where the ad_c["x"] will give an Index Error on my desktop. However, the same piece of code runs great in a different machine. The version of yt are the same in both machines, which is 3.0.2. Both of them installed yt through anaconda. The error message I got was following. Thanks for your help!

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IndexError                                Traceback (most recent call last)
<ipython-input-6-ff78a8bccc54> in <module>()
----> 1 ad_c["x"]

/home/fxyang/software/anaconda/lib/python2.7/site-packages/yt/data_objects/data_containers.pyc in __getitem__(self, key)
    243             if f in self._container_fields:
    244                 self.field_data[f] = \
--> 245                     self.ds.arr(self._generate_container_field(f))
    246                 return self.field_data[f]
    247             else:

/home/fxyang/software/anaconda/lib/python2.7/site-packages/yt/data_objects/construction_data_containers.pyc in _generate_container_field(self, field)
    587             np.multiply(rv, self.dds[2], rv)
    588         elif field == ("index", "x"):
--> 589             x = np.mgrid[self.left_edge[0] + 0.5*self.dds[0]:
    590                          self.right_edge[0] - 0.5*self.dds[0]:
    591                          self.ActiveDimensions[0] * 1j]

/home/fxyang/software/anaconda/lib/python2.7/site-packages/yt/units/yt_array.pyc in __getitem__(self, item)
    981
    982     def __getitem__(self, item):
--> 983         ret = super(YTArray, self).__getitem__(item)
    984         if ret.shape == ():
    985             return YTQuantity(ret, self.units)

IndexError: too many indices for array

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