Description
Code Sample, a copy-pastable example if possible
In [2]: mi = pd.MultiIndex(levels=[[1, 2, 3, 5], [4, 6]], labels=[[3, 1, 2, 0], [1, -1, 0, -1]])
In [3]: mi.get_loc((2, np.nan))
---------------------------------------------------------------------------
KeyError Traceback (most recent call last)
<ipython-input-3-d77b20d4d7a2> in <module>()
----> 1 mi.get_loc((2, np.nan))
/home/pietro/nobackup/repo/pandas/pandas/core/indexes/multi.py in get_loc(self, key, method)
2119 key = _values_from_object(key)
2120 key = tuple(map(_maybe_str_to_time_stamp, key, self.levels))
-> 2121 return self._engine.get_loc(key)
2122
2123 # -- partial selection or non-unique index
/home/pietro/nobackup/repo/pandas/pandas/_libs/index.pyx in pandas._libs.index.MultiIndexObjectEngine.get_loc (pandas/_libs/index.c:14965)()
616 return super(MultiIndexObjectEngine, self).get_indexer(values)
617
--> 618 cpdef get_loc(self, object val):
619
620 # convert a MI to an ndarray
/home/pietro/nobackup/repo/pandas/pandas/_libs/index.pyx in pandas._libs.index.MultiIndexObjectEngine.get_loc (pandas/_libs/index.c:14886)()
621 if hasattr(val, 'values'):
622 val = val.values
--> 623 return super(MultiIndexObjectEngine, self).get_loc(val)
624
625
/home/pietro/nobackup/repo/pandas/pandas/_libs/index.pyx in pandas._libs.index.IndexEngine.get_loc (pandas/_libs/index.c:5832)()
137 util.set_value_at(arr, loc, value)
138
--> 139 cpdef get_loc(self, object val):
140 if is_definitely_invalid_key(val):
141 raise TypeError("'{val}' is an invalid key".format(val=val))
/home/pietro/nobackup/repo/pandas/pandas/_libs/index.pyx in pandas._libs.index.IndexEngine.get_loc (pandas/_libs/index.c:5678)()
159
160 try:
--> 161 return self.mapping.get_item(val)
162 except (TypeError, ValueError):
163 raise KeyError(val)
/home/pietro/nobackup/repo/pandas/pandas/_libs/hashtable_class_helper.pxi in pandas._libs.hashtable.PyObjectHashTable.get_item (pandas/_libs/hashtable.c:21018)()
1263 sizeof(uint32_t)) # flags
1264
-> 1265 cpdef get_item(self, object val):
1266 cdef khiter_t k
1267 if val != val or val is None:
/home/pietro/nobackup/repo/pandas/pandas/_libs/hashtable_class_helper.pxi in pandas._libs.hashtable.PyObjectHashTable.get_item (pandas/_libs/hashtable.c:20972)()
1271 return self.table.vals[k]
1272 else:
-> 1273 raise KeyError(val)
1274
1275 cpdef set_item(self, object key, Py_ssize_t val):
KeyError: (2, nan)
In [4]: mi.get_indexer(mi.copy())
Out[4]: array([ 0, -1, 2, -1])
In [5]: mi == mi.copy()
Out[5]: array([ True, False, True, False], dtype=bool)Problem description
I think this is actually the cause for this example, which is different from the one reported at the top of #18455 .
Expected Output
array([ 0, 1, 2, 3])
Output of pd.show_versions()
INSTALLED VERSIONS
commit: b45325e
python: 3.5.3.final.0
python-bits: 64
OS: Linux
OS-release: 4.9.0-4-amd64
machine: x86_64
processor:
byteorder: little
LC_ALL: None
LANG: en_GB.UTF-8
LOCALE: en_GB.UTF-8
pandas: 0.22.0.dev0+201.gb45325e28
pytest: 3.0.6
pip: 9.0.1
setuptools: 33.1.1
Cython: 0.25.2
numpy: 1.12.1
scipy: 0.18.1
pyarrow: None
xarray: None
IPython: 5.2.2
sphinx: None
patsy: 0.4.1+dev
dateutil: 2.6.0
pytz: 2016.10
blosc: None
bottleneck: 1.2.0
tables: 3.3.0
numexpr: 2.6.1
feather: 0.3.1
matplotlib: 2.0.0
openpyxl: 2.3.0
xlrd: 1.0.0
xlwt: 1.2.0
xlsxwriter: None
lxml: 3.7.1
bs4: 4.5.3
html5lib: 0.999999999
sqlalchemy: 1.0.15
pymysql: None
psycopg2: None
jinja2: 2.8
s3fs: None
fastparquet: None
pandas_gbq: None
pandas_datareader: None