BUG: fix index op names and pinning

pandas/core/indexes/datetimelike.py

@@ -669,6 +669,7 @@ def __add__(self, other):
                 return self._add_offset_array(other)
             elif isinstance(self, TimedeltaIndex) and isinstance(other, Index):
                 if hasattr(other, '_add_delta'):
+                    # i.e. DatetimeIndex, TimedeltaIndex, or PeriodIndex
                     return other._add_delta(self)
                 raise TypeError("cannot add TimedeltaIndex and {typ}"
                                 .format(typ=type(other)))
@@ -685,7 +686,11 @@ def __add__(self, other):
                 return NotImplemented
 
         cls.__add__ = __add__
-        cls.__radd__ = __add__
+
+        def __radd__(self, other):
+            # alias for __add__
+            return self.__add__(other)
+        cls.__radd__ = __radd__
 
         def __sub__(self, other):
             from pandas.core.index import Index
@@ -704,10 +709,10 @@ def __sub__(self, other):
                 # Array/Index of DateOffset objects
                 return self._sub_offset_array(other)
             elif isinstance(self, TimedeltaIndex) and isinstance(other, Index):
-                if not isinstance(other, TimedeltaIndex):
-                    raise TypeError("cannot subtract TimedeltaIndex and {typ}"
-                                    .format(typ=type(other).__name__))
-                return self._add_delta(-other)
+                # We checked above for timedelta64_dtype(other) so this
+                # must be invalid.
+                raise TypeError("cannot subtract TimedeltaIndex and {typ}"
+                                .format(typ=type(other).__name__))
             elif isinstance(other, DatetimeIndex):
                 return self._sub_datelike(other)
             elif is_integer(other):
@@ -732,8 +737,15 @@ def __rsub__(self, other):
             return -(self - other)
         cls.__rsub__ = __rsub__
 
-        cls.__iadd__ = __add__
-        cls.__isub__ = __sub__
+        def __iadd__(self, other):
+            # alias for __add__
+            return self.__add__(other)
+        cls.__iadd__ = __iadd__
+
+        def __isub__(self, other):
+            # alias for __sub__
+            return self.__sub__(other)
+        cls.__isub__ = __isub__
 
     def _add_delta(self, other):
         return NotImplemented

pandas/core/indexes/datetimes.py

@@ -100,10 +100,11 @@ def f(self):
     return property(f)
 
 
-def _dt_index_cmp(opname, cls, nat_result=False):
+def _dt_index_cmp(opname, cls):
     """
     Wrap comparison operations to convert datetime-like to datetime64
     """
+    nat_result = True if opname == '__ne__' else False
 
     def wrapper(self, other):
         func = getattr(super(DatetimeIndex, self), opname)
@@ -291,7 +292,7 @@ def _join_i8_wrapper(joinf, **kwargs):
     def _add_comparison_methods(cls):
         """ add in comparison methods """
         cls.__eq__ = _dt_index_cmp('__eq__', cls)
-        cls.__ne__ = _dt_index_cmp('__ne__', cls, nat_result=True)
+        cls.__ne__ = _dt_index_cmp('__ne__', cls)
         cls.__lt__ = _dt_index_cmp('__lt__', cls)
         cls.__gt__ = _dt_index_cmp('__gt__', cls)
         cls.__le__ = _dt_index_cmp('__le__', cls)

pandas/core/indexes/period.py

@@ -75,26 +75,25 @@ def dt64arr_to_periodarr(data, freq, tz):
 _DIFFERENT_FREQ_INDEX = period._DIFFERENT_FREQ_INDEX
 
 
-def _period_index_cmp(opname, cls, nat_result=False):
+def _period_index_cmp(opname, cls):
     """
-    Wrap comparison operations to convert datetime-like to datetime64
+    Wrap comparison operations to convert Period-like to PeriodDtype
     """
+    nat_result = True if opname == '__ne__' else False
 
     def wrapper(self, other):
+        op = getattr(self._ndarray_values, opname)
         if isinstance(other, Period):
-            func = getattr(self._ndarray_values, opname)
-            other_base, _ = _gfc(other.freq)
             if other.freq != self.freq:
                 msg = _DIFFERENT_FREQ_INDEX.format(self.freqstr, other.freqstr)
                 raise IncompatibleFrequency(msg)
 
-            result = func(other.ordinal)
+            result = op(other.ordinal)
         elif isinstance(other, PeriodIndex):
             if other.freq != self.freq:
                 msg = _DIFFERENT_FREQ_INDEX.format(self.freqstr, other.freqstr)
                 raise IncompatibleFrequency(msg)
 
-            op = getattr(self._ndarray_values, opname)
             result = op(other._ndarray_values)
 
             mask = self._isnan | other._isnan
@@ -107,8 +106,7 @@ def wrapper(self, other):
             result.fill(nat_result)
         else:
             other = Period(other, freq=self.freq)
-            func = getattr(self._ndarray_values, opname)
-            result = func(other.ordinal)
+            result = op(other.ordinal)
 
         if self.hasnans:
             result[self._isnan] = nat_result
@@ -230,7 +228,7 @@ class PeriodIndex(DatelikeOps, DatetimeIndexOpsMixin, Int64Index):
     def _add_comparison_methods(cls):
         """ add in comparison methods """
         cls.__eq__ = _period_index_cmp('__eq__', cls)
-        cls.__ne__ = _period_index_cmp('__ne__', cls, nat_result=True)
+        cls.__ne__ = _period_index_cmp('__ne__', cls)
         cls.__lt__ = _period_index_cmp('__lt__', cls)
         cls.__gt__ = _period_index_cmp('__gt__', cls)
         cls.__le__ = _period_index_cmp('__le__', cls)

pandas/core/indexes/range.py

@@ -15,6 +15,7 @@
 from pandas.compat.numpy import function as nv
 
 import pandas.core.common as com
+from pandas.core import ops
 from pandas.core.indexes.base import Index, _index_shared_docs
 from pandas.util._decorators import Appender, cache_readonly
 import pandas.core.dtypes.concat as _concat
@@ -569,16 +570,12 @@ def __floordiv__(self, other):
     def _add_numeric_methods_binary(cls):
         """ add in numeric methods, specialized to RangeIndex """
 
-        def _make_evaluate_binop(op, opstr, reversed=False, step=False):
+        def _make_evaluate_binop(op, step=False):
             """
             Parameters
             ----------
             op : callable that accepts 2 parms
                 perform the binary op
-            opstr : string
-                string name of ops
-            reversed : boolean, default False
-                if this is a reversed op, e.g. radd
             step : callable, optional, default to False
                 op to apply to the step parm if not None
                 if False, use the existing step
@@ -588,13 +585,11 @@ def _evaluate_numeric_binop(self, other):
                 if isinstance(other, ABCSeries):
                     return NotImplemented
 
-                other = self._validate_for_numeric_binop(other, op, opstr)
+                other = self._validate_for_numeric_binop(other, op)
                 attrs = self._get_attributes_dict()
                 attrs = self._maybe_update_attributes(attrs)
 
                 left, right = self, other
-                if reversed:
-                    left, right = right, left
 
                 try:
                     # apply if we have an override
@@ -628,43 +623,26 @@ def _evaluate_numeric_binop(self, other):
 
                     return result
 
-                except (ValueError, TypeError, AttributeError,
-                        ZeroDivisionError):
+                except (ValueError, TypeError, ZeroDivisionError):
                     # Defer to Int64Index implementation
-                    if reversed:
-                        return op(other, self._int64index)
                     return op(self._int64index, other)
+                    # TODO: Do attrs get handled reliably?
 
             return _evaluate_numeric_binop
 
-        cls.__add__ = cls.__radd__ = _make_evaluate_binop(
-            operator.add, '__add__')
-        cls.__sub__ = _make_evaluate_binop(operator.sub, '__sub__')
-        cls.__rsub__ = _make_evaluate_binop(
-            operator.sub, '__sub__', reversed=True)
-        cls.__mul__ = cls.__rmul__ = _make_evaluate_binop(
-            operator.mul,
-            '__mul__',
-            step=operator.mul)
-        cls.__truediv__ = _make_evaluate_binop(
-            operator.truediv,
-            '__truediv__',
-            step=operator.truediv)
-        cls.__rtruediv__ = _make_evaluate_binop(
-            operator.truediv,
-            '__truediv__',
-            reversed=True,
-            step=operator.truediv)
+        cls.__add__ = _make_evaluate_binop(operator.add)
+        cls.__radd__ = _make_evaluate_binop(ops.radd)
+        cls.__sub__ = _make_evaluate_binop(operator.sub)
+        cls.__rsub__ = _make_evaluate_binop(ops.rsub)
+        cls.__mul__ = _make_evaluate_binop(operator.mul, step=operator.mul)
+        cls.__rmul__ = _make_evaluate_binop(ops.rmul, step=ops.rmul)
+        cls.__truediv__ = _make_evaluate_binop(operator.truediv,
+                                               step=operator.truediv)
+        cls.__rtruediv__ = _make_evaluate_binop(ops.rtruediv,
+                                                step=ops.rtruediv)
         if not compat.PY3:
-            cls.__div__ = _make_evaluate_binop(
-                operator.div,
-                '__div__',
-                step=operator.div)
-            cls.__rdiv__ = _make_evaluate_binop(
-                operator.div,
-                '__div__',
-                reversed=True,
-                step=operator.div)
+            cls.__div__ = _make_evaluate_binop(operator.div, step=operator.div)
+            cls.__rdiv__ = _make_evaluate_binop(ops.rdiv, step=ops.rdiv)
 
 
 RangeIndex._add_numeric_methods()

pandas/core/indexes/timedeltas.py

@@ -53,10 +53,11 @@ def f(self):
     return property(f)
 
