# -*- coding: utf-8 -*-

""" test where we are determining what we are grouping, or getting groups """

import pytest

from warnings import catch_warnings
from pandas import (date_range, Timestamp,
                    Index, MultiIndex, DataFrame, Series, CategoricalIndex)
from pandas.util.testing import (assert_panel_equal, assert_frame_equal,
                                 assert_series_equal, assert_almost_equal)
from pandas.core.groupby.groupby import Grouping
from pandas.compat import lrange, long

from pandas import compat
import numpy as np

import pandas.util.testing as tm
import pandas as pd


# selection
# --------------------------------

class TestSelection():

    def test_select_bad_cols(self):
        df = DataFrame([[1, 2]], columns=['A', 'B'])
        g = df.groupby('A')
        pytest.raises(KeyError, g.__getitem__, ['C'])  # g[['C']]

        pytest.raises(KeyError, g.__getitem__, ['A', 'C'])  # g[['A', 'C']]
        with tm.assert_raises_regex(KeyError, '^[^A]+$'):
            # A should not be referenced as a bad column...
            # will have to rethink regex if you change message!
            g[['A', 'C']]

    def test_groupby_duplicated_column_errormsg(self):
        # GH7511
        df = DataFrame(columns=['A', 'B', 'A', 'C'],
                       data=[range(4), range(2, 6), range(0, 8, 2)])

        pytest.raises(ValueError, df.groupby, 'A')
        pytest.raises(ValueError, df.groupby, ['A', 'B'])

        grouped = df.groupby('B')
        c = grouped.count()
        assert c.columns.nlevels == 1
        assert c.columns.size == 3

    def test_column_select_via_attr(self, df):
        result = df.groupby('A').C.sum()
        expected = df.groupby('A')['C'].sum()
        assert_series_equal(result, expected)

        df['mean'] = 1.5
        result = df.groupby('A').mean()
        expected = df.groupby('A').agg(np.mean)
        assert_frame_equal(result, expected)

    def test_getitem_list_of_columns(self):
        df = DataFrame(
            {'A': ['foo', 'bar', 'foo', 'bar', 'foo', 'bar', 'foo', 'foo'],
             'B': ['one', 'one', 'two', 'three', 'two', 'two', 'one', 'three'],
             'C': np.random.randn(8),
             'D': np.random.randn(8),
             'E': np.random.randn(8)})

        result = df.groupby('A')[['C', 'D']].mean()
        result2 = df.groupby('A')['C', 'D'].mean()
        result3 = df.groupby('A')[df.columns[2:4]].mean()

        expected = df.loc[:, ['A', 'C', 'D']].groupby('A').mean()

        assert_frame_equal(result, expected)
        assert_frame_equal(result2, expected)
        assert_frame_equal(result3, expected)

    def test_getitem_numeric_column_names(self):
        # GH #13731
        df = DataFrame({0: list('abcd') * 2,
                        2: np.random.randn(8),
                        4: np.random.randn(8),
                        6: np.random.randn(8)})
        result = df.groupby(0)[df.columns[1:3]].mean()
        result2 = df.groupby(0)[2, 4].mean()
        result3 = df.groupby(0)[[2, 4]].mean()

        expected = df.loc[:, [0, 2, 4]].groupby(0).mean()

        assert_frame_equal(result, expected)
        assert_frame_equal(result2, expected)
        assert_frame_equal(result3, expected)


# grouping
# --------------------------------

class TestGrouping():

    def test_grouper_index_types(self):
        # related GH5375
        # groupby misbehaving when using a Floatlike index
        df = DataFrame(np.arange(10).reshape(5, 2), columns=list('AB'))
        for index in [tm.makeFloatIndex, tm.makeStringIndex,
                      tm.makeUnicodeIndex, tm.makeIntIndex, tm.makeDateIndex,
                      tm.makePeriodIndex]:

            df.index = index(len(df))
            df.groupby(list('abcde')).apply(lambda x: x)

            df.index = list(reversed(df.index.tolist()))
            df.groupby(list('abcde')).apply(lambda x: x)

    def test_grouper_multilevel_freq(self):

