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

[C M <cmp...@gm...>]

On Wed, Dec 31, 2014 at 9:45 AM, Benjamin Root <ben...@ou...> wrote:

> 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.
>

If it is helpful, when I print the value of the patch, I get this:

 patch is:  Poly((735597, -12) ...)

What's weird though, is that the other plot I'm talking about is a
*different* plot entirely (different canvas instance), and can be closed
first and still "allow" the patch plot to be shown without errors.

>
> 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?
>

I'm using matplotlib 1.1.0. I could try upgrading.



>
> 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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>