[SciPy-dev] gplt suggestion: initcmd

[Michael J Gruber]

SciPy version: 0.3.2

When using the gplt module for batch processing plots there are two
problems:

- gplt sets the default terminal to X11, so that you have to have X
running (or Xfb).

- gplt sends "reset" for every plot", and implements set commands (range
etc) as "replots". In particular, ranges get reset when setting up
output to a file!

As an example, I want to generate 500 plots depending on a parameter,
but with the same range so that the plots fit together as an animation.

The attached diffs change "plot" and "_init_plot" so that plot has an
optional keyword parameter "initcmd". If it is not specified or None,
plot behaves as before (sending a "reset" to gnuplot for every plot).
If specified, it is sent (instead of reset) verbatim to gnuplot.

This allows to do something like the following:

# xvals is an arry of x coordinates
initcmd='set yrange [-5:40]; set xrange [0:1]; set terminal jpeg size
1000,750;

for j in range(500):
  plotdata = myplotproc(j)
  gplt.plot(xvals,plotdata,"initcmd=initcmd+'set output
"'+prefix+('%0.3d.jpeg"' % j))

(The mailer may introduce linebreaks in the code above.)

That way, there are no replots involved, no X needs to be running. One
could arrange for range and term to be set only once, but this no
performance issue.

I'll appreciate any feedback.

Cheers,
Michael

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