test_datetime_index.py

# pylint: disable=E1101

from datetime import datetime, timedelta
from functools import partial
from warnings import catch_warnings, simplefilter

import numpy as np
import pytest
import pytz

from pandas.compat import range
from pandas.errors import UnsupportedFunctionCall

import pandas as pd
from pandas import (
    DataFrame, Index, Panel, Series, Timedelta, Timestamp, isna, notna)
from pandas.core.indexes.datetimes import date_range
from pandas.core.indexes.period import Period, period_range
from pandas.core.indexes.timedeltas import timedelta_range
from pandas.core.resample import DatetimeIndex, TimeGrouper
from pandas.tests.resample.test_base import Base
import pandas.util.testing as tm
from pandas.util.testing import (
    assert_almost_equal, assert_frame_equal, assert_series_equal)

import pandas.tseries.offsets as offsets
from pandas.tseries.offsets import BDay, Minute


class TestDatetimeIndex(Base):
    _index_factory = lambda x: date_range

    @pytest.fixture
    def _series_name(self):
        return 'dti'

    def setup_method(self, method):
        dti = date_range(start=datetime(2005, 1, 1),
                         end=datetime(2005, 1, 10), freq='Min')

        self.series = Series(np.random.rand(len(dti)), dti)

    def create_series(self):
        i = date_range(datetime(2005, 1, 1),
                       datetime(2005, 1, 10), freq='D')

        return Series(np.arange(len(i)), index=i, name='dti')

    def test_custom_grouper(self):

        dti = date_range(freq='Min', start=datetime(2005, 1, 1),
                         end=datetime(2005, 1, 10))

        s = Series(np.array([1] * len(dti)), index=dti, dtype='int64')

        b = TimeGrouper(Minute(5))
        g = s.groupby(b)

        # check all cython functions work
        funcs = ['add', 'mean', 'prod', 'ohlc', 'min', 'max', 'var']
        for f in funcs:
            g._cython_agg_general(f)

        b = TimeGrouper(Minute(5), closed='right', label='right')
        g = s.groupby(b)
        # check all cython functions work
        funcs = ['add', 'mean', 'prod', 'ohlc', 'min', 'max', 'var']
        for f in funcs:
            g._cython_agg_general(f)

        assert g.ngroups == 2593
        assert notna(g.mean()).all()

        # construct expected val
        arr = [1] + [5] * 2592
        idx = dti[0:-1:5]
        idx = idx.append(dti[-1:])
        expect = Series(arr, index=idx)

        # GH2763 - return in put dtype if we can
        result = g.agg(np.sum)
        assert_series_equal(result, expect)

        df = DataFrame(np.random.rand(len(dti), 10),
                       index=dti, dtype='float64')
        r = df.groupby(b).agg(np.sum)

        assert len(r.columns) == 10
        assert len(r.index) == 2593

    def test_resample_basic(self):
        rng = date_range('1/1/2000 00:00:00', '1/1/2000 00:13:00', freq='min',
                         name='index')
        s = Series(np.random.randn(14), index=rng)

        result = s.resample('5min', closed='right', label='right').mean()

        exp_idx = date_range('1/1/2000', periods=4, freq='5min', name='index')
        expected = Series([s[0], s[1:6].mean(), s[6:11].mean(), s[11:].mean()],
                          index=exp_idx)
        assert_series_equal(result, expected)
        assert result.index.name == 'index'

        result = s.resample('5min', closed='left', label='right').mean()

        exp_idx = date_range('1/1/2000 00:05', periods=3, freq='5min',
                             name='index')
        expected = Series([s[:5].mean(), s[5:10].mean(),
                           s[10:].mean()], index=exp_idx)
        assert_series_equal(result, expected)

        s = self.series
        result = s.resample('5Min').last()
        grouper = TimeGrouper(Minute(5), closed='left', label='left')
        expect = s.groupby(grouper).agg(lambda x: x[-1])
        assert_series_equal(result, expect)

    def test_resample_string_kwargs(self):
        # Test for issue #19303
        rng = date_range('1/1/2000 00:00:00', '1/1/2000 00:13:00', freq='min',
                         name='index')
        s = Series(np.random.randn(14), index=rng)

        # Check that wrong keyword argument strings raise an error
        with pytest.raises(ValueError):
            s.resample('5min', label='righttt').mean()
        with pytest.raises(ValueError):
            s.resample('5min', closed='righttt').mean()
        with pytest.raises(ValueError):
            s.resample('5min', convention='starttt').mean()

    def test_resample_how(self, downsample_method):
        rng = date_range('1/1/2000 00:00:00', '1/1/2000 00:13:00', freq='min',
                         name='index')
        s = Series(np.random.randn(14), index=rng)
        grouplist = np.ones_like(s)
        grouplist[0] = 0
        grouplist[1:6] = 1
        grouplist[6:11] = 2
        grouplist[11:] = 3
        arg = downsample_method

        def _ohlc(group):
            if isna(group).all():
                return np.repeat(np.nan, 4)
            return [group[0], group.max(), group.min(), group[-1]]

        inds = date_range('1/1/2000', periods=4, freq='5min', name='index')

        if arg == 'ohlc':
            func = _ohlc
        else:
            func = arg
        try:
            result = getattr(s.resample(
                '5min', closed='right', label='right'), arg)()

            expected = s.groupby(grouplist).agg(func)
            assert result.index.name == 'index'
            if arg == 'ohlc':
                expected = DataFrame(expected.values.tolist())
                expected.columns = ['open', 'high', 'low', 'close']
                expected.index = Index(inds, name='index')
                assert_frame_equal(result, expected)
            else:
                expected.index = inds
                assert_series_equal(result, expected)
        except BaseException as exc:

            exc.args += ('how=%s' % arg,)
            raise

    def test_numpy_compat(self):
        # see gh-12811
        s = Series([1, 2, 3, 4, 5], index=date_range(
            '20130101', periods=5, freq='s'))
        r = s.resample('2s')

        msg = "numpy operations are not valid with resample"

        for func in ('min', 'max', 'sum', 'prod',
                     'mean', 'var', 'std'):
            with pytest.raises(UnsupportedFunctionCall, match=msg):
                getattr(r, func)(func, 1, 2, 3)
            with pytest.raises(UnsupportedFunctionCall, match=msg):
                getattr(r, func)(axis=1)

    def test_resample_how_callables(self):
        # GH#7929
        data = np.arange(5, dtype=np.int64)
        ind = date_range(start='2014-01-01', periods=len(data), freq='d')
        df = DataFrame({"A": data, "B": data}, index=ind)

        def fn(x, a=1):
            return str(type(x))

        class FnClass(object):

            def __call__(self, x):
                return str(type(x))

        df_standard = df.resample("M").apply(fn)
        df_lambda = df.resample("M").apply(lambda x: str(type(x)))
        df_partial = df.resample("M").apply(partial(fn))
        df_partial2 = df.resample("M").apply(partial(fn, a=2))
        df_class = df.resample("M").apply(FnClass())

        assert_frame_equal(df_standard, df_lambda)
        assert_frame_equal(df_standard, df_partial)
        assert_frame_equal(df_standard, df_partial2)
        assert_frame_equal(df_standard, df_class)

    def test_resample_with_timedeltas(self):

        expected = DataFrame({'A': np.arange(1480)})
        expected = expected.groupby(expected.index // 30).sum()
        expected.index = pd.timedelta_range('0 days', freq='30T', periods=50)

        df = DataFrame({'A': np.arange(1480)}, index=pd.to_timedelta(
            np.arange(1480), unit='T'))
        result = df.resample('30T').sum()

        assert_frame_equal(result, expected)

        s = df['A']
        result = s.resample('30T').sum()
        assert_series_equal(result, expected['A'])

    def test_resample_single_period_timedelta(self):

        s = Series(list(range(5)), index=pd.timedelta_range(
            '1 day', freq='s', periods=5))
        result = s.resample('2s').sum()
        expected = Series([1, 5, 4], index=pd.timedelta_range(
            '1 day', freq='2s', periods=3))
        assert_series_equal(result, expected)

    def test_resample_timedelta_idempotency(self):