 
-def _td_index_cmp(opname, cls, nat_result=False):
+def _td_index_cmp(opname, cls):
     """
     Wrap comparison operations to convert timedelta-like to timedelta64
     """
+    nat_result = True if opname == '__ne__' else False
 
     def wrapper(self, other):
         msg = "cannot compare a TimedeltaIndex with type {0}"
@@ -184,7 +185,7 @@ def _join_i8_wrapper(joinf, **kwargs):
     def _add_comparison_methods(cls):
         """ add in comparison methods """
         cls.__eq__ = _td_index_cmp('__eq__', cls)
-        cls.__ne__ = _td_index_cmp('__ne__', cls, nat_result=True)
+        cls.__ne__ = _td_index_cmp('__ne__', cls)
         cls.__lt__ = _td_index_cmp('__lt__', cls)
         cls.__gt__ = _td_index_cmp('__gt__', cls)
         cls.__le__ = _td_index_cmp('__le__', cls)
@@ -370,11 +371,12 @@ def _add_delta(self, delta):
         result = TimedeltaIndex(new_values, freq='infer', name=name)
         return result
 
-    def _evaluate_with_timedelta_like(self, other, op, opstr, reversed=False):
+    def _evaluate_with_timedelta_like(self, other, op):
         if isinstance(other, ABCSeries):
             # GH#19042
             return NotImplemented
 
+        opstr = '__{opname}__'.format(opname=op.__name__).replace('__r', '__')
         # allow division by a timedelta
         if opstr in ['__div__', '__truediv__', '__floordiv__']:
             if _is_convertible_to_td(other):
@@ -385,11 +387,9 @@ def _evaluate_with_timedelta_like(self, other, op, opstr, reversed=False):
 
                 i8 = self.asi8
                 left, right = i8, other.value
-                if reversed:
-                    left, right = right, left
 
                 if opstr in ['__floordiv__']:
-                    result = left // right
+                    result = op(left, right)
                 else:
                     result = op(left, np.float64(right))
                 result = self._maybe_mask_results(result, convert='float64')

pandas/tests/indexes/common.py

@@ -127,16 +127,17 @@ def test_numeric_compat(self):
         idx = self.create_index()
         tm.assert_raises_regex(TypeError, "cannot perform __mul__",
                                lambda: idx * 1)
-        tm.assert_raises_regex(TypeError, "cannot perform __mul__",
+        tm.assert_raises_regex(TypeError, "cannot perform __rmul__",
                                lambda: 1 * idx)
 
         div_err = "cannot perform __truediv__" if PY3 \
             else "cannot perform __div__"
         tm.assert_raises_regex(TypeError, div_err, lambda: idx / 1)
+        div_err = div_err.replace(' __', ' __r')
         tm.assert_raises_regex(TypeError, div_err, lambda: 1 / idx)
         tm.assert_raises_regex(TypeError, "cannot perform __floordiv__",
                                lambda: idx // 1)
-        tm.assert_raises_regex(TypeError, "cannot perform __floordiv__",
+        tm.assert_raises_regex(TypeError, "cannot perform __rfloordiv__",
                                lambda: 1 // idx)
 
     def test_logical_compat(self):

pandas/tests/indexes/test_base.py

@@ -7,6 +7,7 @@
 from collections import defaultdict
 
 import pandas.util.testing as tm
+from pandas.core.dtypes.generic import ABCIndex
 from pandas.core.dtypes.common import is_unsigned_integer_dtype
 from pandas.core.indexes.api import Index, MultiIndex
 from pandas.tests.indexes.common import Base
@@ -1988,6 +1989,17 @@ def test_addsub_arithmetic(self, dtype, delta):
         tm.assert_index_equal(idx - idx, 0 * idx)
         assert not (idx - idx).empty
 
+    def test_iadd_preserves_name(self):
+        # GH#17067, GH#19723 __iadd__ and __isub__ should preserve index name
+        ser = pd.Series([1, 2, 3])
+        ser.index.name = 'foo'
+
+        ser.index += 1
+        assert ser.index.name == "foo"
+
+        ser.index -= 1
+        assert ser.index.name == "foo"
+
 
 class TestMixedIntIndex(Base):
     # Mostly the tests from common.py for which the results differ
@@ -2301,9 +2313,17 @@ def test_ensure_index_from_sequences(self, data, names, expected):
         tm.assert_index_equal(result, expected)
 
 
-@pytest.mark.parametrize('opname', ['eq', 'ne', 'le', 'lt', 'ge', 'gt'])
+@pytest.mark.parametrize('opname', ['eq', 'ne', 'le', 'lt', 'ge', 'gt',
+                                    'add', 'radd', 'sub', 'rsub',
+                                    'mul', 'rmul', 'truediv', 'rtruediv',
+                                    'floordiv', 'rfloordiv',
+                                    'pow', 'rpow', 'mod', 'divmod'])
 def test_generated_op_names(opname, indices):
     index = indices
+    if isinstance(index, ABCIndex) and opname == 'rsub':
+        # pd.Index.__rsub__ does not exist; though the method does exist
+        # for subclasses.  see GH#19723
+        return
     opname = '__{name}__'.format(name=opname)
     method = getattr(index, opname)
     assert method.__name__ == opname