Closed
Description
I was trying to guess, in a dataframe with multi-indexed columns, how to select all columns with a given second-level value.
And then I hit an empty TypeError message
In [8]: df = pd.DataFrame(columns=['i', 'c', 'x', 'y'], data=[[0, 0, 1, 2], [1, 0, 3, 4], [0, 1, 1, 2], [1, 1, 3, 4]])
In [9]: dg
Out[9]:
x y
c 0 1 0 1
i
0 1 1 2 2
1 3 3 4 4
In [12]: dg = df.pivot_table(index='i', columns='c', values=['x', 'y'])
n [19]: dg['x', 0]
Out[19]:
i
0 1
1 3
Name: (x, 0), dtype: int64
In [20]: dg[:, 0]
---------------------------------------------------------------------------
TypeError Traceback (most recent call last)
<ipython-input-20-7eb22191791d> in <module>()
----> 1 dg[:, 0]
/home/nicolas/Git/pandas/pandas/core/frame.py in __getitem__(self, key)
1977 return self._getitem_frame(key)
1978 elif is_mi_columns:
-> 1979 return self._getitem_multilevel(key)
1980 else:
1981 return self._getitem_column(key)
/home/nicolas/Git/pandas/pandas/core/frame.py in _getitem_multilevel(self, key)
2021
2022 def _getitem_multilevel(self, key):
-> 2023 loc = self.columns.get_loc(key)
2024 if isinstance(loc, (slice, Series, np.ndarray, Index)):
2025 new_columns = self.columns[loc]
/home/nicolas/Git/pandas/pandas/indexes/multi.pyc in get_loc(self, key, method)
1526 key = _values_from_object(key)
1527 key = tuple(map(_maybe_str_to_time_stamp, key, self.levels))
-> 1528 return self._engine.get_loc(key)
1529
1530 # -- partial selection or non-unique index
/home/nicolas/Git/pandas/pandas/index.pyx in pandas.index.IndexEngine.get_loc (pandas/index.c:4005)()
135 util.set_value_at(arr, loc, value)
136
--> 137 cpdef get_loc(self, object val):
138 if is_definitely_invalid_key(val):
139 raise TypeError
/home/nicolas/Git/pandas/pandas/index.pyx in pandas.index.IndexEngine.get_loc (pandas/index.c:3617)()
137 cpdef get_loc(self, object val):
138 if is_definitely_invalid_key(val):
--> 139 raise TypeError
140
141 if self.over_size_threshold and self.is_monotonic_increasing:
TypeError: