Re: [Matplotlib-users] odd "singular matrix" error

[Benjamin R. <ben...@ou...>]

What might be happening is that the patch being added has no area. The
logic it is failing in is in the autoscaling section, I believe. This is
why if there are other things already in the plot or with other patches,
then the code works fine because the limits aren't identical.

Still though, I thought we had enough logic checks to prevent this sort of
error. I see you are using Python 2.5, which is older than what we
currently support. Which version of matplotlib are you using?

Cheers!
Ben Root


On Wed, Dec 31, 2014 at 2:03 AM, C M <cmp...@gm...> wrote:

> I have no idea what this is. If I create a certain plot first in an
> application, it throws this error (edited to the key part):
>
> Traceback (most recent call last):
>
>   File "thescript.py", line 2147, in AddPatchBar
>     ax.add_patch(patch)
>   File "C:\Python25\lib\site-packages\matplotlib\axes.py", line 1471, in
> add_patch
>     self._update_patch_limits(p)
>   File "C:\Python25\lib\site-packages\matplotlib\axes.py", line 1492, in
> _update_patch_limits
>     self.transData.inverted())
>   File "C:\Python25\lib\site-packages\matplotlib\transforms.py", line
> 1954, in inverted
>     return CompositeGenericTransform(self._b.inverted(),
> self._a.inverted())
>   File "C:\Python25\lib\site-packages\matplotlib\transforms.py", line
> 1448, in inverted
>     self._inverted = Affine2D(inv(mtx))
>   File "C:\Python25\lib\site-packages\numpy\linalg\linalg.py", line 445,
> in inv
>     return wrap(solve(a, identity(a.shape[0], dtype=a.dtype)))
>   File "C:\Python25\lib\site-packages\numpy\linalg\linalg.py", line 328,
> in solve
>     raise LinAlgError, 'Singular matrix'
> numpy.linalg.linalg.LinAlgError: Singular matrix
>
> But, the odd part is that if I create a completely different and totally
> separate plot *before* this one, and *then* I try to plot this one, I do
> not get this error and this plot shows fine. That makes no sense to me. Or
> also, if I plot this "patch" on a plot with a few other lines plotted, it
> also works.
>
> Does anyone have any idea what could be causing this?  Thanks.
>
>
>
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