test_operators.py

# coding=utf-8
# pylint: disable-msg=E1101,W0612

import pytest
import pytz

from collections import Iterable
from datetime import datetime, timedelta
import operator
from itertools import product, starmap

from numpy import nan, inf
import numpy as np
import pandas as pd

from pandas import (Index, Series, DataFrame, isna, bdate_range,
                    NaT, date_range, timedelta_range, Categorical)
from pandas.core.indexes.datetimes import Timestamp
from pandas.core.indexes.timedeltas import Timedelta
import pandas.core.nanops as nanops

from pandas.compat import range, zip
from pandas import compat
from pandas.util.testing import (assert_series_equal, assert_almost_equal,
                                 assert_frame_equal, assert_index_equal)
import pandas.util.testing as tm

from .common import TestData


class TestSeriesComparisons(object):
    def test_series_comparison_scalars(self):
        series = Series(date_range('1/1/2000', periods=10))

        val = datetime(2000, 1, 4)
        result = series > val
        expected = Series([x > val for x in series])
        tm.assert_series_equal(result, expected)

        val = series[5]
        result = series > val
        expected = Series([x > val for x in series])
        tm.assert_series_equal(result, expected)

    def test_comparisons(self):
        left = np.random.randn(10)
        right = np.random.randn(10)
        left[:3] = np.nan

        result = nanops.nangt(left, right)
        with np.errstate(invalid='ignore'):
            expected = (left > right).astype('O')
        expected[:3] = np.nan

        assert_almost_equal(result, expected)

        s = Series(['a', 'b', 'c'])
        s2 = Series([False, True, False])

        # it works!
        exp = Series([False, False, False])
        assert_series_equal(s == s2, exp)
        assert_series_equal(s2 == s, exp)

    def test_operator_series_comparison_zerorank(self):
        # GH 13006
        result = np.float64(0) > pd.Series([1, 2, 3])
        expected = 0.0 > pd.Series([1, 2, 3])
        tm.assert_series_equal(result, expected)
        result = pd.Series([1, 2, 3]) < np.float64(0)
        expected = pd.Series([1, 2, 3]) < 0.0
        tm.assert_series_equal(result, expected)
        result = np.array([0, 1, 2])[0] > pd.Series([0, 1, 2])
        expected = 0.0 > pd.Series([1, 2, 3])
        tm.assert_series_equal(result, expected)

    def test_object_comparisons(self):
        s = Series(['a', 'b', np.nan, 'c', 'a'])

        result = s == 'a'
        expected = Series([True, False, False, False, True])
        assert_series_equal(result, expected)

        result = s < 'a'
        expected = Series([False, False, False, False, False])
        assert_series_equal(result, expected)

        result = s != 'a'
        expected = -(s == 'a')
        assert_series_equal(result, expected)

    def test_categorical_comparisons(self):
        # GH 8938
        # allow equality comparisons
        a = Series(list('abc'), dtype="category")
        b = Series(list('abc'), dtype="object")
        c = Series(['a', 'b', 'cc'], dtype="object")
        d = Series(list('acb'), dtype="object")
        e = Categorical(list('abc'))
        f = Categorical(list('acb'))

        # vs scalar
        assert not (a == 'a').all()
        assert ((a != 'a') == ~(a == 'a')).all()

        assert not ('a' == a).all()
        assert (a == 'a')[0]
        assert ('a' == a)[0]
        assert not ('a' != a)[0]

        # vs list-like
        assert (a == a).all()
        assert not (a != a).all()

        assert (a == list(a)).all()
        assert (a == b).all()
        assert (b == a).all()
        assert ((~(a == b)) == (a != b)).all()
        assert ((~(b == a)) == (b != a)).all()

        assert not (a == c).all()
        assert not (c == a).all()
        assert not (a == d).all()
        assert not (d == a).all()

        # vs a cat-like
        assert (a == e).all()
        assert (e == a).all()
        assert not (a == f).all()
        assert not (f == a).all()

        assert ((~(a == e) == (a != e)).all())
        assert ((~(e == a) == (e != a)).all())
        assert ((~(a == f) == (a != f)).all())
        assert ((~(f == a) == (f != a)).all())

        # non-equality is not comparable
        pytest.raises(TypeError, lambda: a < b)
        pytest.raises(TypeError, lambda: b < a)
        pytest.raises(TypeError, lambda: a > b)
        pytest.raises(TypeError, lambda: b > a)

    def test_comparison_tuples(self):
        # GH11339
        # comparisons vs tuple
        s = Series([(1, 1), (1, 2)])

        result = s == (1, 2)
        expected = Series([False, True])
        assert_series_equal(result, expected)

        result = s != (1, 2)
        expected = Series([True, False])
        assert_series_equal(result, expected)

        result = s == (0, 0)
        expected = Series([False, False])
        assert_series_equal(result, expected)

        result = s != (0, 0)
        expected = Series([True, True])
        assert_series_equal(result, expected)

        s = Series([(1, 1), (1, 1)])

        result = s == (1, 1)
        expected = Series([True, True])
        assert_series_equal(result, expected)

        result = s != (1, 1)
        expected = Series([False, False])
        assert_series_equal(result, expected)

        s = Series([frozenset([1]), frozenset([1, 2])])

        result = s == frozenset([1])
        expected = Series([True, False])
        assert_series_equal(result, expected)

    def test_comparison_operators_with_nas(self):
        s = Series(bdate_range('1/1/2000', periods=10), dtype=object)
        s[::2] = np.nan

        # test that comparisons work
        ops = ['lt', 'le', 'gt', 'ge', 'eq', 'ne']
        for op in ops:
            val = s[5]

            f = getattr(operator, op)
            result = f(s, val)

            expected = f(s.dropna(), val).reindex(s.index)

            if op == 'ne':
                expected = expected.fillna(True).astype(bool)
            else:
                expected = expected.fillna(False).astype(bool)

            assert_series_equal(result, expected)

            # fffffffuuuuuuuuuuuu
            # result = f(val, s)
            # expected = f(val, s.dropna()).reindex(s.index)
            # assert_series_equal(result, expected)

            # boolean &, |, ^ should work with object arrays and propagate NAs

        ops = ['and_', 'or_', 'xor']
        mask = s.isna()
        for bool_op in ops:
            f = getattr(operator, bool_op)

            filled = s.fillna(s[0])

            result = f(s < s[9], s > s[3])

            expected = f(filled < filled[9], filled > filled[3])
            expected[mask] = False
            assert_series_equal(result, expected)

    def test_comparison_object_numeric_nas(self):
        s = Series(np.random.randn(10), dtype=object)
        shifted = s.shift(2)

        ops = ['lt', 'le', 'gt', 'ge', 'eq', 'ne']
        for op in ops:
            f = getattr(operator, op)

            result = f(s, shifted)
            expected = f(s.astype(float), shifted.astype(float))
            assert_series_equal(result, expected)

    def test_comparison_invalid(self):
        # GH4968
        # invalid date/int comparisons
        s = Series(range(5))
        s2 = Series(date_range('20010101', periods=5))

        for (x, y) in [(s, s2), (s2, s)]:
            pytest.raises(TypeError, lambda: x == y)
            pytest.raises(TypeError, lambda: x != y)
            pytest.raises(TypeError, lambda: x >= y)
            pytest.raises(TypeError, lambda: x > y)
            pytest.raises(TypeError, lambda: x < y)
            pytest.raises(TypeError, lambda: x <= y)

    def test_unequal_categorical_comparison_raises_type_error(self):
        # unequal comparison should raise for unordered cats
        cat = Series(Categorical(list("abc")))

        def f():
            cat > "b"

        pytest.raises(TypeError, f)
        cat = Series(Categorical(list("abc"), ordered=False))

        def f():
            cat > "b"

        pytest.raises(TypeError, f)

        # https://github.com/pandas-dev/pandas/issues/9836#issuecomment-92123057
        # and following comparisons with scalars not in categories should raise
        # for unequal comps, but not for equal/not equal
        cat = Series(Categorical(list("abc"), ordered=True))

        pytest.raises(TypeError, lambda: cat < "d")
        pytest.raises(TypeError, lambda: cat > "d")
        pytest.raises(TypeError, lambda: "d" < cat)
        pytest.raises(TypeError, lambda: "d" > cat)

        tm.assert_series_equal(cat == "d", Series([False, False, False]))
        tm.assert_series_equal(cat != "d", Series([True, True, True]))

    def test_more_na_comparisons(self):
        for dtype in [None, object]:
            left = Series(['a', np.nan, 'c'], dtype=dtype)
            right = Series(['a', np.nan, 'd'], dtype=dtype)

            result = left == right
            expected = Series([True, False, False])
            assert_series_equal(result, expected)

            result = left != right
            expected = Series([False, True, True])
            assert_series_equal(result, expected)

            result = left == np.nan
            expected = Series([False, False, False])
            assert_series_equal(result, expected)

            result = left != np.nan
            expected = Series([True, True, True])
            assert_series_equal(result, expected)

    def test_nat_comparisons(self):
        data = [([pd.Timestamp('2011-01-01'), pd.NaT,
                  pd.Timestamp('2011-01-03')],
                 [pd.NaT, pd.NaT, pd.Timestamp('2011-01-03')]),

                ([pd.Timedelta('1 days'), pd.NaT,
                  pd.Timedelta('3 days')],
                 [pd.NaT, pd.NaT, pd.Timedelta('3 days')]),

                ([pd.Period('2011-01', freq='M'), pd.NaT,
                  pd.Period('2011-03', freq='M')],
                 [pd.NaT, pd.NaT, pd.Period('2011-03', freq='M')])]

        # add lhs / rhs switched data
        data = data + [(r, l) for l, r in data]

        for l, r in data:
            for dtype in [None, object]:
                left = Series(l, dtype=dtype)

                # Series, Index
                for right in [Series(r, dtype=dtype), Index(r, dtype=dtype)]:
                    expected = Series([False, False, True])
                    assert_series_equal(left == right, expected)

                    expected = Series([True, True, False])
                    assert_series_equal(left != right, expected)

                    expected = Series([False, False, False])
                    assert_series_equal(left < right, expected)

                    expected = Series([False, False, False])
                    assert_series_equal(left > right, expected)

                    expected = Series([False, False, True])
                    assert_series_equal(left >= right, expected)

                    expected = Series([False, False, True])
                    assert_series_equal(left <= right, expected)

    def test_nat_comparisons_scalar(self):
        data = [[pd.Timestamp('2011-01-01'), pd.NaT,
                 pd.Timestamp('2011-01-03')],

                [pd.Timedelta('1 days'), pd.NaT, pd.Timedelta('3 days')],

                [pd.Period('2011-01', freq='M'), pd.NaT,
                 pd.Period('2011-03', freq='M')]]

        for l in data:
            for dtype in [None, object]:
                left = Series(l, dtype=dtype)

                expected = Series([False, False, False])
                assert_series_equal(left == pd.NaT, expected)
                assert_series_equal(pd.NaT == left, expected)

                expected = Series([True, True, True])
                assert_series_equal(left != pd.NaT, expected)
                assert_series_equal(pd.NaT != left, expected)

                expected = Series([False, False, False])
                assert_series_equal(left < pd.NaT, expected)
                assert_series_equal(pd.NaT > left, expected)
                assert_series_equal(left <= pd.NaT, expected)
                assert_series_equal(pd.NaT >= left, expected)

                assert_series_equal(left > pd.NaT, expected)
                assert_series_equal(pd.NaT < left, expected)
                assert_series_equal(left >= pd.NaT, expected)
                assert_series_equal(pd.NaT <= left, expected)

    def test_comparison_different_length(self):
        a = Series(['a', 'b', 'c'])
        b = Series(['b', 'a'])
        pytest.raises(ValueError, a.__lt__, b)

        a = Series([1, 2])
        b = Series([2, 3, 4])
        pytest.raises(ValueError, a.__eq__, b)

    def test_comparison_label_based(self):

        # GH 4947
        # comparisons should be label based

        a = Series([True, False, True], list('bca'))
        b = Series([False, True, False], list('abc'))

        expected = Series([False, True, False], list('abc'))
        result = a & b
        assert_series_equal(result, expected)

        expected = Series([True, True, False], list('abc'))
        result = a | b
        assert_series_equal(result, expected)

        expected = Series([True, False, False], list('abc'))
        result = a ^ b
        assert_series_equal(result, expected)

        # rhs is bigger
        a = Series([True, False, True], list('bca'))
        b = Series([False, True, False, True], list('abcd'))

        expected = Series([False, True, False, False], list('abcd'))
        result = a & b
        assert_series_equal(result, expected)

        expected = Series([True, True, False, False], list('abcd'))
        result = a | b
        assert_series_equal(result, expected)

        # filling

        # vs empty
        result = a & Series([])
        expected = Series([False, False, False], list('bca'))
        assert_series_equal(result, expected)

        result = a | Series([])
        expected = Series([True, False, True], list('bca'))
        assert_series_equal(result, expected)

        # vs non-matching
        result = a & Series([1], ['z'])
        expected = Series([False, False, False, False], list('abcz'))
        assert_series_equal(result, expected)

        result = a | Series([1], ['z'])
        expected = Series([True, True, False, False], list('abcz'))
        assert_series_equal(result, expected)

        # identity
        # we would like s[s|e] == s to hold for any e, whether empty or not
        for e in [Series([]), Series([1], ['z']),
                  Series(np.nan, b.index), Series(np.nan, a.index)]:
            result = a[a | e]
            assert_series_equal(result, a[a])

        for e in [Series(['z'])]:
            if compat.PY3:
                with tm.assert_produces_warning(RuntimeWarning):
                    result = a[a | e]
            else:
                result = a[a | e]
            assert_series_equal(result, a[a])

        # vs scalars
        index = list('bca')
        t = Series([True, False, True])

        for v in [True, 1, 2]:
            result = Series([True, False, True], index=index) | v
            expected = Series([True, True, True], index=index)
            assert_series_equal(result, expected)

        for v in [np.nan, 'foo']:
            pytest.raises(TypeError, lambda: t | v)

        for v in [False, 0]:
            result = Series([True, False, True], index=index) | v
            expected = Series([True, False, True], index=index)
            assert_series_equal(result, expected)

        for v in [True, 1]:
            result = Series([True, False, True], index=index) & v
            expected = Series([True, False, True], index=index)
            assert_series_equal(result, expected)

        for v in [False, 0]:
            result = Series([True, False, True], index=index) & v
            expected = Series([False, False, False], index=index)
            assert_series_equal(result, expected)
        for v in [np.nan]:
            pytest.raises(TypeError, lambda: t & v)

    def test_comparison_flex_basic(self):
        left = pd.Series(np.random.randn(10))
        right = pd.Series(np.random.randn(10))

        assert_series_equal(left.eq(right), left == right)
        assert_series_equal(left.ne(right), left != right)
        assert_series_equal(left.le(right), left < right)
        assert_series_equal(left.lt(right), left <= right)
        assert_series_equal(left.gt(right), left > right)
        assert_series_equal(left.ge(right), left >= right)

        # axis
        for axis in [0, None, 'index']:
            assert_series_equal(left.eq(right, axis=axis), left == right)
            assert_series_equal(left.ne(right, axis=axis), left != right)
            assert_series_equal(left.le(right, axis=axis), left < right)
            assert_series_equal(left.lt(right, axis=axis), left <= right)
            assert_series_equal(left.gt(right, axis=axis), left > right)
            assert_series_equal(left.ge(right, axis=axis), left >= right)

        #
        msg = 'No axis named 1 for object type'
        for op in ['eq', 'ne', 'le', 'le', 'gt', 'ge']:
            with tm.assert_raises_regex(ValueError, msg):
                getattr(left, op)(right, axis=1)

    def test_comparison_flex_alignment(self):
        left = Series([1, 3, 2], index=list('abc'))
        right = Series([2, 2, 2], index=list('bcd'))

        exp = pd.Series([False, False, True, False], index=list('abcd'))
        assert_series_equal(left.eq(right), exp)

        exp = pd.Series([True, True, False, True], index=list('abcd'))
        assert_series_equal(left.ne(right), exp)

        exp = pd.Series([False, False, True, False], index=list('abcd'))
        assert_series_equal(left.le(right), exp)

        exp = pd.Series([False, False, False, False], index=list('abcd'))
        assert_series_equal(left.lt(right), exp)

        exp = pd.Series([False, True, True, False], index=list('abcd'))
        assert_series_equal(left.ge(right), exp)

        exp = pd.Series([False, True, False, False], index=list('abcd'))
        assert_series_equal(left.gt(right), exp)

    def test_comparison_flex_alignment_fill(self):
        left = Series([1, 3, 2], index=list('abc'))
        right = Series([2, 2, 2], index=list('bcd'))

        exp = pd.Series([False, False, True, True], index=list('abcd'))
        assert_series_equal(left.eq(right, fill_value=2), exp)

        exp = pd.Series([True, True, False, False], index=list('abcd'))
        assert_series_equal(left.ne(right, fill_value=2), exp)

        exp = pd.Series([False, False, True, True], index=list('abcd'))
        assert_series_equal(left.le(right, fill_value=0), exp)

        exp = pd.Series([False, False, False, True], index=list('abcd'))
        assert_series_equal(left.lt(right, fill_value=0), exp)

        exp = pd.Series([True, True, True, False], index=list('abcd'))
        assert_series_equal(left.ge(right, fill_value=0), exp)

        exp = pd.Series([True, True, False, False], index=list('abcd'))
        assert_series_equal(left.gt(right, fill_value=0), exp)

    def test_ne(self):
        ts = Series([3, 4, 5, 6, 7], [3, 4, 5, 6, 7], dtype=float)
        expected = [True, True, False, True, True]
        assert tm.equalContents(ts.index != 5, expected)
        assert tm.equalContents(~(ts.index == 5), expected)

    def test_comp_ops_df_compat(self):
        # GH 1134
        s1 = pd.Series([1, 2, 3], index=list('ABC'), name='x')
        s2 = pd.Series([2, 2, 2], index=list('ABD'), name='x')

        s3 = pd.Series([1, 2, 3], index=list('ABC'), name='x')
        s4 = pd.Series([2, 2, 2, 2], index=list('ABCD'), name='x')

        for l, r in [(s1, s2), (s2, s1), (s3, s4), (s4, s3)]:

            msg = "Can only compare identically-labeled Series objects"
            with tm.assert_raises_regex(ValueError, msg):
                l == r

            with tm.assert_raises_regex(ValueError, msg):
                l != r

            with tm.assert_raises_regex(ValueError, msg):
                l < r

            msg = "Can only compare identically-labeled DataFrame objects"
            with tm.assert_raises_regex(ValueError, msg):
                l.to_frame() == r.to_frame()

            with tm.assert_raises_regex(ValueError, msg):
                l.to_frame() != r.to_frame()

            with tm.assert_raises_regex(ValueError, msg):
                l.to_frame() < r.to_frame()


class TestSeriesArithmetic(object):
    def test_divide_decimal(self):
        """ resolves issue #9787 """
        from decimal import Decimal

        expected = Series([Decimal(5)])

        s = Series([Decimal(10)])
        s = s / Decimal(2)

        assert_series_equal(expected, s)

        s = Series([Decimal(10)])
        s = s // Decimal(2)

        assert_series_equal(expected, s)

    def test_div(self):
        with np.errstate(all='ignore'):
            # no longer do integer div for any ops, but deal with the 0's
            p = DataFrame({'first': [3, 4, 5, 8], 'second': [0, 0, 0, 3]})
            result = p['first'] / p['second']
            expected = Series(
                p['first'].values.astype(float) / p['second'].values,
                dtype='float64')
            expected.iloc[0:3] = np.inf
            assert_series_equal(result, expected)

            result = p['first'] / 0
            expected = Series(np.inf, index=p.index, name='first')
            assert_series_equal(result, expected)

            p = p.astype('float64')
            result = p['first'] / p['second']
            expected = Series(p['first'].values / p['second'].values)
            assert_series_equal(result, expected)

            p = DataFrame({'first': [3, 4, 5, 8], 'second': [1, 1, 1, 1]})
            result = p['first'] / p['second']
            assert_series_equal(result, p['first'].astype('float64'),
                                check_names=False)
            assert result.name is None
            assert not result.equals(p['second'] / p['first'])

            # inf signing
            s = Series([np.nan, 1., -1.])
            result = s / 0
            expected = Series([np.nan, np.inf, -np.inf])
            assert_series_equal(result, expected)

            # float/integer issue
            # GH 7785
            p = DataFrame({'first': (1, 0), 'second': (-0.01, -0.02)})
            expected = Series([-0.01, -np.inf])

            result = p['second'].div(p['first'])
            assert_series_equal(result, expected, check_names=False)

            result = p['second'] / p['first']
            assert_series_equal(result, expected)

            # GH 9144
            s = Series([-1, 0, 1])

            result = 0 / s
            expected = Series([0.0, nan, 0.0])
            assert_series_equal(result, expected)

            result = s / 0
            expected = Series([-inf, nan, inf])
            assert_series_equal(result, expected)

            result = s // 0
            expected = Series([-inf, nan, inf])
            assert_series_equal(result, expected)

            # GH 8674
            zero_array = np.array([0] * 5)
            data = np.random.randn(5)
            expected = pd.Series([0.] * 5)
            result = zero_array / pd.Series(data)
            assert_series_equal(result, expected)

            result = pd.Series(zero_array) / data
            assert_series_equal(result, expected)

            result = pd.Series(zero_array) / pd.Series(data)
            assert_series_equal(result, expected)


class TestTimedeltaSeriesArithmetic(object):
    def test_timedelta_series_ops(self):
        # GH11925
        s = Series(timedelta_range('1 day', periods=3))
        ts = Timestamp('2012-01-01')
        expected = Series(date_range('2012-01-02', periods=3))
        assert_series_equal(ts + s, expected)
        assert_series_equal(s + ts, expected)

        expected2 = Series(date_range('2011-12-31', periods=3, freq='-1D'))
        assert_series_equal(ts - s, expected2)
        assert_series_equal(ts + (-s), expected2)

    def test_timedelta64_operations_with_integers(self):
        # GH 4521
        # divide/multiply by integers
        startdate = Series(date_range('2013-01-01', '2013-01-03'))
        enddate = Series(date_range('2013-03-01', '2013-03-03'))

        s1 = enddate - startdate
        s1[2] = np.nan
        s2 = Series([2, 3, 4])
        expected = Series(s1.values.astype(np.int64) / s2, dtype='m8[ns]')
        expected[2] = np.nan
        result = s1 / s2
        assert_series_equal(result, expected)

        s2 = Series([20, 30, 40])
        expected = Series(s1.values.astype(np.int64) / s2, dtype='m8[ns]')
        expected[2] = np.nan
        result = s1 / s2
        assert_series_equal(result, expected)

        result = s1 / 2
        expected = Series(s1.values.astype(np.int64) / 2, dtype='m8[ns]')
        expected[2] = np.nan
        assert_series_equal(result, expected)

        s2 = Series([20, 30, 40])
        expected = Series(s1.values.astype(np.int64) * s2, dtype='m8[ns]')
        expected[2] = np.nan
        result = s1 * s2
        assert_series_equal(result, expected)

        for dtype in ['int32', 'int16', 'uint32', 'uint64', 'uint32', 'uint16',
                      'uint8']:
            s2 = Series([20, 30, 40], dtype=dtype)
            expected = Series(
                s1.values.astype(np.int64) * s2.astype(np.int64),
                dtype='m8[ns]')
            expected[2] = np.nan
            result = s1 * s2
            assert_series_equal(result, expected)

        result = s1 * 2
        expected = Series(s1.values.astype(np.int64) * 2, dtype='m8[ns]')
        expected[2] = np.nan
        assert_series_equal(result, expected)

        result = s1 * -1
        expected = Series(s1.values.astype(np.int64) * -1, dtype='m8[ns]')
        expected[2] = np.nan
        assert_series_equal(result, expected)

        # invalid ops
        assert_series_equal(s1 / s2.astype(float),
                            Series([Timedelta('2 days 22:48:00'), Timedelta(
                                '1 days 23:12:00'), Timedelta('NaT')]))
        assert_series_equal(s1 / 2.0,
                            Series([Timedelta('29 days 12:00:00'), Timedelta(
                                '29 days 12:00:00'), Timedelta('NaT')]))

        for op in ['__add__', '__sub__']:
            sop = getattr(s1, op, None)
            if sop is not None:
                pytest.raises(TypeError, sop, 1)
                pytest.raises(TypeError, sop, s2.values)

    def test_timedelta64_operations_with_DateOffset(self):
        # GH 10699
        td = Series([timedelta(minutes=5, seconds=3)] * 3)
        result = td + pd.offsets.Minute(1)
        expected = Series([timedelta(minutes=6, seconds=3)] * 3)
        assert_series_equal(result, expected)

        result = td - pd.offsets.Minute(1)
        expected = Series([timedelta(minutes=4, seconds=3)] * 3)
        assert_series_equal(result, expected)

        result = td + Series([pd.offsets.Minute(1), pd.offsets.Second(3),
                              pd.offsets.Hour(2)])
        expected = Series([timedelta(minutes=6, seconds=3), timedelta(
            minutes=5, seconds=6), timedelta(hours=2, minutes=5, seconds=3)])
        assert_series_equal(result, expected)

        result = td + pd.offsets.Minute(1) + pd.offsets.Second(12)
        expected = Series([timedelta(minutes=6, seconds=15)] * 3)
        assert_series_equal(result, expected)

        # valid DateOffsets
        for do in ['Hour', 'Minute', 'Second', 'Day', 'Micro', 'Milli',
                   'Nano']:
            op = getattr(pd.offsets, do)
            td + op(5)
            op(5) + td
            td - op(5)
            op(5) - td

    def test_timedelta64_operations_with_timedeltas(self):
        # td operate with td
        td1 = Series([timedelta(minutes=5, seconds=3)] * 3)
        td2 = timedelta(minutes=5, seconds=4)
        result = td1 - td2
        expected = (Series([timedelta(seconds=0)] * 3) -
                    Series([timedelta(seconds=1)] * 3))
        assert result.dtype == 'm8[ns]'
        assert_series_equal(result, expected)

        result2 = td2 - td1
        expected = (Series([timedelta(seconds=1)] * 3) -
                    Series([timedelta(seconds=0)] * 3))
        assert_series_equal(result2, expected)

        # roundtrip
        assert_series_equal(result + td2, td1)

        # Now again, using pd.to_timedelta, which should build
        # a Series or a scalar, depending on input.
        td1 = Series(pd.to_timedelta(['00:05:03'] * 3))
        td2 = pd.to_timedelta('00:05:04')
        result = td1 - td2
        expected = (Series([timedelta(seconds=0)] * 3) -
                    Series([timedelta(seconds=1)] * 3))
        assert result.dtype == 'm8[ns]'
        assert_series_equal(result, expected)

        result2 = td2 - td1
        expected = (Series([timedelta(seconds=1)] * 3) -
                    Series([timedelta(seconds=0)] * 3))
        assert_series_equal(result2, expected)

        # roundtrip
        assert_series_equal(result + td2, td1)

    def test_operators_timedelta64(self):
        # series ops
        v1 = date_range('2012-1-1', periods=3, freq='D')
        v2 = date_range('2012-1-2', periods=3, freq='D')
        rs = Series(v2) - Series(v1)
        xp = Series(1e9 * 3600 * 24,
                    rs.index).astype('int64').astype('timedelta64[ns]')
        assert_series_equal(rs, xp)
        assert rs.dtype == 'timedelta64[ns]'

        df = DataFrame(dict(A=v1))
        td = Series([timedelta(days=i) for i in range(3)])
        assert td.dtype == 'timedelta64[ns]'

        # series on the rhs
        result = df['A'] - df['A'].shift()
        assert result.dtype == 'timedelta64[ns]'

        result = df['A'] + td
        assert result.dtype == 'M8[ns]'

        # scalar Timestamp on rhs
        maxa = df['A'].max()
        assert isinstance(maxa, Timestamp)

        resultb = df['A'] - df['A'].max()
        assert resultb.dtype == 'timedelta64[ns]'