        # GH 7885
        # with level and freq specified in a pd.Grouper
        from datetime import date, timedelta
        d0 = date.today() - timedelta(days=14)
        dates = date_range(d0, date.today())
        date_index = pd.MultiIndex.from_product(
            [dates, dates], names=['foo', 'bar'])
        df = pd.DataFrame(np.random.randint(0, 100, 225), index=date_index)

        # Check string level
        expected = df.reset_index().groupby([pd.Grouper(
            key='foo', freq='W'), pd.Grouper(key='bar', freq='W')]).sum()
        # reset index changes columns dtype to object
        expected.columns = pd.Index([0], dtype='int64')

        result = df.groupby([pd.Grouper(level='foo', freq='W'), pd.Grouper(
            level='bar', freq='W')]).sum()
        assert_frame_equal(result, expected)

        # Check integer level
        result = df.groupby([pd.Grouper(level=0, freq='W'), pd.Grouper(
            level=1, freq='W')]).sum()
        assert_frame_equal(result, expected)

    def test_grouper_creation_bug(self):

        # GH 8795
        df = DataFrame({'A': [0, 0, 1, 1, 2, 2], 'B': [1, 2, 3, 4, 5, 6]})
        g = df.groupby('A')
        expected = g.sum()

        g = df.groupby(pd.Grouper(key='A'))
        result = g.sum()
        assert_frame_equal(result, expected)

        result = g.apply(lambda x: x.sum())
        assert_frame_equal(result, expected)

        g = df.groupby(pd.Grouper(key='A', axis=0))
        result = g.sum()
        assert_frame_equal(result, expected)

        # GH14334
        # pd.Grouper(key=...) may be passed in a list
        df = DataFrame({'A': [0, 0, 0, 1, 1, 1],
                        'B': [1, 1, 2, 2, 3, 3],
                        'C': [1, 2, 3, 4, 5, 6]})
        # Group by single column
        expected = df.groupby('A').sum()
        g = df.groupby([pd.Grouper(key='A')])
        result = g.sum()
        assert_frame_equal(result, expected)

        # Group by two columns
        # using a combination of strings and Grouper objects
        expected = df.groupby(['A', 'B']).sum()

        # Group with two Grouper objects
        g = df.groupby([pd.Grouper(key='A'), pd.Grouper(key='B')])
        result = g.sum()
        assert_frame_equal(result, expected)

        # Group with a string and a Grouper object
        g = df.groupby(['A', pd.Grouper(key='B')])
        result = g.sum()
        assert_frame_equal(result, expected)

        # Group with a Grouper object and a string
        g = df.groupby([pd.Grouper(key='A'), 'B'])
        result = g.sum()
        assert_frame_equal(result, expected)

        # GH8866
        s = Series(np.arange(8, dtype='int64'),
                   index=pd.MultiIndex.from_product(
                       [list('ab'), range(2),
                        date_range('20130101', periods=2)],
                       names=['one', 'two', 'three']))
        result = s.groupby(pd.Grouper(level='three', freq='M')).sum()
        expected = Series([28], index=Index(
            [Timestamp('2013-01-31')], freq='M', name='three'))
        assert_series_equal(result, expected)

        # just specifying a level breaks
        result = s.groupby(pd.Grouper(level='one')).sum()
        expected = s.groupby(level='one').sum()
        assert_series_equal(result, expected)

    def test_grouper_column_and_index(self):
        # GH 14327

        # Grouping a multi-index frame by a column and an index level should
        # be equivalent to resetting the index and grouping by two columns
        idx = pd.MultiIndex.from_tuples([('a', 1), ('a', 2), ('a', 3),
                                         ('b', 1), ('b', 2), ('b', 3)])
        idx.names = ['outer', 'inner']
        df_multi = pd.DataFrame({"A": np.arange(6),
                                 'B': ['one', 'one', 'two',
                                       'two', 'one', 'one']},
                                index=idx)
        result = df_multi.groupby(['B', pd.Grouper(level='inner')]).mean()
        expected = df_multi.reset_index().groupby(['B', 'inner']).mean()
        assert_frame_equal(result, expected)