        # GH 12072
        index = pd.timedelta_range('0', periods=9, freq='10L')
        series = Series(range(9), index=index)
        result = series.resample('10L').mean()
        expected = series
        assert_series_equal(result, expected)

    def test_resample_rounding(self):
        # GH 8371
        # odd results when rounding is needed

        data = """date,time,value
11-08-2014,00:00:01.093,1
11-08-2014,00:00:02.159,1
11-08-2014,00:00:02.667,1
11-08-2014,00:00:03.175,1
11-08-2014,00:00:07.058,1
11-08-2014,00:00:07.362,1
11-08-2014,00:00:08.324,1
11-08-2014,00:00:08.830,1
11-08-2014,00:00:08.982,1
11-08-2014,00:00:09.815,1
11-08-2014,00:00:10.540,1
11-08-2014,00:00:11.061,1
11-08-2014,00:00:11.617,1
11-08-2014,00:00:13.607,1
11-08-2014,00:00:14.535,1
11-08-2014,00:00:15.525,1
11-08-2014,00:00:17.960,1
11-08-2014,00:00:20.674,1
11-08-2014,00:00:21.191,1"""

        from pandas.compat import StringIO
        df = pd.read_csv(StringIO(data), parse_dates={'timestamp': [
            'date', 'time']}, index_col='timestamp')
        df.index.name = None
        result = df.resample('6s').sum()
        expected = DataFrame({'value': [
            4, 9, 4, 2
        ]}, index=date_range('2014-11-08', freq='6s', periods=4))
        assert_frame_equal(result, expected)

        result = df.resample('7s').sum()
        expected = DataFrame({'value': [
            4, 10, 4, 1
        ]}, index=date_range('2014-11-08', freq='7s', periods=4))
        assert_frame_equal(result, expected)

        result = df.resample('11s').sum()
        expected = DataFrame({'value': [
            11, 8
        ]}, index=date_range('2014-11-08', freq='11s', periods=2))
        assert_frame_equal(result, expected)

        result = df.resample('13s').sum()
        expected = DataFrame({'value': [
            13, 6
        ]}, index=date_range('2014-11-08', freq='13s', periods=2))
        assert_frame_equal(result, expected)

        result = df.resample('17s').sum()
        expected = DataFrame({'value': [
            16, 3
        ]}, index=date_range('2014-11-08', freq='17s', periods=2))
        assert_frame_equal(result, expected)

    def test_resample_basic_from_daily(self):
        # from daily
        dti = date_range(start=datetime(2005, 1, 1),
                         end=datetime(2005, 1, 10), freq='D', name='index')

        s = Series(np.random.rand(len(dti)), dti)

        # to weekly
        result = s.resample('w-sun').last()

        assert len(result) == 3
        assert (result.index.dayofweek == [6, 6, 6]).all()
        assert result.iloc[0] == s['1/2/2005']
        assert result.iloc[1] == s['1/9/2005']
        assert result.iloc[2] == s.iloc[-1]

        result = s.resample('W-MON').last()
        assert len(result) == 2
        assert (result.index.dayofweek == [0, 0]).all()
        assert result.iloc[0] == s['1/3/2005']
        assert result.iloc[1] == s['1/10/2005']

        result = s.resample('W-TUE').last()
        assert len(result) == 2
        assert (result.index.dayofweek == [1, 1]).all()
        assert result.iloc[0] == s['1/4/2005']
        assert result.iloc[1] == s['1/10/2005']

        result = s.resample('W-WED').last()
        assert len(result) == 2
        assert (result.index.dayofweek == [2, 2]).all()
        assert result.iloc[0] == s['1/5/2005']
        assert result.iloc[1] == s['1/10/2005']

        result = s.resample('W-THU').last()
        assert len(result) == 2
        assert (result.index.dayofweek == [3, 3]).all()
        assert result.iloc[0] == s['1/6/2005']
        assert result.iloc[1] == s['1/10/2005']

        result = s.resample('W-FRI').last()
        assert len(result) == 2
        assert (result.index.dayofweek == [4, 4]).all()
        assert result.iloc[0] == s['1/7/2005']
        assert result.iloc[1] == s['1/10/2005']

        # to biz day
        result = s.resample('B').last()
        assert len(result) == 7
        assert (result.index.dayofweek == [4, 0, 1, 2, 3, 4, 0]).all()

        assert result.iloc[0] == s['1/2/2005']
        assert result.iloc[1] == s['1/3/2005']
        assert result.iloc[5] == s['1/9/2005']
        assert result.index.name == 'index'

    def test_resample_upsampling_picked_but_not_correct(self):

        # Test for issue #3020
        dates = date_range('01-Jan-2014', '05-Jan-2014', freq='D')
        series = Series(1, index=dates)

        result = series.resample('D').mean()
        assert result.index[0] == dates[0]

        # GH 5955
        # incorrect deciding to upsample when the axis frequency matches the
        # resample frequency

        import datetime
        s = Series(np.arange(1., 6), index=[datetime.datetime(
            1975, 1, i, 12, 0) for i in range(1, 6)])
        expected = Series(np.arange(1., 6), index=date_range(
            '19750101', periods=5, freq='D'))

        result = s.resample('D').count()
        assert_series_equal(result, Series(1, index=expected.index))

        result1 = s.resample('D').sum()
        result2 = s.resample('D').mean()
        assert_series_equal(result1, expected)
        assert_series_equal(result2, expected)

    def test_resample_frame_basic(self):
        df = tm.makeTimeDataFrame()

        b = TimeGrouper('M')
        g = df.groupby(b)

        # check all cython functions work
        funcs = ['add', 'mean', 'prod', 'min', 'max', 'var']
        for f in funcs:
            g._cython_agg_general(f)

        result = df.resample('A').mean()
        assert_series_equal(result['A'], df['A'].resample('A').mean())

        result = df.resample('M').mean()
        assert_series_equal(result['A'], df['A'].resample('M').mean())

        df.resample('M', kind='period').mean()
        df.resample('W-WED', kind='period').mean()

    @pytest.mark.parametrize('loffset', [timedelta(minutes=1),
                                         '1min', Minute(1),
                                         np.timedelta64(1, 'm')])
    def test_resample_loffset(self, loffset):
        # GH 7687
        rng = date_range('1/1/2000 00:00:00', '1/1/2000 00:13:00', freq='min')
        s = Series(np.random.randn(14), index=rng)

        result = s.resample('5min', closed='right', label='right',
                            loffset=loffset).mean()
        idx = date_range('1/1/2000', periods=4, freq='5min')
        expected = Series([s[0], s[1:6].mean(), s[6:11].mean(), s[11:].mean()],
                          index=idx + timedelta(minutes=1))
        assert_series_equal(result, expected)
        assert result.index.freq == Minute(5)

        # from daily
        dti = date_range(start=datetime(2005, 1, 1),
                         end=datetime(2005, 1, 10), freq='D')
        ser = Series(np.random.rand(len(dti)), dti)

        # to weekly
        result = ser.resample('w-sun').last()
        business_day_offset = BDay()
        expected = ser.resample('w-sun', loffset=-business_day_offset).last()
        assert result.index[0] - business_day_offset == expected.index[0]

    def test_resample_loffset_upsample(self):
        # GH 20744
        rng = date_range('1/1/2000 00:00:00', '1/1/2000 00:13:00', freq='min')
        s = Series(np.random.randn(14), index=rng)

        result = s.resample('5min', closed='right', label='right',
                            loffset=timedelta(minutes=1)).ffill()
        idx = date_range('1/1/2000', periods=4, freq='5min')
        expected = Series([s[0], s[5], s[10], s[-1]],
                          index=idx + timedelta(minutes=1))

        assert_series_equal(result, expected)

    def test_resample_loffset_count(self):
        # GH 12725
        start_time = '1/1/2000 00:00:00'
        rng = date_range(start_time, periods=100, freq='S')
        ts = Series(np.random.randn(len(rng)), index=rng)

        result = ts.resample('10S', loffset='1s').count()

        expected_index = (
            date_range(start_time, periods=10, freq='10S') +
            timedelta(seconds=1)
        )
        expected = Series(10, index=expected_index)

        assert_series_equal(result, expected)

        # Same issue should apply to .size() since it goes through
        #   same code path
        result = ts.resample('10S', loffset='1s').size()

        assert_series_equal(result, expected)

    def test_resample_upsample(self):
        # from daily
        dti = date_range(start=datetime(2005, 1, 1),
                         end=datetime(2005, 1, 10), freq='D', name='index')

        s = Series(np.random.rand(len(dti)), dti)

        # to minutely, by padding
        result = s.resample('Min').pad()
        assert len(result) == 12961
        assert result[0] == s[0]
        assert result[-1] == s[-1]

        assert result.index.name == 'index'

    def test_resample_how_method(self):
        # GH9915
        s = Series([11, 22],
                   index=[Timestamp('2015-03-31 21:48:52.672000'),
                          Timestamp('2015-03-31 21:49:52.739000')])
        expected = Series([11, np.NaN, np.NaN, np.NaN, np.NaN, np.NaN, 22],
                          index=[Timestamp('2015-03-31 21:48:50'),
                                 Timestamp('2015-03-31 21:49:00'),
                                 Timestamp('2015-03-31 21:49:10'),
                                 Timestamp('2015-03-31 21:49:20'),
                                 Timestamp('2015-03-31 21:49:30'),
                                 Timestamp('2015-03-31 21:49:40'),
                                 Timestamp('2015-03-31 21:49:50')])
        assert_series_equal(s.resample("10S").mean(), expected)

    def test_resample_extra_index_point(self):
        # GH#9756
        index = date_range(start='20150101', end='20150331', freq='BM')
        expected = DataFrame({'A': Series([21, 41, 63], index=index)})

        index = date_range(start='20150101', end='20150331', freq='B')
        df = DataFrame(
            {'A': Series(range(len(index)), index=index)}, dtype='int64')
        result = df.resample('BM').last()
        assert_frame_equal(result, expected)

    def test_upsample_with_limit(self):
        rng = date_range('1/1/2000', periods=3, freq='5t')
        ts = Series(np.random.randn(len(rng)), rng)

        result = ts.resample('t').ffill(limit=2)
        expected = ts.reindex(result.index, method='ffill', limit=2)
        assert_series_equal(result, expected)

    def test_nearest_upsample_with_limit(self):
        rng = date_range('1/1/2000', periods=3, freq='5t')
        ts = Series(np.random.randn(len(rng)), rng)

        result = ts.resample('t').nearest(limit=2)
        expected = ts.reindex(result.index, method='nearest', limit=2)
        assert_series_equal(result, expected)

    def test_resample_ohlc(self):
        s = self.series

        grouper = TimeGrouper(Minute(5))
        expect = s.groupby(grouper).agg(lambda x: x[-1])
        result = s.resample('5Min').ohlc()

        assert len(result) == len(expect)
        assert len(result.columns) == 4

        xs = result.iloc[-2]
        assert xs['open'] == s[-6]
        assert xs['high'] == s[-6:-1].max()
        assert xs['low'] == s[-6:-1].min()
        assert xs['close'] == s[-2]

        xs = result.iloc[0]
        assert xs['open'] == s[0]
        assert xs['high'] == s[:5].max()
        assert xs['low'] == s[:5].min()
        assert xs['close'] == s[4]

    def test_resample_ohlc_result(self):

        # GH 12332
        index = pd.date_range('1-1-2000', '2-15-2000', freq='h')
        index = index.union(pd.date_range('4-15-2000', '5-15-2000', freq='h'))
        s = Series(range(len(index)), index=index)

        a = s.loc[:'4-15-2000'].resample('30T').ohlc()
        assert isinstance(a, DataFrame)

        b = s.loc[:'4-14-2000'].resample('30T').ohlc()
        assert isinstance(b, DataFrame)

        # GH12348
        # raising on odd period
        rng = date_range('2013-12-30', '2014-01-07')
        index = rng.drop([Timestamp('2014-01-01'),
                          Timestamp('2013-12-31'),
                          Timestamp('2014-01-04'),
                          Timestamp('2014-01-05')])
        df = DataFrame(data=np.arange(len(index)), index=index)
        result = df.resample('B').mean()
        expected = df.reindex(index=date_range(rng[0], rng[-1], freq='B'))
        assert_frame_equal(result, expected)

    def test_resample_ohlc_dataframe(self):
        df = (
            DataFrame({
                'PRICE': {
                    Timestamp('2011-01-06 10:59:05', tz=None): 24990,
                    Timestamp('2011-01-06 12:43:33', tz=None): 25499,
                    Timestamp('2011-01-06 12:54:09', tz=None): 25499},
                'VOLUME': {
                    Timestamp('2011-01-06 10:59:05', tz=None): 1500000000,
                    Timestamp('2011-01-06 12:43:33', tz=None): 5000000000,
                    Timestamp('2011-01-06 12:54:09', tz=None): 100000000}})
        ).reindex(['VOLUME', 'PRICE'], axis=1)
        res = df.resample('H').ohlc()
        exp = pd.concat([df['VOLUME'].resample('H').ohlc(),
                         df['PRICE'].resample('H').ohlc()],
                        axis=1,
                        keys=['VOLUME', 'PRICE'])
        assert_frame_equal(exp, res)

        df.columns = [['a', 'b'], ['c', 'd']]
        res = df.resample('H').ohlc()
        exp.columns = pd.MultiIndex.from_tuples([
            ('a', 'c', 'open'), ('a', 'c', 'high'), ('a', 'c', 'low'),
            ('a', 'c', 'close'), ('b', 'd', 'open'), ('b', 'd', 'high'),
            ('b', 'd', 'low'), ('b', 'd', 'close')])
        assert_frame_equal(exp, res)

        # dupe columns fail atm
        # df.columns = ['PRICE', 'PRICE']

    def test_resample_dup_index(self):

        # GH 4812
        # dup columns with resample raising
        df = DataFrame(np.random.randn(4, 12), index=[2000, 2000, 2000, 2000],
                       columns=[Period(year=2000, month=i + 1, freq='M')
                                for i in range(12)])
        df.iloc[3, :] = np.nan
        result = df.resample('Q', axis=1).mean()
        expected = df.groupby(lambda x: int((x.month - 1) / 3), axis=1).mean()
        expected.columns = [
            Period(year=2000, quarter=i + 1, freq='Q') for i in range(4)]
        assert_frame_equal(result, expected)

    def test_resample_reresample(self):
        dti = date_range(start=datetime(2005, 1, 1),
                         end=datetime(2005, 1, 10), freq='D')
        s = Series(np.random.rand(len(dti)), dti)
        bs = s.resample('B', closed='right', label='right').mean()
        result = bs.resample('8H').mean()
        assert len(result) == 22
        assert isinstance(result.index.freq, offsets.DateOffset)
        assert result.index.freq == offsets.Hour(8)

    def test_resample_timestamp_to_period(self, simple_date_range_series):
        ts = simple_date_range_series('1/1/1990', '1/1/2000')

        result = ts.resample('A-DEC', kind='period').mean()
        expected = ts.resample('A-DEC').mean()
        expected.index = period_range('1990', '2000', freq='a-dec')
        assert_series_equal(result, expected)

        result = ts.resample('A-JUN', kind='period').mean()
        expected = ts.resample('A-JUN').mean()
        expected.index = period_range('1990', '2000', freq='a-jun')
        assert_series_equal(result, expected)

        result = ts.resample('M', kind='period').mean()
        expected = ts.resample('M').mean()
        expected.index = period_range('1990-01', '2000-01', freq='M')
        assert_series_equal(result, expected)

        result = ts.resample('M', kind='period').mean()
        expected = ts.resample('M').mean()
        expected.index = period_range('1990-01', '2000-01', freq='M')
        assert_series_equal(result, expected)

    def test_ohlc_5min(self):
        def _ohlc(group):
            if isna(group).all():
                return np.repeat(np.nan, 4)
            return [group[0], group.max(), group.min(), group[-1]]

        rng = date_range('1/1/2000 00:00:00', '1/1/2000 5:59:50', freq='10s')
        ts = Series(np.random.randn(len(rng)), index=rng)

        resampled = ts.resample('5min', closed='right',
                                label='right').ohlc()

        assert (resampled.loc['1/1/2000 00:00'] == ts[0]).all()

        exp = _ohlc(ts[1:31])
        assert (resampled.loc['1/1/2000 00:05'] == exp).all()

        exp = _ohlc(ts['1/1/2000 5:55:01':])
        assert (resampled.loc['1/1/2000 6:00:00'] == exp).all()

    def test_downsample_non_unique(self):
        rng = date_range('1/1/2000', '2/29/2000')
        rng2 = rng.repeat(5).values
        ts = Series(np.random.randn(len(rng2)), index=rng2)

        result = ts.resample('M').mean()

        expected = ts.groupby(lambda x: x.month).mean()
        assert len(result) == 2
        assert_almost_equal(result[0], expected[1])
        assert_almost_equal(result[1], expected[2])

    def test_asfreq_non_unique(self):
        # GH #1077
        rng = date_range('1/1/2000', '2/29/2000')
        rng2 = rng.repeat(2).values
        ts = Series(np.random.randn(len(rng2)), index=rng2)

        pytest.raises(Exception, ts.asfreq, 'B')

    def test_resample_axis1(self):
        rng = date_range('1/1/2000', '2/29/2000')
        df = DataFrame(np.random.randn(3, len(rng)), columns=rng,
                       index=['a', 'b', 'c'])

        result = df.resample('M', axis=1).mean()
        expected = df.T.resample('M').mean().T
        tm.assert_frame_equal(result, expected)

    def test_resample_panel(self):
        rng = date_range('1/1/2000', '6/30/2000')
        n = len(rng)

        with catch_warnings(record=True):
            simplefilter("ignore", FutureWarning)
            panel = Panel(np.random.randn(3, n, 5),
                          items=['one', 'two', 'three'],
                          major_axis=rng,
                          minor_axis=['a', 'b', 'c', 'd', 'e'])

            result = panel.resample('M', axis=1).mean()

            def p_apply(panel, f):
                result = {}
                for item in panel.items:
                    result[item] = f(panel[item])
                return Panel(result, items=panel.items)

            expected = p_apply(panel, lambda x: x.resample('M').mean())
            tm.assert_panel_equal(result, expected)

            panel2 = panel.swapaxes(1, 2)
            result = panel2.resample('M', axis=2).mean()
            expected = p_apply(panel2,
                               lambda x: x.resample('M', axis=1).mean())
            tm.assert_panel_equal(result, expected)

    @pytest.mark.filterwarnings("ignore:\\nPanel:FutureWarning")
    def test_resample_panel_numpy(self):
        rng = date_range('1/1/2000', '6/30/2000')
        n = len(rng)

        with catch_warnings(record=True):
            panel = Panel(np.random.randn(3, n, 5),
                          items=['one', 'two', 'three'],
                          major_axis=rng,
                          minor_axis=['a', 'b', 'c', 'd', 'e'])

            result = panel.resample('M', axis=1).apply(lambda x: x.mean(1))
            expected = panel.resample('M', axis=1).mean()
            tm.assert_panel_equal(result, expected)

            panel = panel.swapaxes(1, 2)
            result = panel.resample('M', axis=2).apply(lambda x: x.mean(2))
            expected = panel.resample('M', axis=2).mean()
            tm.assert_panel_equal(result, expected)

    def test_resample_anchored_ticks(self):
        # If a fixed delta (5 minute, 4 hour) evenly divides a day, we should
        # "anchor" the origin at midnight so we get regular intervals rather
        # than starting from the first timestamp which might start in the
        # middle of a desired interval

        rng = date_range('1/1/2000 04:00:00', periods=86400, freq='s')
        ts = Series(np.random.randn(len(rng)), index=rng)
        ts[:2] = np.nan  # so results are the same

        freqs = ['t', '5t', '15t', '30t', '4h', '12h']
        for freq in freqs:
            result = ts[2:].resample(freq, closed='left', label='left').mean()
            expected = ts.resample(freq, closed='left', label='left').mean()
            assert_series_equal(result, expected)

    def test_resample_single_group(self):
        mysum = lambda x: x.sum()

        rng = date_range('2000-1-1', '2000-2-10', freq='D')
        ts = Series(np.random.randn(len(rng)), index=rng)
        assert_series_equal(ts.resample('M').sum(),
                            ts.resample('M').apply(mysum))

        rng = date_range('2000-1-1', '2000-1-10', freq='D')
        ts = Series(np.random.randn(len(rng)), index=rng)
        assert_series_equal(ts.resample('M').sum(),
                            ts.resample('M').apply(mysum))