        # timestamp on lhs
        result = resultb + df['A']
        values = [Timestamp('20111230'), Timestamp('20120101'),
                  Timestamp('20120103')]
        expected = Series(values, name='A')
        assert_series_equal(result, expected)

        # datetimes on rhs
        result = df['A'] - datetime(2001, 1, 1)
        expected = Series(
            [timedelta(days=4017 + i) for i in range(3)], name='A')
        assert_series_equal(result, expected)
        assert result.dtype == 'm8[ns]'

        d = datetime(2001, 1, 1, 3, 4)
        resulta = df['A'] - d
        assert resulta.dtype == 'm8[ns]'

        # roundtrip
        resultb = resulta + d
        assert_series_equal(df['A'], resultb)

        # timedeltas on rhs
        td = timedelta(days=1)
        resulta = df['A'] + td
        resultb = resulta - td
        assert_series_equal(resultb, df['A'])
        assert resultb.dtype == 'M8[ns]'

        # roundtrip
        td = timedelta(minutes=5, seconds=3)
        resulta = df['A'] + td
        resultb = resulta - td
        assert_series_equal(df['A'], resultb)
        assert resultb.dtype == 'M8[ns]'

        # inplace
        value = rs[2] + np.timedelta64(timedelta(minutes=5, seconds=1))
        rs[2] += np.timedelta64(timedelta(minutes=5, seconds=1))
        assert rs[2] == value

    def test_timedelta64_ops_nat(self):
        # GH 11349
        timedelta_series = Series([NaT, Timedelta('1s')])
        nat_series_dtype_timedelta = Series([NaT, NaT],
                                            dtype='timedelta64[ns]')
        single_nat_dtype_timedelta = Series([NaT], dtype='timedelta64[ns]')

        # subtraction
        assert_series_equal(timedelta_series - NaT,
                            nat_series_dtype_timedelta)
        assert_series_equal(-NaT + timedelta_series,
                            nat_series_dtype_timedelta)

        assert_series_equal(timedelta_series - single_nat_dtype_timedelta,
                            nat_series_dtype_timedelta)
        assert_series_equal(-single_nat_dtype_timedelta + timedelta_series,
                            nat_series_dtype_timedelta)

        # addition
        assert_series_equal(nat_series_dtype_timedelta + NaT,
                            nat_series_dtype_timedelta)
        assert_series_equal(NaT + nat_series_dtype_timedelta,
                            nat_series_dtype_timedelta)

        assert_series_equal(nat_series_dtype_timedelta +
                            single_nat_dtype_timedelta,
                            nat_series_dtype_timedelta)
        assert_series_equal(single_nat_dtype_timedelta +
                            nat_series_dtype_timedelta,
                            nat_series_dtype_timedelta)

        assert_series_equal(timedelta_series + NaT,
                            nat_series_dtype_timedelta)
        assert_series_equal(NaT + timedelta_series,
                            nat_series_dtype_timedelta)

        assert_series_equal(timedelta_series + single_nat_dtype_timedelta,
                            nat_series_dtype_timedelta)
        assert_series_equal(single_nat_dtype_timedelta + timedelta_series,
                            nat_series_dtype_timedelta)

        assert_series_equal(nat_series_dtype_timedelta + NaT,
                            nat_series_dtype_timedelta)
        assert_series_equal(NaT + nat_series_dtype_timedelta,
                            nat_series_dtype_timedelta)

        assert_series_equal(nat_series_dtype_timedelta +
                            single_nat_dtype_timedelta,
                            nat_series_dtype_timedelta)
        assert_series_equal(single_nat_dtype_timedelta +
                            nat_series_dtype_timedelta,
                            nat_series_dtype_timedelta)

        # multiplication
        assert_series_equal(nat_series_dtype_timedelta * 1.0,
                            nat_series_dtype_timedelta)
        assert_series_equal(1.0 * nat_series_dtype_timedelta,
                            nat_series_dtype_timedelta)

        assert_series_equal(timedelta_series * 1, timedelta_series)
        assert_series_equal(1 * timedelta_series, timedelta_series)

        assert_series_equal(timedelta_series * 1.5,
                            Series([NaT, Timedelta('1.5s')]))
        assert_series_equal(1.5 * timedelta_series,
                            Series([NaT, Timedelta('1.5s')]))

        assert_series_equal(timedelta_series * nan,
                            nat_series_dtype_timedelta)
        assert_series_equal(nan * timedelta_series,
                            nat_series_dtype_timedelta)

        # division
        assert_series_equal(timedelta_series / 2,
                            Series([NaT, Timedelta('0.5s')]))
        assert_series_equal(timedelta_series / 2.0,
                            Series([NaT, Timedelta('0.5s')]))
        assert_series_equal(timedelta_series / nan,
                            nat_series_dtype_timedelta)

    @pytest.mark.parametrize('scalar_td', [timedelta(minutes=5, seconds=4),
                                           Timedelta(minutes=5, seconds=4),
                                           Timedelta('5m4s').to_timedelta64()])
    def test_operators_timedelta64_with_timedelta(self, scalar_td):
        # smoke tests
        td1 = Series([timedelta(minutes=5, seconds=3)] * 3)
        td1.iloc[2] = np.nan

        td1 + scalar_td
        scalar_td + td1
        td1 - scalar_td
        scalar_td - td1
        td1 / scalar_td
        scalar_td / td1

    @pytest.mark.parametrize('scalar_td', [
        timedelta(minutes=5, seconds=4),
        pytest.param(Timedelta('5m4s'),
                     marks=pytest.mark.xfail(reason="Timedelta.__floordiv__ "
                                                    "bug GH#18846")),
        Timedelta('5m4s').to_timedelta64()])
    def test_operators_timedelta64_with_timedelta_invalid(self, scalar_td):
        td1 = Series([timedelta(minutes=5, seconds=3)] * 3)
        td1.iloc[2] = np.nan

        # check that we are getting a TypeError
        # with 'operate' (from core/ops.py) for the ops that are not
        # defined
        pattern = 'operate|unsupported|cannot'
        with tm.assert_raises_regex(TypeError, pattern):
            td1 * scalar_td
        with tm.assert_raises_regex(TypeError, pattern):
            scalar_td * td1
        with tm.assert_raises_regex(TypeError, pattern):
            td1 // scalar_td
        with tm.assert_raises_regex(TypeError, pattern):
            scalar_td // td1
        with tm.assert_raises_regex(TypeError, pattern):
            scalar_td ** td1
        with tm.assert_raises_regex(TypeError, pattern):
            td1 ** scalar_td


class TestDatetimeSeriesArithmetic(object):

    def test_operators_datetimelike(self):
        def run_ops(ops, get_ser, test_ser):

            # check that we are getting a TypeError
            # with 'operate' (from core/ops.py) for the ops that are not
            # defined
            for op_str in ops:
                op = getattr(get_ser, op_str, None)
                with tm.assert_raises_regex(TypeError, 'operate'):
                    op(test_ser)

        # ## timedelta64 ###
        td1 = Series([timedelta(minutes=5, seconds=3)] * 3)
        td1.iloc[2] = np.nan

        # ## datetime64 ###
        dt1 = Series([Timestamp('20111230'), Timestamp('20120101'),
                      Timestamp('20120103')])
        dt1.iloc[2] = np.nan
        dt2 = Series([Timestamp('20111231'), Timestamp('20120102'),
                      Timestamp('20120104')])
        ops = ['__add__', '__mul__', '__floordiv__', '__truediv__', '__div__',
               '__pow__', '__radd__', '__rmul__', '__rfloordiv__',
               '__rtruediv__', '__rdiv__', '__rpow__']
        run_ops(ops, dt1, dt2)
        dt1 - dt2
        dt2 - dt1

        # ## datetime64 with timetimedelta ###
        ops = ['__mul__', '__floordiv__', '__truediv__', '__div__', '__pow__',
               '__rmul__', '__rfloordiv__', '__rtruediv__', '__rdiv__',
               '__rpow__']
        run_ops(ops, dt1, td1)
        dt1 + td1
        td1 + dt1
        dt1 - td1
        # TODO: Decide if this ought to work.
        # td1 - dt1

        # ## timetimedelta with datetime64 ###
        ops = ['__sub__', '__mul__', '__floordiv__', '__truediv__', '__div__',
               '__pow__', '__rmul__', '__rfloordiv__', '__rtruediv__',
               '__rdiv__', '__rpow__']
        run_ops(ops, td1, dt1)
        td1 + dt1
        dt1 + td1

        # 8260, 10763
        # datetime64 with tz
        ops = ['__mul__', '__floordiv__', '__truediv__', '__div__', '__pow__',
               '__rmul__', '__rfloordiv__', '__rtruediv__', '__rdiv__',
               '__rpow__']

        tz = 'US/Eastern'
        dt1 = Series(date_range('2000-01-01 09:00:00', periods=5,
                                tz=tz), name='foo')
        dt2 = dt1.copy()
        dt2.iloc[2] = np.nan
        td1 = Series(timedelta_range('1 days 1 min', periods=5, freq='H'))
        td2 = td1.copy()
        td2.iloc[1] = np.nan
        run_ops(ops, dt1, td1)

        result = dt1 + td1[0]
        exp = (dt1.dt.tz_localize(None) + td1[0]).dt.tz_localize(tz)
        assert_series_equal(result, exp)

        result = dt2 + td2[0]
        exp = (dt2.dt.tz_localize(None) + td2[0]).dt.tz_localize(tz)
        assert_series_equal(result, exp)

