[yt-dev] Issue #1131: auto=True does not work for Camera (yt_analysis/yt)

[Andrew Myers]

New issue 1131: auto=True does not work for Camera
https://bitbucket.org/yt_analysis/yt/issues/1131/auto-true-does-not-work-for-camera

Andrew Myers:

According to the docstrings, this should work:

```
#!python

from yt.visualization.volume_rendering.api import Camera
ds = yt.load('IsolatedGalaxy/galaxy0030/galaxy0030')
cam = Camera(ds, auto=True)

```

but when I run the above code I get the following error:


```
#!python


---------------------------------------------------------------------------
TypeError                                 Traceback (most recent call last)
<ipython-input-4-a555f68d57d9> in <module>()
      2 from yt.visualization.volume_rendering.api import Camera
      3 ds = yt.load('IsolatedGalaxy/galaxy0030/galaxy0030')
----> 4 cam = Camera(ds, auto=True)

/Users/atmyers/yt-x86_64/src/yt-hg/yt/visualization/volume_rendering/camera.py in __init__(self, data_source, lens_type, auto)
     95         self._position = np.array([1.0]*3)
     96         self.set_lens(lens_type)
---> 97         if data_source is not None:
     98             data_source = data_source_or_all(data_source)
     99             self._focus = data_source.ds.domain_center

/Users/atmyers/yt-x86_64/src/yt-hg/yt/visualization/volume_rendering/camera.py in set_defaults_from_data_source(self, data_source)
    216         if lens_type not in lenses:
    217             mylog.error("Lens type not available")
--> 218             raise RuntimeError()
    219         self.lens = lenses[lens_type]()
    220         self.lens.camera = self

/Users/atmyers/yt-x86_64/src/yt-hg/yt/visualization/volume_rendering/camera.py in fset(self, value)
    118 
    119         def fget(self):
--> 120             return self._position
    121 
    122         def fset(self, value):

/Users/atmyers/yt-x86_64/src/yt-hg/yt/visualization/volume_rendering/camera.py in switch_orientation(self, normal_vector, north_vector)
    304         north_vector : array_like, optional
    305             The 'up' direction for the plane of rays.  If not specific,
--> 306             calculated automatically.
    307         """
    308         if north_vector is None:

/Users/atmyers/yt-x86_64/src/yt-hg/yt/utilities/orientation.pyc in _setup_normalized_vectors(self, normal_vector, north_vector)
     72 
     73         # Now we set up our various vectors
---> 74         normal_vector /= np.sqrt(np.dot(normal_vector, normal_vector))
     75         if north_vector is None:
     76             vecs = np.identity(3)

TypeError: unsupported operand type(s) for *: 'NoneType' and 'NoneType'
```

Responsible: atmyers