        # GH 3849
        s = Series([30.1, 31.6], index=[Timestamp('20070915 15:30:00'),
                                        Timestamp('20070915 15:40:00')])
        expected = Series([0.75], index=[Timestamp('20070915')])
        result = s.resample('D').apply(lambda x: np.std(x))
        assert_series_equal(result, expected)

    def test_resample_base(self):
        rng = date_range('1/1/2000 00:00:00', '1/1/2000 02:00', freq='s')
        ts = Series(np.random.randn(len(rng)), index=rng)

        resampled = ts.resample('5min', base=2).mean()
        exp_rng = date_range('12/31/1999 23:57:00', '1/1/2000 01:57',
                             freq='5min')
        tm.assert_index_equal(resampled.index, exp_rng)

    def test_resample_base_with_timedeltaindex(self):

        # GH 10530
        rng = timedelta_range(start='0s', periods=25, freq='s')
        ts = Series(np.random.randn(len(rng)), index=rng)

        with_base = ts.resample('2s', base=5).mean()
        without_base = ts.resample('2s').mean()

        exp_without_base = timedelta_range(start='0s', end='25s', freq='2s')
        exp_with_base = timedelta_range(start='5s', end='29s', freq='2s')

        tm.assert_index_equal(without_base.index, exp_without_base)
        tm.assert_index_equal(with_base.index, exp_with_base)

    def test_resample_categorical_data_with_timedeltaindex(self):
        # GH #12169
        df = DataFrame({'Group_obj': 'A'},
                       index=pd.to_timedelta(list(range(20)), unit='s'))
        df['Group'] = df['Group_obj'].astype('category')
        result = df.resample('10s').agg(lambda x: (x.value_counts().index[0]))
        expected = DataFrame({'Group_obj': ['A', 'A'],
                              'Group': ['A', 'A']},
                             index=pd.to_timedelta([0, 10], unit='s'))
        expected = expected.reindex(['Group_obj', 'Group'], axis=1)
        expected['Group'] = expected['Group_obj'].astype('category')
        tm.assert_frame_equal(result, expected)

    def test_resample_daily_anchored(self):
        rng = date_range('1/1/2000 0:00:00', periods=10000, freq='T')
        ts = Series(np.random.randn(len(rng)), index=rng)
        ts[:2] = np.nan  # so results are the same

        result = ts[2:].resample('D', closed='left', label='left').mean()
        expected = ts.resample('D', closed='left', label='left').mean()
        assert_series_equal(result, expected)

    def test_resample_to_period_monthly_buglet(self):
        # GH #1259

        rng = date_range('1/1/2000', '12/31/2000')
        ts = Series(np.random.randn(len(rng)), index=rng)

        result = ts.resample('M', kind='period').mean()
        exp_index = period_range('Jan-2000', 'Dec-2000', freq='M')
        tm.assert_index_equal(result.index, exp_index)

    def test_period_with_agg(self):

        # aggregate a period resampler with a lambda
        s2 = Series(np.random.randint(0, 5, 50),
                    index=pd.period_range('2012-01-01', freq='H', periods=50),
                    dtype='float64')

        expected = s2.to_timestamp().resample('D').mean().to_period()
        result = s2.resample('D').agg(lambda x: x.mean())
        assert_series_equal(result, expected)

    def test_resample_segfault(self):
        # GH 8573
        # segfaulting in older versions
        all_wins_and_wagers = [
            (1, datetime(2013, 10, 1, 16, 20), 1, 0),
            (2, datetime(2013, 10, 1, 16, 10), 1, 0),
            (2, datetime(2013, 10, 1, 18, 15), 1, 0),
            (2, datetime(2013, 10, 1, 16, 10, 31), 1, 0)]

        df = DataFrame.from_records(all_wins_and_wagers,
                                    columns=("ID", "timestamp", "A", "B")
                                    ).set_index("timestamp")
        result = df.groupby("ID").resample("5min").sum()
        expected = df.groupby("ID").apply(lambda x: x.resample("5min").sum())
        assert_frame_equal(result, expected)

    def test_resample_dtype_preservation(self):

        # GH 12202
        # validation tests for dtype preservation

        df = DataFrame({'date': pd.date_range(start='2016-01-01',
                                              periods=4, freq='W'),
                        'group': [1, 1, 2, 2],
                        'val': Series([5, 6, 7, 8],
                                      dtype='int32')}
                       ).set_index('date')

        result = df.resample('1D').ffill()
        assert result.val.dtype == np.int32

        result = df.groupby('group').resample('1D').ffill()
        assert result.val.dtype == np.int32

    def test_resample_dtype_coerceion(self):

        pytest.importorskip('scipy.interpolate')

        # GH 16361
        df = {"a": [1, 3, 1, 4]}
        df = DataFrame(df, index=pd.date_range("2017-01-01", "2017-01-04"))

        expected = (df.astype("float64")
                    .resample("H")
                    .mean()
                    ["a"]
                    .interpolate("cubic")
                    )

        result = df.resample("H")["a"].mean().interpolate("cubic")
        tm.assert_series_equal(result, expected)

        result = df.resample("H").mean()["a"].interpolate("cubic")
        tm.assert_series_equal(result, expected)

    def test_weekly_resample_buglet(self):
        # #1327
        rng = date_range('1/1/2000', freq='B', periods=20)
        ts = Series(np.random.randn(len(rng)), index=rng)

        resampled = ts.resample('W').mean()
        expected = ts.resample('W-SUN').mean()
        assert_series_equal(resampled, expected)

    def test_monthly_resample_error(self):
        # #1451
        dates = date_range('4/16/2012 20:00', periods=5000, freq='h')
        ts = Series(np.random.randn(len(dates)), index=dates)
        # it works!
        ts.resample('M')

    def test_nanosecond_resample_error(self):
        # GH 12307 - Values falls after last bin when
        # Resampling using pd.tseries.offsets.Nano as period
        start = 1443707890427
        exp_start = 1443707890400
        indx = pd.date_range(
            start=pd.to_datetime(start),
            periods=10,
            freq='100n'
        )
        ts = Series(range(len(indx)), index=indx)
        r = ts.resample(pd.tseries.offsets.Nano(100))
        result = r.agg('mean')

        exp_indx = pd.date_range(
            start=pd.to_datetime(exp_start),
            periods=10,
            freq='100n'
        )
        exp = Series(range(len(exp_indx)), index=exp_indx)

        assert_series_equal(result, exp)