        # odd numpy behavior with scalar timedeltas
        result = td1[0] + dt1
        exp = (dt1.dt.tz_localize(None) + td1[0]).dt.tz_localize(tz)
        assert_series_equal(result, exp)

        result = td2[0] + dt2
        exp = (dt2.dt.tz_localize(None) + td2[0]).dt.tz_localize(tz)
        assert_series_equal(result, exp)

        result = dt1 - td1[0]
        exp = (dt1.dt.tz_localize(None) - td1[0]).dt.tz_localize(tz)
        assert_series_equal(result, exp)
        pytest.raises(TypeError, lambda: td1[0] - dt1)

        result = dt2 - td2[0]
        exp = (dt2.dt.tz_localize(None) - td2[0]).dt.tz_localize(tz)
        assert_series_equal(result, exp)
        pytest.raises(TypeError, lambda: td2[0] - dt2)

        result = dt1 + td1
        exp = (dt1.dt.tz_localize(None) + td1).dt.tz_localize(tz)
        assert_series_equal(result, exp)

        result = dt2 + td2
        exp = (dt2.dt.tz_localize(None) + td2).dt.tz_localize(tz)
        assert_series_equal(result, exp)

        result = dt1 - td1
        exp = (dt1.dt.tz_localize(None) - td1).dt.tz_localize(tz)
        assert_series_equal(result, exp)

        result = dt2 - td2
        exp = (dt2.dt.tz_localize(None) - td2).dt.tz_localize(tz)
        assert_series_equal(result, exp)

        pytest.raises(TypeError, lambda: td1 - dt1)
        pytest.raises(TypeError, lambda: td2 - dt2)

    def test_sub_single_tz(self):
        # GH12290
        s1 = Series([pd.Timestamp('2016-02-10', tz='America/Sao_Paulo')])
        s2 = Series([pd.Timestamp('2016-02-08', tz='America/Sao_Paulo')])
        result = s1 - s2
        expected = Series([Timedelta('2days')])
        assert_series_equal(result, expected)
        result = s2 - s1
        expected = Series([Timedelta('-2days')])
        assert_series_equal(result, expected)

    def test_sub_datetime_compat(self):
        # see gh-14088
        s = Series([datetime(2016, 8, 23, 12, tzinfo=pytz.utc), pd.NaT])
        dt = datetime(2016, 8, 22, 12, tzinfo=pytz.utc)
        exp = Series([Timedelta('1 days'), pd.NaT])
        assert_series_equal(s - dt, exp)
        assert_series_equal(s - Timestamp(dt), exp)

    def test_datetime_series_with_timedelta(self):
        # scalar timedeltas/np.timedelta64 objects
        # operate with np.timedelta64 correctly
        s = Series([Timestamp('20130101 9:01'), Timestamp('20130101 9:02')])

        result = s + np.timedelta64(1, 's')
        result2 = np.timedelta64(1, 's') + s
        expected = Series([Timestamp('20130101 9:01:01'),
                           Timestamp('20130101 9:02:01')])
        assert_series_equal(result, expected)
        assert_series_equal(result2, expected)

        result = s + np.timedelta64(5, 'ms')
        result2 = np.timedelta64(5, 'ms') + s
        expected = Series([Timestamp('20130101 9:01:00.005'),
                           Timestamp('20130101 9:02:00.005')])
        assert_series_equal(result, expected)
        assert_series_equal(result2, expected)

    def test_datetime_series_with_DateOffset(self):
        # GH 4532
        # operate with pd.offsets
        s = Series([Timestamp('20130101 9:01'), Timestamp('20130101 9:02')])

        result = s + pd.offsets.Second(5)
        result2 = pd.offsets.Second(5) + s
        expected = Series([Timestamp('20130101 9:01:05'),
                           Timestamp('20130101 9:02:05')])
        assert_series_equal(result, expected)
        assert_series_equal(result2, expected)

        result = s - pd.offsets.Second(5)
        result2 = -pd.offsets.Second(5) + s
        expected = Series([Timestamp('20130101 9:00:55'),
                           Timestamp('20130101 9:01:55')])
        assert_series_equal(result, expected)
        assert_series_equal(result2, expected)

        result = s + pd.offsets.Milli(5)
        result2 = pd.offsets.Milli(5) + s
        expected = Series([Timestamp('20130101 9:01:00.005'),
                           Timestamp('20130101 9:02:00.005')])
        assert_series_equal(result, expected)
        assert_series_equal(result2, expected)

        result = s + pd.offsets.Minute(5) + pd.offsets.Milli(5)
        expected = Series([Timestamp('20130101 9:06:00.005'),
                           Timestamp('20130101 9:07:00.005')])
        assert_series_equal(result, expected)

        # valid DateOffsets
        for do in ['Hour', 'Minute', 'Second', 'Day', 'Micro', 'Milli',
                   'Nano']:
            op = getattr(pd.offsets, do)
            s + op(5)
            op(5) + s

    def test_datetime64_ops_nat(self):
        # GH 11349
        datetime_series = Series([NaT, Timestamp('19900315')])
        nat_series_dtype_timestamp = Series([NaT, NaT], dtype='datetime64[ns]')
        single_nat_dtype_datetime = Series([NaT], dtype='datetime64[ns]')

        # subtraction
        assert_series_equal(datetime_series - NaT, nat_series_dtype_timestamp)
        assert_series_equal(-NaT + datetime_series, nat_series_dtype_timestamp)
        with pytest.raises(TypeError):
            -single_nat_dtype_datetime + datetime_series

        assert_series_equal(nat_series_dtype_timestamp - NaT,
                            nat_series_dtype_timestamp)
        assert_series_equal(-NaT + nat_series_dtype_timestamp,
                            nat_series_dtype_timestamp)
        with pytest.raises(TypeError):
            -single_nat_dtype_datetime + nat_series_dtype_timestamp

        # addition
        assert_series_equal(nat_series_dtype_timestamp + NaT,
                            nat_series_dtype_timestamp)
        assert_series_equal(NaT + nat_series_dtype_timestamp,
                            nat_series_dtype_timestamp)

        assert_series_equal(nat_series_dtype_timestamp + NaT,
                            nat_series_dtype_timestamp)
        assert_series_equal(NaT + nat_series_dtype_timestamp,
                            nat_series_dtype_timestamp)

        # multiplication
        with pytest.raises(TypeError):
            datetime_series * 1
        with pytest.raises(TypeError):
            nat_series_dtype_timestamp * 1
        with pytest.raises(TypeError):
            datetime_series * 1.0
        with pytest.raises(TypeError):
            nat_series_dtype_timestamp * 1.0

        # division
        with pytest.raises(TypeError):
            nat_series_dtype_timestamp / 1.0
        with pytest.raises(TypeError):
            nat_series_dtype_timestamp / 1


class TestSeriesOperators(TestData):
    def test_op_method(self):
        def check(series, other, check_reverse=False):
            simple_ops = ['add', 'sub', 'mul', 'floordiv', 'truediv', 'pow']
            if not compat.PY3:
                simple_ops.append('div')

            for opname in simple_ops:
                op = getattr(Series, opname)

                if op == 'div':
                    alt = operator.truediv
                else:
                    alt = getattr(operator, opname)

                result = op(series, other)
                expected = alt(series, other)
                assert_almost_equal(result, expected)
                if check_reverse:
                    rop = getattr(Series, "r" + opname)
                    result = rop(series, other)
                    expected = alt(other, series)
                    assert_almost_equal(result, expected)

        check(self.ts, self.ts * 2)
        check(self.ts, self.ts[::2])
        check(self.ts, 5, check_reverse=True)
        check(tm.makeFloatSeries(), tm.makeFloatSeries(), check_reverse=True)

    def test_neg(self):
        assert_series_equal(-self.series, -1 * self.series)

    def test_invert(self):
        assert_series_equal(-(self.series < 0), ~(self.series < 0))

    def test_operators(self):
        def _check_op(series, other, op, pos_only=False,
                      check_dtype=True):
            left = np.abs(series) if pos_only else series
            right = np.abs(other) if pos_only else other

            cython_or_numpy = op(left, right)
            python = left.combine(right, op)
            assert_series_equal(cython_or_numpy, python,
                                check_dtype=check_dtype)

        def check(series, other):
            simple_ops = ['add', 'sub', 'mul', 'truediv', 'floordiv', 'mod']

            for opname in simple_ops:
                _check_op(series, other, getattr(operator, opname))

            _check_op(series, other, operator.pow, pos_only=True)

