ValueError when using loc with TimedeltaIndex

[jdeschenes]

This snippet will work correctly:

import pandas as pd
df = pd.DataFrame({'x':range(10)})
cond = df['x'] > 3
df.loc[cond, 'x'] = 10 # Works properly

But when using a TimedeltaIndex:

import pandas as pd
df = pd.DataFrame({'x':range(10)})
df.index = pd.to_timedelta(range(10), unit='s')
cond = df['x'] > 3
df.loc[cond, 'x'] = 10 # ValueError is raised

pandas 0.18.1 has a different problem, but there is a workaround. Simple use the underlying numpy array:

df.loc[cond.values, 'x'] = 10 # Works as intended
df.loc[cond, 'x'] = 10 # No error, wrong results

Ouput

---

ValueError Traceback (most recent call last)
in ()
----> 1 df.loc[cond, 'x'] = 10

~/pandas/pandas/core/indexing.py in setitem(self, key, value)
138 else:
139 key = com._apply_if_callable(key, self.obj)
--> 140 indexer = self._get_setitem_indexer(key)
141 self._setitem_with_indexer(indexer, value)
142

~/pandas/pandas/core/indexing.py in _get_setitem_indexer(self, key)
120
121 if isinstance(key, tuple) and not self.ndim < len(key):
--> 122 return self._convert_tuple(key, is_setter=True)
123 if isinstance(key, range):
124 return self._convert_range(key, is_setter=True)

~/pandas/pandas/core/indexing.py in _convert_tuple(self, key, is_setter)
182 else:
183 for i, k in enumerate(key):
--> 184 idx = self._convert_to_indexer(k, axis=i, is_setter=is_setter)
185 keyidx.append(idx)
186 return tuple(keyidx)

~/pandas/pandas/core/indexing.py in _convert_to_indexer(self, obj, axis, is_setter)
1149 # if we are a label return me
1150 try:
-> 1151 return labels.get_loc(obj)
1152 except LookupError:
1153 if isinstance(obj, tuple) and isinstance(labels, MultiIndex):

~/pandas/pandas/tseries/tdi.py in get_loc(self, key, method, tolerance)
675 """
676
--> 677 if isnull(key):
678 key = tslib.NaT
679

~/pandas/pandas/core/generic.py in nonzero(self)
915 raise ValueError("The truth value of a {0} is ambiguous. "
916 "Use a.empty, a.bool(), a.item(), a.any() or a.all()."
--> 917 .format(self.class.name))
918
919 bool = nonzero

ValueError: The truth value of a Series is ambiguous. Use a.empty, a.bool(), a.item(), a.any() or a.all().

Versions

Here is my pd.show_versions(). It also has been tested on windows7 64 bits with version 0.19

INSTALLED VERSIONS

commit: f79bc7a
python: 3.5.2.final.0
python-bits: 64
OS: Linux
OS-release: 4.4.0-57-generic
machine: x86_64
processor: x86_64
byteorder: little
LC_ALL: None
LANG: en_CA.UTF-8
LOCALE: en_CA.UTF-8

pandas: 0.19.0+243.gf79bc7a
nose: None
pip: 9.0.1
setuptools: 27.2.0
Cython: 0.25.2
numpy: 1.11.2
scipy: 0.18.1
statsmodels: None
xarray: None
IPython: 5.1.0
sphinx: None
patsy: None
dateutil: 2.6.0
pytz: 2016.10
blosc: None
bottleneck: None
tables: None
numexpr: None
matplotlib: None
openpyxl: None
xlrd: None
xlwt: None
xlsxwriter: None
lxml: None
bs4: None
html5lib: None
httplib2: None
apiclient: None
sqlalchemy: None
pymysql: None
psycopg2: None
jinja2: None
s3fs: None
pandas_datareader: None

[jreback]

this is quite subtle. When a boolean array is presented, .get_loc() should raise a TypeError if it cannot handle (and so this hits a different path). However, looks like the .get_loc on a TimedeltaIndex is wrong.

This patch makes it work. If you could do a PR with some tests and a 1-liner about why this is needed, would be great. The basic issue is that .get_loc should raise a TypeError if it cannot handle the type of the key (rather than erroring with a ValueError in this case).

diff --git a/pandas/tseries/tdi.py b/pandas/tseries/tdi.py
index 1585aac..1e4986a 100644
--- a/pandas/tseries/tdi.py
+++ b/pandas/tseries/tdi.py
@@ -14,7 +14,8 @@ from pandas.types.common import (_TD_DTYPE,
                                  _ensure_int64)
 from pandas.types.missing import isnull
 from pandas.types.generic import ABCSeries
-from pandas.core.common import _maybe_box, _values_from_object
+from pandas.core.common import (_maybe_box, _values_from_object,
+                                is_bool_indexer)
 
 from pandas.core.index import Index, Int64Index
 import pandas.compat as compat
@@ -674,6 +675,9 @@ class TimedeltaIndex(DatetimeIndexOpsMixin, TimelikeOps, Int64Index):
         loc : int
         """
 
+        if is_bool_indexer(key):
+            raise TypeError
+
         if isnull(key):
             key = tslib.NaT