    def test_resample_anchored_intraday(self, simple_date_range_series):
        # #1471, #1458

        rng = date_range('1/1/2012', '4/1/2012', freq='100min')
        df = DataFrame(rng.month, index=rng)

        result = df.resample('M').mean()
        expected = df.resample(
            'M', kind='period').mean().to_timestamp(how='end')
        expected.index += Timedelta(1, 'ns') - Timedelta(1, 'D')
        tm.assert_frame_equal(result, expected)

        result = df.resample('M', closed='left').mean()
        exp = df.tshift(1, freq='D').resample('M', kind='period').mean()
        exp = exp.to_timestamp(how='end')

        exp.index = exp.index + Timedelta(1, 'ns') - Timedelta(1, 'D')
        tm.assert_frame_equal(result, exp)

        rng = date_range('1/1/2012', '4/1/2012', freq='100min')
        df = DataFrame(rng.month, index=rng)

        result = df.resample('Q').mean()
        expected = df.resample(
            'Q', kind='period').mean().to_timestamp(how='end')
        expected.index += Timedelta(1, 'ns') - Timedelta(1, 'D')
        tm.assert_frame_equal(result, expected)

        result = df.resample('Q', closed='left').mean()
        expected = df.tshift(1, freq='D').resample('Q', kind='period',
                                                   closed='left').mean()
        expected = expected.to_timestamp(how='end')
        expected.index += Timedelta(1, 'ns') - Timedelta(1, 'D')
        tm.assert_frame_equal(result, expected)

        ts = simple_date_range_series('2012-04-29 23:00', '2012-04-30 5:00',
                                      freq='h')
        resampled = ts.resample('M').mean()
        assert len(resampled) == 1

    def test_resample_anchored_monthstart(self, simple_date_range_series):
        ts = simple_date_range_series('1/1/2000', '12/31/2002')

        freqs = ['MS', 'BMS', 'QS-MAR', 'AS-DEC', 'AS-JUN']

        for freq in freqs:
            ts.resample(freq).mean()

    def test_resample_anchored_multiday(self):
        # When resampling a range spanning multiple days, ensure that the
        # start date gets used to determine the offset.  Fixes issue where
        # a one day period is not a multiple of the frequency.
        #
        # See: https://github.com/pandas-dev/pandas/issues/8683

        index = pd.date_range(
            '2014-10-14 23:06:23.206', periods=3, freq='400L'
        ) | pd.date_range(
            '2014-10-15 23:00:00', periods=2, freq='2200L')

        s = Series(np.random.randn(5), index=index)

        # Ensure left closing works
        result = s.resample('2200L').mean()
        assert result.index[-1] == Timestamp('2014-10-15 23:00:02.000')

        # Ensure right closing works
        result = s.resample('2200L', label='right').mean()
        assert result.index[-1] == Timestamp('2014-10-15 23:00:04.200')

    def test_corner_cases(self, simple_period_range_series,
                          simple_date_range_series):
        # miscellaneous test coverage

        rng = date_range('1/1/2000', periods=12, freq='t')
        ts = Series(np.random.randn(len(rng)), index=rng)

        result = ts.resample('5t', closed='right', label='left').mean()
        ex_index = date_range('1999-12-31 23:55', periods=4, freq='5t')
        tm.assert_index_equal(result.index, ex_index)

        len0pts = simple_period_range_series(
            '2007-01', '2010-05', freq='M')[:0]
        # it works
        result = len0pts.resample('A-DEC').mean()
        assert len(result) == 0

        # resample to periods
        ts = simple_date_range_series(
            '2000-04-28', '2000-04-30 11:00', freq='h')
        result = ts.resample('M', kind='period').mean()
        assert len(result) == 1
        assert result.index[0] == Period('2000-04', freq='M')

    def test_anchored_lowercase_buglet(self):
        dates = date_range('4/16/2012 20:00', periods=50000, freq='s')
        ts = Series(np.random.randn(len(dates)), index=dates)
        # it works!
        ts.resample('d').mean()

    def test_upsample_apply_functions(self):
        # #1596
        rng = pd.date_range('2012-06-12', periods=4, freq='h')

        ts = Series(np.random.randn(len(rng)), index=rng)

        result = ts.resample('20min').aggregate(['mean', 'sum'])
        assert isinstance(result, DataFrame)

    def test_resample_not_monotonic(self):
        rng = pd.date_range('2012-06-12', periods=200, freq='h')
        ts = Series(np.random.randn(len(rng)), index=rng)

        ts = ts.take(np.random.permutation(len(ts)))

        result = ts.resample('D').sum()
        exp = ts.sort_index().resample('D').sum()
        assert_series_equal(result, exp)

    def test_resample_median_bug_1688(self):

        for dtype in ['int64', 'int32', 'float64', 'float32']:
            df = DataFrame([1, 2], index=[datetime(2012, 1, 1, 0, 0, 0),
                                          datetime(2012, 1, 1, 0, 5, 0)],
                           dtype=dtype)

            result = df.resample("T").apply(lambda x: x.mean())
            exp = df.asfreq('T')
            tm.assert_frame_equal(result, exp)

            result = df.resample("T").median()
            exp = df.asfreq('T')
            tm.assert_frame_equal(result, exp)

    def test_how_lambda_functions(self, simple_date_range_series):

        ts = simple_date_range_series('1/1/2000', '4/1/2000')

        result = ts.resample('M').apply(lambda x: x.mean())
        exp = ts.resample('M').mean()
        tm.assert_series_equal(result, exp)

        foo_exp = ts.resample('M').mean()
        foo_exp.name = 'foo'
        bar_exp = ts.resample('M').std()
        bar_exp.name = 'bar'

        result = ts.resample('M').apply(
            [lambda x: x.mean(), lambda x: x.std(ddof=1)])
        result.columns = ['foo', 'bar']
        tm.assert_series_equal(result['foo'], foo_exp)
        tm.assert_series_equal(result['bar'], bar_exp)

        # this is a MI Series, so comparing the names of the results
        # doesn't make sense
        result = ts.resample('M').aggregate({'foo': lambda x: x.mean(),
                                             'bar': lambda x: x.std(ddof=1)})
        tm.assert_series_equal(result['foo'], foo_exp, check_names=False)
        tm.assert_series_equal(result['bar'], bar_exp, check_names=False)

    def test_resample_unequal_times(self):
        # #1772
        start = datetime(1999, 3, 1, 5)
        # end hour is less than start
        end = datetime(2012, 7, 31, 4)
        bad_ind = date_range(start, end, freq="30min")
        df = DataFrame({'close': 1}, index=bad_ind)

        # it works!
        df.resample('AS').sum()

    def test_resample_consistency(self):

        # GH 6418
        # resample with bfill / limit / reindex consistency

        i30 = pd.date_range('2002-02-02', periods=4, freq='30T')
        s = Series(np.arange(4.), index=i30)
        s[2] = np.NaN