            _check_op(series, other, lambda x, y: operator.add(y, x))
            _check_op(series, other, lambda x, y: operator.sub(y, x))
            _check_op(series, other, lambda x, y: operator.truediv(y, x))
            _check_op(series, other, lambda x, y: operator.floordiv(y, x))
            _check_op(series, other, lambda x, y: operator.mul(y, x))
            _check_op(series, other, lambda x, y: operator.pow(y, x),
                      pos_only=True)
            _check_op(series, other, lambda x, y: operator.mod(y, x))

        check(self.ts, self.ts * 2)
        check(self.ts, self.ts * 0)
        check(self.ts, self.ts[::2])
        check(self.ts, 5)

        def check_comparators(series, other, check_dtype=True):
            _check_op(series, other, operator.gt, check_dtype=check_dtype)
            _check_op(series, other, operator.ge, check_dtype=check_dtype)
            _check_op(series, other, operator.eq, check_dtype=check_dtype)
            _check_op(series, other, operator.lt, check_dtype=check_dtype)
            _check_op(series, other, operator.le, check_dtype=check_dtype)

        check_comparators(self.ts, 5)
        check_comparators(self.ts, self.ts + 1, check_dtype=False)

    def test_divmod(self):
        def check(series, other):
            results = divmod(series, other)
            if isinstance(other, Iterable) and len(series) != len(other):
                # if the lengths don't match, this is the test where we use
                # `self.ts[::2]`. Pad every other value in `other_np` with nan.
                other_np = []
                for n in other:
                    other_np.append(n)
                    other_np.append(np.nan)
            else:
                other_np = other
            other_np = np.asarray(other_np)
            with np.errstate(all='ignore'):
                expecteds = divmod(series.values, np.asarray(other_np))

            for result, expected in zip(results, expecteds):
                # check the values, name, and index separatly
                assert_almost_equal(np.asarray(result), expected)

                assert result.name == series.name
                assert_index_equal(result.index, series.index)

        check(self.ts, self.ts * 2)
        check(self.ts, self.ts * 0)
        check(self.ts, self.ts[::2])
        check(self.ts, 5)

    def test_operators_empty_int_corner(self):
        s1 = Series([], [], dtype=np.int32)
        s2 = Series({'x': 0.})
        assert_series_equal(s1 * s2, Series([np.nan], index=['x']))

    def test_invalid_ops(self):
        # invalid ops
        pytest.raises(Exception, self.objSeries.__add__, 1)
        pytest.raises(Exception, self.objSeries.__add__,
                      np.array(1, dtype=np.int64))
        pytest.raises(Exception, self.objSeries.__sub__, 1)
        pytest.raises(Exception, self.objSeries.__sub__,
                      np.array(1, dtype=np.int64))

    def test_timedelta64_conversions(self):
        startdate = Series(date_range('2013-01-01', '2013-01-03'))
        enddate = Series(date_range('2013-03-01', '2013-03-03'))

        s1 = enddate - startdate
        s1[2] = np.nan

        for m in [1, 3, 10]:
            for unit in ['D', 'h', 'm', 's', 'ms', 'us', 'ns']:

                # op
                expected = s1.apply(lambda x: x / np.timedelta64(m, unit))
                result = s1 / np.timedelta64(m, unit)
                assert_series_equal(result, expected)

                if m == 1 and unit != 'ns':

                    # astype
                    result = s1.astype("timedelta64[{0}]".format(unit))
                    assert_series_equal(result, expected)

                # reverse op
                expected = s1.apply(
                    lambda x: Timedelta(np.timedelta64(m, unit)) / x)
                result = np.timedelta64(m, unit) / s1

        # astype
        s = Series(date_range('20130101', periods=3))
        result = s.astype(object)
        assert isinstance(result.iloc[0], datetime)
        assert result.dtype == np.object_

        result = s1.astype(object)
        assert isinstance(result.iloc[0], timedelta)
        assert result.dtype == np.object_

    @pytest.mark.parametrize('op', [operator.add, operator.sub])
    def test_timedelta64_equal_timedelta_supported_ops(self, op):
        ser = Series([Timestamp('20130301'), Timestamp('20130228 23:00:00'),
                      Timestamp('20130228 22:00:00'),
                      Timestamp('20130228 21:00:00')])

        intervals = 'D', 'h', 'm', 's', 'us'

        # TODO: unused
        # npy16_mappings = {'D': 24 * 60 * 60 * 1000000,
        #                   'h': 60 * 60 * 1000000,
        #                   'm': 60 * 1000000,
        #                   's': 1000000,
        #                   'us': 1}

        def timedelta64(*args):
            return sum(starmap(np.timedelta64, zip(args, intervals)))

        for d, h, m, s, us in product(*([range(2)] * 5)):
            nptd = timedelta64(d, h, m, s, us)
            pytd = timedelta(days=d, hours=h, minutes=m, seconds=s,
                             microseconds=us)
            lhs = op(ser, nptd)
            rhs = op(ser, pytd)

            try:
                assert_series_equal(lhs, rhs)
            except:
                raise AssertionError(
                    "invalid comparsion [op->{0},d->{1},h->{2},m->{3},"
                    "s->{4},us->{5}]\n{6}\n{7}\n".format(op, d, h, m, s,
                                                         us, lhs, rhs))

    def test_ops_nat_mixed_datetime64_timedelta64(self):
        # GH 11349
        timedelta_series = Series([NaT, Timedelta('1s')])
        datetime_series = Series([NaT, Timestamp('19900315')])
        nat_series_dtype_timedelta = Series([NaT, NaT],
                                            dtype='timedelta64[ns]')
        nat_series_dtype_timestamp = Series([NaT, NaT], dtype='datetime64[ns]')
        single_nat_dtype_datetime = Series([NaT], dtype='datetime64[ns]')
        single_nat_dtype_timedelta = Series([NaT], dtype='timedelta64[ns]')

        # subtraction
        assert_series_equal(datetime_series - single_nat_dtype_datetime,
                            nat_series_dtype_timedelta)

        assert_series_equal(datetime_series - single_nat_dtype_timedelta,
                            nat_series_dtype_timestamp)
        assert_series_equal(-single_nat_dtype_timedelta + datetime_series,
                            nat_series_dtype_timestamp)

        # without a Series wrapping the NaT, it is ambiguous
        # whether it is a datetime64 or timedelta64
        # defaults to interpreting it as timedelta64
        assert_series_equal(nat_series_dtype_timestamp -
                            single_nat_dtype_datetime,
                            nat_series_dtype_timedelta)

        assert_series_equal(nat_series_dtype_timestamp -
                            single_nat_dtype_timedelta,
                            nat_series_dtype_timestamp)
        assert_series_equal(-single_nat_dtype_timedelta +
                            nat_series_dtype_timestamp,
                            nat_series_dtype_timestamp)

        with pytest.raises(TypeError):
            timedelta_series - single_nat_dtype_datetime

        # addition
        assert_series_equal(nat_series_dtype_timestamp +
                            single_nat_dtype_timedelta,
                            nat_series_dtype_timestamp)
        assert_series_equal(single_nat_dtype_timedelta +
                            nat_series_dtype_timestamp,
                            nat_series_dtype_timestamp)

        assert_series_equal(nat_series_dtype_timestamp +
                            single_nat_dtype_timedelta,
                            nat_series_dtype_timestamp)
        assert_series_equal(single_nat_dtype_timedelta +
                            nat_series_dtype_timestamp,
                            nat_series_dtype_timestamp)

        assert_series_equal(nat_series_dtype_timedelta +
                            single_nat_dtype_datetime,
                            nat_series_dtype_timestamp)
        assert_series_equal(single_nat_dtype_datetime +
                            nat_series_dtype_timedelta,
                            nat_series_dtype_timestamp)

    def test_ops_datetimelike_align(self):
        # GH 7500
        # datetimelike ops need to align
        dt = Series(date_range('2012-1-1', periods=3, freq='D'))
        dt.iloc[2] = np.nan
        dt2 = dt[::-1]

        expected = Series([timedelta(0), timedelta(0), pd.NaT])
        # name is reset
        result = dt2 - dt
        assert_series_equal(result, expected)

        expected = Series(expected, name=0)
        result = (dt2.to_frame() - dt.to_frame())[0]
        assert_series_equal(result, expected)

    def test_return_dtypes_bool_op_costant(self):
        # gh15115
        s = pd.Series([1, 3, 2], index=range(3))
        const = 2
        for op in ['eq', 'ne', 'gt', 'lt', 'ge', 'le']:
            result = getattr(s, op)(const).get_dtype_counts()
            tm.assert_series_equal(result, Series([1], ['bool']))

        # empty Series
        empty = s.iloc[:0]
        for op in ['eq', 'ne', 'gt', 'lt', 'ge', 'le']:
            result = getattr(empty, op)(const).get_dtype_counts()
            tm.assert_series_equal(result, Series([1], ['bool']))

    def test_operators_bitwise(self):
        # GH 9016: support bitwise op for integer types
        index = list('bca')

        s_tft = Series([True, False, True], index=index)
        s_fff = Series([False, False, False], index=index)
        s_tff = Series([True, False, False], index=index)
        s_empty = Series([])

        # TODO: unused
        # s_0101 = Series([0, 1, 0, 1])

        s_0123 = Series(range(4), dtype='int64')
        s_3333 = Series([3] * 4)
        s_4444 = Series([4] * 4)

        res = s_tft & s_empty
        expected = s_fff
        assert_series_equal(res, expected)

        res = s_tft | s_empty
        expected = s_tft
        assert_series_equal(res, expected)

        res = s_0123 & s_3333
        expected = Series(range(4), dtype='int64')
        assert_series_equal(res, expected)

        res = s_0123 | s_4444
        expected = Series(range(4, 8), dtype='int64')
        assert_series_equal(res, expected)

        s_a0b1c0 = Series([1], list('b'))

        res = s_tft & s_a0b1c0
        expected = s_tff.reindex(list('abc'))
        assert_series_equal(res, expected)

        res = s_tft | s_a0b1c0
        expected = s_tft.reindex(list('abc'))
        assert_series_equal(res, expected)

        n0 = 0
        res = s_tft & n0
        expected = s_fff
        assert_series_equal(res, expected)

        res = s_0123 & n0
        expected = Series([0] * 4)
        assert_series_equal(res, expected)

        n1 = 1
        res = s_tft & n1
        expected = s_tft
        assert_series_equal(res, expected)

        res = s_0123 & n1
        expected = Series([0, 1, 0, 1])
        assert_series_equal(res, expected)

        s_1111 = Series([1] * 4, dtype='int8')
        res = s_0123 & s_1111
        expected = Series([0, 1, 0, 1], dtype='int64')
        assert_series_equal(res, expected)

        res = s_0123.astype(np.int16) | s_1111.astype(np.int32)
        expected = Series([1, 1, 3, 3], dtype='int32')
        assert_series_equal(res, expected)

        pytest.raises(TypeError, lambda: s_1111 & 'a')
        pytest.raises(TypeError, lambda: s_1111 & ['a', 'b', 'c', 'd'])
        pytest.raises(TypeError, lambda: s_0123 & np.NaN)
        pytest.raises(TypeError, lambda: s_0123 & 3.14)
        pytest.raises(TypeError, lambda: s_0123 & [0.1, 4, 3.14, 2])

