[matplotlib-devel] Should Path objects have an initial MOVETO? (was: error with basemap and pdf)

[Jouni K. S. <jk...@ik...>]

Jeff Whitaker <js...@fa...> writes:

> Jouni:  That test script now crashes with:
>
>   File "/Users/jwhitaker/lib/python/matplotlib/backends/backend_pdf.py", 
> line 1214, in pathOperations
>     raise ValueError, 'Path lacks initial MOVETO'
> ValueError: Path lacks initial MOVETO

I think this confirms my suspicion that the bug is really elsewhere. A
path in PDF needs to begin with a "m" that sets the initial point, and
that particular Path object only consisted of one LINETO operation. Am I
correct in thinking that this is an invalid path?

I'm not too familiar with Path (and I'm terribly busy today) but I think
the way to catch this bug is to add a sanity check to Path, similar to
the check in the pdf backend that produces that error. Then the
traceback would show what code is creating the invalid path -- the
traceback from the backend is too late in the execution to tell us that.

-- 
Jouni K. Seppänen
http://www.iki.fi/jks