        # Upsample by factor 3 with reindex() and resample() methods:
        i10 = pd.date_range(i30[0], i30[-1], freq='10T')

        s10 = s.reindex(index=i10, method='bfill')
        s10_2 = s.reindex(index=i10, method='bfill', limit=2)
        rl = s.reindex_like(s10, method='bfill', limit=2)
        r10_2 = s.resample('10Min').bfill(limit=2)
        r10 = s.resample('10Min').bfill()

        # s10_2, r10, r10_2, rl should all be equal
        assert_series_equal(s10_2, r10)
        assert_series_equal(s10_2, r10_2)
        assert_series_equal(s10_2, rl)

    def test_resample_timegrouper(self):
        # GH 7227
        dates1 = [datetime(2014, 10, 1), datetime(2014, 9, 3),
                  datetime(2014, 11, 5), datetime(2014, 9, 5),
                  datetime(2014, 10, 8), datetime(2014, 7, 15)]

        dates2 = dates1[:2] + [pd.NaT] + dates1[2:4] + [pd.NaT] + dates1[4:]
        dates3 = [pd.NaT] + dates1 + [pd.NaT]

        for dates in [dates1, dates2, dates3]:
            df = DataFrame(dict(A=dates, B=np.arange(len(dates))))
            result = df.set_index('A').resample('M').count()
            exp_idx = pd.DatetimeIndex(['2014-07-31', '2014-08-31',
                                        '2014-09-30',
                                        '2014-10-31', '2014-11-30'],
                                       freq='M', name='A')
            expected = DataFrame({'B': [1, 0, 2, 2, 1]}, index=exp_idx)
            assert_frame_equal(result, expected)

            result = df.groupby(pd.Grouper(freq='M', key='A')).count()
            assert_frame_equal(result, expected)

            df = DataFrame(dict(A=dates, B=np.arange(len(dates)), C=np.arange(
                len(dates))))
            result = df.set_index('A').resample('M').count()
            expected = DataFrame({'B': [1, 0, 2, 2, 1], 'C': [1, 0, 2, 2, 1]},
                                 index=exp_idx, columns=['B', 'C'])
            assert_frame_equal(result, expected)

            result = df.groupby(pd.Grouper(freq='M', key='A')).count()
            assert_frame_equal(result, expected)

    def test_resample_nunique(self):

        # GH 12352
        df = DataFrame({
            'ID': {Timestamp('2015-06-05 00:00:00'): '0010100903',
                   Timestamp('2015-06-08 00:00:00'): '0010150847'},
            'DATE': {Timestamp('2015-06-05 00:00:00'): '2015-06-05',
                     Timestamp('2015-06-08 00:00:00'): '2015-06-08'}})
        r = df.resample('D')
        g = df.groupby(pd.Grouper(freq='D'))
        expected = df.groupby(pd.Grouper(freq='D')).ID.apply(lambda x:
                                                             x.nunique())
        assert expected.name == 'ID'

        for t in [r, g]:
            result = r.ID.nunique()
            assert_series_equal(result, expected)

        result = df.ID.resample('D').nunique()
        assert_series_equal(result, expected)

        result = df.ID.groupby(pd.Grouper(freq='D')).nunique()
        assert_series_equal(result, expected)

    def test_resample_nunique_with_date_gap(self):
        # GH 13453
        index = pd.date_range('1-1-2000', '2-15-2000', freq='h')
        index2 = pd.date_range('4-15-2000', '5-15-2000', freq='h')
        index3 = index.append(index2)
        s = Series(range(len(index3)), index=index3, dtype='int64')
        r = s.resample('M')

        # Since all elements are unique, these should all be the same
        results = [
            r.count(),
            r.nunique(),
            r.agg(Series.nunique),
            r.agg('nunique')
        ]

        assert_series_equal(results[0], results[1])
        assert_series_equal(results[0], results[2])
        assert_series_equal(results[0], results[3])

    @pytest.mark.parametrize('n', [10000, 100000])
    @pytest.mark.parametrize('k', [10, 100, 1000])
    def test_resample_group_info(self, n, k):
        # GH10914
        dr = date_range(start='2015-08-27', periods=n // 10, freq='T')
        ts = Series(np.random.randint(0, n // k, n).astype('int64'),
                    index=np.random.choice(dr, n))

        left = ts.resample('30T').nunique()
        ix = date_range(start=ts.index.min(), end=ts.index.max(),
                        freq='30T')

        vals = ts.values
        bins = np.searchsorted(ix.values, ts.index, side='right')

        sorter = np.lexsort((vals, bins))
        vals, bins = vals[sorter], bins[sorter]

        mask = np.r_[True, vals[1:] != vals[:-1]]
        mask |= np.r_[True, bins[1:] != bins[:-1]]

        arr = np.bincount(bins[mask] - 1,
                          minlength=len(ix)).astype('int64', copy=False)
        right = Series(arr, index=ix)

        assert_series_equal(left, right)

    def test_resample_size(self):
        n = 10000
        dr = date_range('2015-09-19', periods=n, freq='T')
        ts = Series(np.random.randn(n), index=np.random.choice(dr, n))

        left = ts.resample('7T').size()
        ix = date_range(start=left.index.min(), end=ts.index.max(), freq='7T')

        bins = np.searchsorted(ix.values, ts.index.values, side='right')
        val = np.bincount(bins, minlength=len(ix) + 1)[1:].astype('int64',
                                                                  copy=False)

        right = Series(val, index=ix)
        assert_series_equal(left, right)

    def test_resample_across_dst(self):
        # The test resamples a DatetimeIndex with values before and after a
        # DST change
        # Issue: 14682

        # The DatetimeIndex we will start with
        # (note that DST happens at 03:00+02:00 -> 02:00+01:00)
        # 2016-10-30 02:23:00+02:00, 2016-10-30 02:23:00+01:00
        df1 = DataFrame([1477786980, 1477790580], columns=['ts'])
        dti1 = DatetimeIndex(pd.to_datetime(df1.ts, unit='s')
                             .dt.tz_localize('UTC')
                             .dt.tz_convert('Europe/Madrid'))

        # The expected DatetimeIndex after resampling.
        # 2016-10-30 02:00:00+02:00, 2016-10-30 02:00:00+01:00
        df2 = DataFrame([1477785600, 1477789200], columns=['ts'])
        dti2 = DatetimeIndex(pd.to_datetime(df2.ts, unit='s')
                             .dt.tz_localize('UTC')
                             .dt.tz_convert('Europe/Madrid'))
        df = DataFrame([5, 5], index=dti1)

        result = df.resample(rule='H').sum()
        expected = DataFrame([5, 5], index=dti2)

        assert_frame_equal(result, expected)

    def test_resample_dst_anchor(self):
        # 5172
        dti = DatetimeIndex([datetime(2012, 11, 4, 23)], tz='US/Eastern')
        df = DataFrame([5], index=dti)
        assert_frame_equal(df.resample(rule='CD').sum(),
                           DataFrame([5], index=df.index.normalize()))
        df.resample(rule='MS').sum()
        assert_frame_equal(
            df.resample(rule='MS').sum(),
            DataFrame([5], index=DatetimeIndex([datetime(2012, 11, 1)],
                                               tz='US/Eastern')))