        # s_0123 will be all false now because of reindexing like s_tft
        if compat.PY3:
            # unable to sort incompatible object via .union.
            exp = Series([False] * 7, index=['b', 'c', 'a', 0, 1, 2, 3])
            with tm.assert_produces_warning(RuntimeWarning):
                assert_series_equal(s_tft & s_0123, exp)
        else:
            exp = Series([False] * 7, index=[0, 1, 2, 3, 'a', 'b', 'c'])
            assert_series_equal(s_tft & s_0123, exp)

        # s_tft will be all false now because of reindexing like s_0123
        if compat.PY3:
            # unable to sort incompatible object via .union.
            exp = Series([False] * 7, index=[0, 1, 2, 3, 'b', 'c', 'a'])
            with tm.assert_produces_warning(RuntimeWarning):
                assert_series_equal(s_0123 & s_tft, exp)
        else:
            exp = Series([False] * 7, index=[0, 1, 2, 3, 'a', 'b', 'c'])
            assert_series_equal(s_0123 & s_tft, exp)

        assert_series_equal(s_0123 & False, Series([False] * 4))
        assert_series_equal(s_0123 ^ False, Series([False, True, True, True]))
        assert_series_equal(s_0123 & [False], Series([False] * 4))
        assert_series_equal(s_0123 & (False), Series([False] * 4))
        assert_series_equal(s_0123 & Series([False, np.NaN, False, False]),
                            Series([False] * 4))

        s_ftft = Series([False, True, False, True])
        assert_series_equal(s_0123 & Series([0.1, 4, -3.14, 2]), s_ftft)

        s_abNd = Series(['a', 'b', np.NaN, 'd'])
        res = s_0123 & s_abNd
        expected = s_ftft
        assert_series_equal(res, expected)

    def test_scalar_na_cmp_corners(self):
        s = Series([2, 3, 4, 5, 6, 7, 8, 9, 10])

        def tester(a, b):
            return a & b

        pytest.raises(TypeError, tester, s, datetime(2005, 1, 1))

        s = Series([2, 3, 4, 5, 6, 7, 8, 9, datetime(2005, 1, 1)])
        s[::2] = np.nan

        expected = Series(True, index=s.index)
        expected[::2] = False
        assert_series_equal(tester(s, list(s)), expected)

        d = DataFrame({'A': s})
        # TODO: Fix this exception - needs to be fixed! (see GH5035)
        # (previously this was a TypeError because series returned
        # NotImplemented

        # this is an alignment issue; these are equivalent
        # https://github.com/pandas-dev/pandas/issues/5284

        pytest.raises(ValueError, lambda: d.__and__(s, axis='columns'))
        pytest.raises(ValueError, tester, s, d)

        # this is wrong as its not a boolean result
        # result = d.__and__(s,axis='index')

    def test_operators_corner(self):
        series = self.ts

        empty = Series([], index=Index([]))

        result = series + empty
        assert np.isnan(result).all()

        result = empty + Series([], index=Index([]))
        assert len(result) == 0

        # TODO: this returned NotImplemented earlier, what to do?
        # deltas = Series([timedelta(1)] * 5, index=np.arange(5))
        # sub_deltas = deltas[::2]
        # deltas5 = deltas * 5
        # deltas = deltas + sub_deltas

        # float + int
        int_ts = self.ts.astype(int)[:-5]
        added = self.ts + int_ts
        expected = Series(self.ts.values[:-5] + int_ts.values,
                          index=self.ts.index[:-5], name='ts')
        tm.assert_series_equal(added[:-5], expected)

    def test_operators_reverse_object(self):
        # GH 56
        arr = Series(np.random.randn(10), index=np.arange(10), dtype=object)

        def _check_op(arr, op):
            result = op(1., arr)
            expected = op(1., arr.astype(float))
            assert_series_equal(result.astype(float), expected)

        _check_op(arr, operator.add)
        _check_op(arr, operator.sub)
        _check_op(arr, operator.mul)
        _check_op(arr, operator.truediv)
        _check_op(arr, operator.floordiv)

    def test_arith_ops_df_compat(self):
        # GH 1134
        s1 = pd.Series([1, 2, 3], index=list('ABC'), name='x')
        s2 = pd.Series([2, 2, 2], index=list('ABD'), name='x')

        exp = pd.Series([3.0, 4.0, np.nan, np.nan],
                        index=list('ABCD'), name='x')
        assert_series_equal(s1 + s2, exp)
        assert_series_equal(s2 + s1, exp)

        exp = pd.DataFrame({'x': [3.0, 4.0, np.nan, np.nan]},
                           index=list('ABCD'))
        assert_frame_equal(s1.to_frame() + s2.to_frame(), exp)
        assert_frame_equal(s2.to_frame() + s1.to_frame(), exp)

        # different length
        s3 = pd.Series([1, 2, 3], index=list('ABC'), name='x')
        s4 = pd.Series([2, 2, 2, 2], index=list('ABCD'), name='x')

        exp = pd.Series([3, 4, 5, np.nan],
                        index=list('ABCD'), name='x')
        assert_series_equal(s3 + s4, exp)
        assert_series_equal(s4 + s3, exp)

        exp = pd.DataFrame({'x': [3, 4, 5, np.nan]},
                           index=list('ABCD'))
        assert_frame_equal(s3.to_frame() + s4.to_frame(), exp)
        assert_frame_equal(s4.to_frame() + s3.to_frame(), exp)

    def test_bool_ops_df_compat(self):
        # GH 1134
        s1 = pd.Series([True, False, True], index=list('ABC'), name='x')
        s2 = pd.Series([True, True, False], index=list('ABD'), name='x')

        exp = pd.Series([True, False, False, False],
                        index=list('ABCD'), name='x')
        assert_series_equal(s1 & s2, exp)
        assert_series_equal(s2 & s1, exp)

        # True | np.nan => True
        exp = pd.Series([True, True, True, False],
                        index=list('ABCD'), name='x')
        assert_series_equal(s1 | s2, exp)
        # np.nan | True => np.nan, filled with False
        exp = pd.Series([True, True, False, False],
                        index=list('ABCD'), name='x')
        assert_series_equal(s2 | s1, exp)

        # DataFrame doesn't fill nan with False
        exp = pd.DataFrame({'x': [True, False, np.nan, np.nan]},
                           index=list('ABCD'))
        assert_frame_equal(s1.to_frame() & s2.to_frame(), exp)
        assert_frame_equal(s2.to_frame() & s1.to_frame(), exp)

        exp = pd.DataFrame({'x': [True, True, np.nan, np.nan]},
                           index=list('ABCD'))
        assert_frame_equal(s1.to_frame() | s2.to_frame(), exp)
        assert_frame_equal(s2.to_frame() | s1.to_frame(), exp)

        # different length
        s3 = pd.Series([True, False, True], index=list('ABC'), name='x')
        s4 = pd.Series([True, True, True, True], index=list('ABCD'), name='x')

        exp = pd.Series([True, False, True, False],
                        index=list('ABCD'), name='x')
        assert_series_equal(s3 & s4, exp)
        assert_series_equal(s4 & s3, exp)

        # np.nan | True => np.nan, filled with False
        exp = pd.Series([True, True, True, False],
                        index=list('ABCD'), name='x')
        assert_series_equal(s3 | s4, exp)
        # True | np.nan => True
        exp = pd.Series([True, True, True, True],
                        index=list('ABCD'), name='x')
        assert_series_equal(s4 | s3, exp)

        exp = pd.DataFrame({'x': [True, False, True, np.nan]},
                           index=list('ABCD'))
        assert_frame_equal(s3.to_frame() & s4.to_frame(), exp)
        assert_frame_equal(s4.to_frame() & s3.to_frame(), exp)

        exp = pd.DataFrame({'x': [True, True, True, np.nan]},
                           index=list('ABCD'))
        assert_frame_equal(s3.to_frame() | s4.to_frame(), exp)
        assert_frame_equal(s4.to_frame() | s3.to_frame(), exp)

    def test_series_frame_radd_bug(self):
        # GH 353
        vals = Series(tm.rands_array(5, 10))
        result = 'foo_' + vals
        expected = vals.map(lambda x: 'foo_' + x)
        assert_series_equal(result, expected)

        frame = DataFrame({'vals': vals})
        result = 'foo_' + frame
        expected = DataFrame({'vals': vals.map(lambda x: 'foo_' + x)})
        assert_frame_equal(result, expected)

