot / postplot properties or with  
> initialize_plotting_engine / cleanup_plotting_engine.
>
> I suspect pre/post figure commands would have limited use. If such  
> were to be implemented, they would be more useful if they were  
> applied to the axes.


Here's an example I've been thinking about for a while: I'd like  
enough control over Octave's axes to make Tufte's "dot-dash" and  
"range-frame" plots.  There are currently examples of each at
        http://hupp.org/adam/weblog/category/tufte/

I can do the dot-dash axes in gnuplot with "set border 0" followed by  
"set xtics (...data...)" to put major and minor tics in the right  
place.  But in gnuplot, constructing a command from a datafile is  
something of a major undertaking.  In octave it's now a one-liner
        set(gca,"xticks", get(get(gca,"children"),"xdata"))
but that currently puts a label at every point without some clever set 
(gca,"xticklabel"), and apparently I can't yet specify minor ticks.

If there were a way to talk directly to the backend I could make  
something kludgy but workable, and incrementally request/contribute  
changes to the octave graphics handling that would let me get rid of  
the backend-specific stuff.  I was starting to do this when 3.0 came  
out and it suddenly became harder to talk to gnuplot directly.

It looks like I even sent a patch suggesting an octave syntax for  
axis ticks without lines, but it wasn't accepted:
	http://www.nabble.com/axis-manipulations-in-plots-are-unnecessarily- 
restrictive-td15880016.html

Rob

--
Rob Mahurin
University of Manitoba, Dept. of Physics & Astronomy
at:     Oak Ridge National Laboratory   865 207 2594
        Oak Ridge, Tennessee            address@hidden