BUG: setitem fails on mixed-type Panel4D

[stahlous]

Trying to set a value on a mixed-type Panel4D currently fails:

In [1]: from pandas.util import testing as tmd

In [2]: p4d = tmd.makePanel4D()

In [3]: p4d['foo'] = 'bar'

In [4]: p4d.iloc[0,0,0,0] = 0
---------------------------------------------------------------------------
AttributeError                            Traceback (most recent call last)
<ipython-input-4-bb74b95f7244> in <module>()
----> 1 p4d.iloc[0,0,0,0] = 0

/home/stahlous/pd_dev/pandas/pandas/core/indexing.py in __setitem__(self, key, value)
    119                 indexer = self._convert_to_indexer(key, is_setter=True)
    120
--> 121         self._setitem_with_indexer(indexer, value)
    122
    123     def _has_valid_type(self, k, axis):

/home/stahlous/pd_dev/pandas/pandas/core/indexing.py in _setitem_with_indexer(self, indexer, value)
    356             # indexer here
    357             if (len(labels) == 1 and
--> 358                     isinstance(self.obj[labels[0]].index, MultiIndex)):
    359                 item = labels[0]
    360                 obj = self.obj[item]

/home/stahlous/pd_dev/pandas/pandas/core/generic.py in __getattr__(self, name)
   1927         """
   1928         if name in self._internal_names_set:
-> 1929             return object.__getattribute__(self, name)
   1930         elif name in self._metadata:
   1931             return object.__getattribute__(self, name)

AttributeError: 'Panel' object has no attribute 'index'

Fortunately, it looks like a simple fix. If this looks OK. I'll add a note to v0.15.1.txt (doesn't have a GH issue number yet).

This fix is needed for my latest attempt at the fillna bug #8395.

[jreback]

tests!

[stahlous]

Ah... yeah. There is a test that highlights this in my fillna bug branch, but I guess that doesn't do any good here. I'll add a test as well to this branch.

[stahlous]

I added in a test which captures this issue. I also added in some tests for the non-mixed-type case since it looks like there weren't any tests of setting by index at all for Panel4D.

It looks like this only fixes setting by index for scalar values. Setting by index to a Series or DataFrame is still broken for mixed-type Panel4D. That fix is unfortunately not as trivial. I can work on the more comprehensive fix if you want to hold off merging in this partial fix. If you decide to merge in this PR, I can open an issue for the comprehensive fix.

[jreback]

keep things in separate PRs
open issues for things you believe are bugs

it's faster/easier to review s single fix at a time

[jreback]

don't use internal routines the thr release notes
setitem with a mixed dtype Panel4D was failing when setting with a scalar right (something like this

[stahlous]

Thanks. I added the issue number to test_setitem_by_indexer_mixed_type but not test_setitem_by_indexer since non-mixed-types were working as expected but just not tested.

[jreback]

merged via 1041dff

thanks!