        # really raise this time
        with pytest.raises(TypeError):
            datetime.now() + self.ts

        with pytest.raises(TypeError):
            self.ts + datetime.now()

    def test_series_radd_more(self):
        data = [[1, 2, 3],
                [1.1, 2.2, 3.3],
                [pd.Timestamp('2011-01-01'), pd.Timestamp('2011-01-02'),
                 pd.NaT],
                ['x', 'y', 1]]

        for d in data:
            for dtype in [None, object]:
                s = Series(d, dtype=dtype)
                with pytest.raises(TypeError):
                    'foo_' + s

        for dtype in [None, object]:
            res = 1 + pd.Series([1, 2, 3], dtype=dtype)
            exp = pd.Series([2, 3, 4], dtype=dtype)
            assert_series_equal(res, exp)
            res = pd.Series([1, 2, 3], dtype=dtype) + 1
            assert_series_equal(res, exp)

            res = np.nan + pd.Series([1, 2, 3], dtype=dtype)
            exp = pd.Series([np.nan, np.nan, np.nan], dtype=dtype)
            assert_series_equal(res, exp)
            res = pd.Series([1, 2, 3], dtype=dtype) + np.nan
            assert_series_equal(res, exp)

            s = pd.Series([pd.Timedelta('1 days'), pd.Timedelta('2 days'),
                           pd.Timedelta('3 days')], dtype=dtype)
            exp = pd.Series([pd.Timedelta('4 days'), pd.Timedelta('5 days'),
                             pd.Timedelta('6 days')])
            assert_series_equal(pd.Timedelta('3 days') + s, exp)
            assert_series_equal(s + pd.Timedelta('3 days'), exp)

        s = pd.Series(['x', np.nan, 'x'])
        assert_series_equal('a' + s, pd.Series(['ax', np.nan, 'ax']))
        assert_series_equal(s + 'a', pd.Series(['xa', np.nan, 'xa']))

    def test_frame_radd_more(self):
        data = [[1, 2, 3],
                [1.1, 2.2, 3.3],
                [pd.Timestamp('2011-01-01'), pd.Timestamp('2011-01-02'),
                 pd.NaT],
                ['x', 'y', 1]]

        for d in data:
            for dtype in [None, object]:
                s = DataFrame(d, dtype=dtype)
                with pytest.raises(TypeError):
                    'foo_' + s

        for dtype in [None, object]:
            res = 1 + pd.DataFrame([1, 2, 3], dtype=dtype)
            exp = pd.DataFrame([2, 3, 4], dtype=dtype)
            assert_frame_equal(res, exp)
            res = pd.DataFrame([1, 2, 3], dtype=dtype) + 1
            assert_frame_equal(res, exp)

            res = np.nan + pd.DataFrame([1, 2, 3], dtype=dtype)
            exp = pd.DataFrame([np.nan, np.nan, np.nan], dtype=dtype)
            assert_frame_equal(res, exp)
            res = pd.DataFrame([1, 2, 3], dtype=dtype) + np.nan
            assert_frame_equal(res, exp)

        df = pd.DataFrame(['x', np.nan, 'x'])
        assert_frame_equal('a' + df, pd.DataFrame(['ax', np.nan, 'ax']))
        assert_frame_equal(df + 'a', pd.DataFrame(['xa', np.nan, 'xa']))

    def test_operators_frame(self):
        # rpow does not work with DataFrame
        df = DataFrame({'A': self.ts})

        assert_series_equal(self.ts + self.ts, self.ts + df['A'],
                            check_names=False)
        assert_series_equal(self.ts ** self.ts, self.ts ** df['A'],
                            check_names=False)
        assert_series_equal(self.ts < self.ts, self.ts < df['A'],
                            check_names=False)
        assert_series_equal(self.ts / self.ts, self.ts / df['A'],
                            check_names=False)

    def test_operators_combine(self):
        def _check_fill(meth, op, a, b, fill_value=0):
            exp_index = a.index.union(b.index)
            a = a.reindex(exp_index)
            b = b.reindex(exp_index)

            amask = isna(a)
            bmask = isna(b)

            exp_values = []
            for i in range(len(exp_index)):
                with np.errstate(all='ignore'):
                    if amask[i]:
                        if bmask[i]:
                            exp_values.append(nan)
                            continue
                        exp_values.append(op(fill_value, b[i]))
                    elif bmask[i]:
                        if amask[i]:
                            exp_values.append(nan)
                            continue
                        exp_values.append(op(a[i], fill_value))
                    else:
                        exp_values.append(op(a[i], b[i]))

            result = meth(a, b, fill_value=fill_value)
            expected = Series(exp_values, exp_index)
            assert_series_equal(result, expected)

        a = Series([nan, 1., 2., 3., nan], index=np.arange(5))
        b = Series([nan, 1, nan, 3, nan, 4.], index=np.arange(6))

        pairings = []
        for op in ['add', 'sub', 'mul', 'pow', 'truediv', 'floordiv']:
            fv = 0
            lop = getattr(Series, op)
            lequiv = getattr(operator, op)
            rop = getattr(Series, 'r' + op)
            # bind op at definition time...
            requiv = lambda x, y, op=op: getattr(operator, op)(y, x)
            pairings.append((lop, lequiv, fv))
            pairings.append((rop, requiv, fv))

        if compat.PY3:
            pairings.append((Series.div, operator.truediv, 1))
            pairings.append((Series.rdiv, lambda x, y: operator.truediv(y, x),
                             1))
        else:
            pairings.append((Series.div, operator.div, 1))
            pairings.append((Series.rdiv, lambda x, y: operator.div(y, x), 1))

        for op, equiv_op, fv in pairings:
            result = op(a, b)
            exp = equiv_op(a, b)
            assert_series_equal(result, exp)
            _check_fill(op, equiv_op, a, b, fill_value=fv)
            # should accept axis=0 or axis='rows'
            op(a, b, axis=0)

    def test_operators_na_handling(self):
        from decimal import Decimal
        from datetime import date
        s = Series([Decimal('1.3'), Decimal('2.3')],
                   index=[date(2012, 1, 1), date(2012, 1, 2)])

        result = s + s.shift(1)
        result2 = s.shift(1) + s
        assert isna(result[0])
        assert isna(result2[0])

        s = Series(['foo', 'bar', 'baz', np.nan])
        result = 'prefix_' + s
        expected = Series(['prefix_foo', 'prefix_bar', 'prefix_baz', np.nan])
        assert_series_equal(result, expected)

        result = s + '_suffix'
        expected = Series(['foo_suffix', 'bar_suffix', 'baz_suffix', np.nan])
        assert_series_equal(result, expected)

    def test_datetime64_with_index(self):

        # arithmetic integer ops with an index
        s = Series(np.random.randn(5))
        expected = s - s.index.to_series()
        result = s - s.index
        assert_series_equal(result, expected)

        # GH 4629
        # arithmetic datetime64 ops with an index
        s = Series(date_range('20130101', periods=5),
                   index=date_range('20130101', periods=5))
        expected = s - s.index.to_series()
        result = s - s.index
        assert_series_equal(result, expected)

        result = s - s.index.to_period()
        assert_series_equal(result, expected)

        df = DataFrame(np.random.randn(5, 2),
                       index=date_range('20130101', periods=5))
        df['date'] = Timestamp('20130102')
        df['expected'] = df['date'] - df.index.to_series()
        df['result'] = df['date'] - df.index
        assert_series_equal(df['result'], df['expected'], check_names=False)

    def test_dti_tz_convert_to_utc(self):
        base = pd.DatetimeIndex(['2011-01-01', '2011-01-02', '2011-01-03'],
                                tz='UTC')
        idx1 = base.tz_convert('Asia/Tokyo')[:2]
        idx2 = base.tz_convert('US/Eastern')[1:]

        res = Series([1, 2], index=idx1) + Series([1, 1], index=idx2)
        assert_series_equal(res, Series([np.nan, 3, np.nan], index=base))

    def test_op_duplicate_index(self):
        # GH14227
        s1 = Series([1, 2], index=[1, 1])
        s2 = Series([10, 10], index=[1, 2])
        result = s1 + s2
        expected = pd.Series([11, 12, np.nan], index=[1, 1, 2])
        assert_series_equal(result, expected)

    @pytest.mark.parametrize(
        "test_input,error_type",
        [
            (pd.Series([]), ValueError),

            # For strings, or any Series with dtype 'O'
            (pd.Series(['foo', 'bar', 'baz']), TypeError),
            (pd.Series([(1,), (2,)]), TypeError),

            # For mixed data types
            (
                pd.Series(['foo', 'foo', 'bar', 'bar', None, np.nan, 'baz']),
                TypeError
            ),
        ]
    )
    def test_assert_idxminmax_raises(self, test_input, error_type):
        """
        Cases where ``Series.argmax`` and related should raise an exception
        """
        with pytest.raises(error_type):
            test_input.idxmin()
        with pytest.raises(error_type):
            test_input.idxmin(skipna=False)
        with pytest.raises(error_type):
            test_input.idxmax()
        with pytest.raises(error_type):
            test_input.idxmax(skipna=False)

    def test_idxminmax_with_inf(self):
        # For numeric data with NA and Inf (GH #13595)
        s = pd.Series([0, -np.inf, np.inf, np.nan])

        assert s.idxmin() == 1
        assert np.isnan(s.idxmin(skipna=False))

        assert s.idxmax() == 2
        assert np.isnan(s.idxmax(skipna=False))

        # Using old-style behavior that treats floating point nan, -inf, and
        # +inf as missing
        with pd.option_context('mode.use_inf_as_na', True):
            assert s.idxmin() == 0
            assert np.isnan(s.idxmin(skipna=False))
            assert s.idxmax() == 0
            np.isnan(s.idxmax(skipna=False))