Hi,
I'm looking into replacing my MATLAB(R) plotting routines by something
slicker, and quite naturally found matplotlib. It has all the
capabilities that I would need, except that I can't yet transform my
plots into TikZ.
For MATLAB(R), I used this rather elaborate script
<http://win.ua.ac.be/~nschloe/content/matlab2tikz>.
Well, I thought I can just go ahead and start writing and equivalent
backend; the documentation is really nice and clear (quite unlike
MATLAB's!) so it was no big problem to get into the concepts of the
backend. I played around a little and thought about how I could
implement this and that, and some questions arose which can maybe best
answered here.
For the sake of clarity, let me just give a snippet of Pgfplots (TikZ)
code that I would like the backend to produce
===================== *snip* =====================
[...]
\begin{semilogyaxis}
[axis on top,
xtick={2,4,6,8,10,12,14,16},
ytick={1e-15,1e-10,1e-05,1,100000},
xmin=0.000000e+00,xmax=1.700000e+01,
ymin=1.000000e-15,ymax=1.000000e+05,
xmajorgrids,
ymajorgrids,
title={$\norm{F(\psi)}_2$},
xlabel={$k$},
width=\figurewidth,
height=\figureheight,
scale only axis
]
% Line plot
\addplot [color=red,only marks,mark=*,mark options={solid,fill=red}]
coordinates{
(1.000000e+00,3.206000e+01) (2.000000e+00,3.860000e+01)
(3.000000e+00,1.421000e+03) (4.000000e+00,4.143000e+02)
(5.000000e+00,1.445000e+02) (6.000000e+00,3.775000e+01)
(7.000000e+00,7.455000e+00) (8.000000e+00,7.228000e-01)
(9.000000e+00,2.275000e-02) (1.000000e+01,4.953000e-05)
(1.100000e+01,9.718000e-10) (1.200000e+01,5.534000e-07)
(1.300000e+01,4.217000e-11) (1.400000e+01,3.930000e-03)
(1.500000e+01,2.067000e-07) (1.600000e+01,7.231000e-12)
};
\end{semilogyaxis}
[...]
===================== *snap* =====================
This yields a purely marker plot (without lines) on a coordinate
system where the y-coordinate is log-scaled. You see that the code is
rather semantic and can easily be edited (which is think is the whole
point of Pgfplots as opposed to pure TikZ).
Now, if for a matplotlib plot I had query functions for the the axes
ranges, ticks, grids, titles, data values, and so on and so forth, it
would be a more or less complicated parsing of those and creating what
we see above.
However, it seems to me that the concept of backends is different.
draw_path() would be called to plot the graph itself, the coordinate
axes, and basically everything that resembles a line, giving its
outline (color, shape, markers, start and end points) but *no*
semantic information, that is, whether the path is part of an axis, an
arrow or whatever.
Is that correct?
Considering this, what do matplotlob masterbrains 
think would be a
good way to extract Pgfplots code out of a matplotlib figure? Is a
backend feasible at all? Would a function as "matplotlib2tikz(
myFigure )" be more advisable, making use of all sorts of query
functions? (Such as myFigure.axes.get_xlim() -- Does something like
that exist at all?)
Cheers,
Nico
think would be a