        dti = date_range('2013-09-30', '2013-11-02', freq='30Min',
                         tz='Europe/Paris')
        values = range(dti.size)
        df = DataFrame({"a": values,
                        "b": values,
                        "c": values}, index=dti, dtype='int64')
        how = {"a": "min", "b": "max", "c": "count"}

        assert_frame_equal(
            df.resample("W-MON").agg(how)[["a", "b", "c"]],
            DataFrame({"a": [0, 48, 384, 720, 1056, 1394],
                       "b": [47, 383, 719, 1055, 1393, 1586],
                       "c": [48, 336, 336, 336, 338, 193]},
                      index=date_range('9/30/2013', '11/4/2013',
                                       freq='W-MON', tz='Europe/Paris')),
            'W-MON Frequency')

        assert_frame_equal(
            df.resample("2W-MON").agg(how)[["a", "b", "c"]],
            DataFrame({"a": [0, 48, 720, 1394],
                       "b": [47, 719, 1393, 1586],
                       "c": [48, 672, 674, 193]},
                      index=date_range('9/30/2013', '11/11/2013',
                                       freq='2W-MON', tz='Europe/Paris')),
            '2W-MON Frequency')

        assert_frame_equal(
            df.resample("MS").agg(how)[["a", "b", "c"]],
            DataFrame({"a": [0, 48, 1538],
                       "b": [47, 1537, 1586],
                       "c": [48, 1490, 49]},
                      index=date_range('9/1/2013', '11/1/2013',
                                       freq='MS', tz='Europe/Paris')),
            'MS Frequency')

        assert_frame_equal(
            df.resample("2MS").agg(how)[["a", "b", "c"]],
            DataFrame({"a": [0, 1538],
                       "b": [1537, 1586],
                       "c": [1538, 49]},
                      index=date_range('9/1/2013', '11/1/2013',
                                       freq='2MS', tz='Europe/Paris')),
            '2MS Frequency')

        df_daily = df['10/26/2013':'10/29/2013']
        assert_frame_equal(
            df_daily.resample("CD").agg({"a": "min", "b": "max", "c": "count"})
            [["a", "b", "c"]],
            DataFrame({"a": [1248, 1296, 1346, 1394],
                       "b": [1295, 1345, 1393, 1441],
                       "c": [48, 50, 48, 48]},
                      index=date_range('10/26/2013', '10/29/2013',
                                       freq='CD', tz='Europe/Paris')),
            'CD Frequency')

    def test_downsample_across_dst(self):
        # GH 8531
        tz = pytz.timezone('Europe/Berlin')
        dt = datetime(2014, 10, 26)
        dates = date_range(tz.localize(dt), periods=4, freq='2H')
        result = Series(5, index=dates).resample('H').mean()
        expected = Series([5., np.nan] * 3 + [5.],
                          index=date_range(tz.localize(dt), periods=7,
                                           freq='H'))
        tm.assert_series_equal(result, expected)

    def test_downsample_across_dst_weekly(self):
        # GH 9119, GH 21459
        df = DataFrame(index=DatetimeIndex([
            '2017-03-25', '2017-03-26', '2017-03-27',
            '2017-03-28', '2017-03-29'
        ], tz='Europe/Amsterdam'),
            data=[11, 12, 13, 14, 15])
        result = df.resample('1W').sum()
        expected = DataFrame([23, 42], index=pd.DatetimeIndex([
            '2017-03-26', '2017-04-02'
        ], tz='Europe/Amsterdam'))
        tm.assert_frame_equal(result, expected)

        idx = pd.date_range("2013-04-01", "2013-05-01", tz='Europe/London',
                            freq='H')
        s = Series(index=idx)
        result = s.resample('W').mean()
        expected = Series(index=pd.date_range(
            '2013-04-07', freq='W', periods=5, tz='Europe/London'
        ))
        tm.assert_series_equal(result, expected)

    def test_resample_with_nat(self):
        # GH 13020
        index = DatetimeIndex([pd.NaT,
                               '1970-01-01 00:00:00',
                               pd.NaT,
                               '1970-01-01 00:00:01',
                               '1970-01-01 00:00:02'])
        frame = DataFrame([2, 3, 5, 7, 11], index=index)

        index_1s = DatetimeIndex(['1970-01-01 00:00:00',
                                  '1970-01-01 00:00:01',
                                  '1970-01-01 00:00:02'])
        frame_1s = DataFrame([3, 7, 11], index=index_1s)
        assert_frame_equal(frame.resample('1s').mean(), frame_1s)

        index_2s = DatetimeIndex(['1970-01-01 00:00:00',
                                  '1970-01-01 00:00:02'])
        frame_2s = DataFrame([5, 11], index=index_2s)
        assert_frame_equal(frame.resample('2s').mean(), frame_2s)

        index_3s = DatetimeIndex(['1970-01-01 00:00:00'])
        frame_3s = DataFrame([7], index=index_3s)
        assert_frame_equal(frame.resample('3s').mean(), frame_3s)

        assert_frame_equal(frame.resample('60s').mean(), frame_3s)

    def test_resample_timedelta_values(self):
        # GH 13119
        # check that timedelta dtype is preserved when NaT values are
        # introduced by the resampling

        times = timedelta_range('1 day', '4 day', freq='4D')
        df = DataFrame({'time': times}, index=times)

        times2 = timedelta_range('1 day', '4 day', freq='2D')
        exp = Series(times2, index=times2, name='time')
        exp.iloc[1] = pd.NaT

        res = df.resample('2D').first()['time']
        tm.assert_series_equal(res, exp)
        res = df['time'].resample('2D').first()
        tm.assert_series_equal(res, exp)

    def test_resample_datetime_values(self):
        # GH 13119
        # check that datetime dtype is preserved when NaT values are
        # introduced by the resampling

        dates = [datetime(2016, 1, 15), datetime(2016, 1, 19)]
        df = DataFrame({'timestamp': dates}, index=dates)

        exp = Series([datetime(2016, 1, 15), pd.NaT, datetime(2016, 1, 19)],
                     index=date_range('2016-01-15', periods=3, freq='2D'),
                     name='timestamp')

        res = df.resample('2D').first()['timestamp']
        tm.assert_series_equal(res, exp)
        res = df['timestamp'].resample('2D').first()
        tm.assert_series_equal(res, exp)

    def test_resample_apply_with_additional_args(self):
        # GH 14615
        def f(data, add_arg):
            return np.mean(data) * add_arg

        multiplier = 10
        result = self.series.resample('D').apply(f, multiplier)
        expected = self.series.resample('D').mean().multiply(multiplier)
        tm.assert_series_equal(result, expected)

        # Testing as kwarg
        result = self.series.resample('D').apply(f, add_arg=multiplier)
        expected = self.series.resample('D').mean().multiply(multiplier)
        tm.assert_series_equal(result, expected)

        # Testing dataframe
        df = pd.DataFrame({"A": 1, "B": 2},
                          index=pd.date_range('2017', periods=10))
        result = df.groupby("A").resample("D").agg(f, multiplier)
        expected = df.groupby("A").resample('D').mean().multiply(multiplier)
        assert_frame_equal(result, expected)