        # Test the reverse grouping order
        result = df_multi.groupby([pd.Grouper(level='inner'), 'B']).mean()
        expected = df_multi.reset_index().groupby(['inner', 'B']).mean()
        assert_frame_equal(result, expected)

        # Grouping a single-index frame by a column and the index should
        # be equivalent to resetting the index and grouping by two columns
        df_single = df_multi.reset_index('outer')
        result = df_single.groupby(['B', pd.Grouper(level='inner')]).mean()
        expected = df_single.reset_index().groupby(['B', 'inner']).mean()
        assert_frame_equal(result, expected)

        # Test the reverse grouping order
        result = df_single.groupby([pd.Grouper(level='inner'), 'B']).mean()
        expected = df_single.reset_index().groupby(['inner', 'B']).mean()
        assert_frame_equal(result, expected)

    def test_groupby_levels_and_columns(self):
        # GH9344, GH9049
        idx_names = ['x', 'y']
        idx = pd.MultiIndex.from_tuples(
            [(1, 1), (1, 2), (3, 4), (5, 6)], names=idx_names)
        df = pd.DataFrame(np.arange(12).reshape(-1, 3), index=idx)

        by_levels = df.groupby(level=idx_names).mean()
        # reset_index changes columns dtype to object
        by_columns = df.reset_index().groupby(idx_names).mean()

        tm.assert_frame_equal(by_levels, by_columns, check_column_type=False)

        by_columns.columns = pd.Index(by_columns.columns, dtype=np.int64)
        tm.assert_frame_equal(by_levels, by_columns)

    def test_groupby_categorical_index_and_columns(self, observed):
        # GH18432
        columns = ['A', 'B', 'A', 'B']
        categories = ['B', 'A']
        data = np.ones((5, 4), int)
        cat_columns = CategoricalIndex(columns,
                                       categories=categories,
                                       ordered=True)
        df = DataFrame(data=data, columns=cat_columns)
        result = df.groupby(axis=1, level=0, observed=observed).sum()
        expected_data = 2 * np.ones((5, 2), int)

        if observed:
            # if we are not-observed we undergo a reindex
            # so need to adjust the output as our expected sets us up
            # to be non-observed
            expected_columns = CategoricalIndex(['A', 'B'],
                                                categories=categories,
                                                ordered=True)
        else:
            expected_columns = CategoricalIndex(categories,
                                                categories=categories,
                                                ordered=True)
        expected = DataFrame(data=expected_data, columns=expected_columns)
        assert_frame_equal(result, expected)

        # test transposed version
        df = DataFrame(data.T, index=cat_columns)
        result = df.groupby(axis=0, level=0, observed=observed).sum()
        expected = DataFrame(data=expected_data.T, index=expected_columns)
        assert_frame_equal(result, expected)

    def test_grouper_getting_correct_binner(self):

        # GH 10063
        # using a non-time-based grouper and a time-based grouper
        # and specifying levels
        df = DataFrame({'A': 1}, index=pd.MultiIndex.from_product(
            [list('ab'), date_range('20130101', periods=80)], names=['one',
                                                                     'two']))
        result = df.groupby([pd.Grouper(level='one'), pd.Grouper(
            level='two', freq='M')]).sum()
        expected = DataFrame({'A': [31, 28, 21, 31, 28, 21]},
                             index=MultiIndex.from_product(
                                 [list('ab'),
                                  date_range('20130101', freq='M', periods=3)],
                                 names=['one', 'two']))
        assert_frame_equal(result, expected)

    def test_grouper_iter(self, df):
        assert sorted(df.groupby('A').grouper) == ['bar', 'foo']

    def test_empty_groups(self, df):
        # see gh-1048
        pytest.raises(ValueError, df.groupby, [])

    def test_groupby_grouper(self, df):
        grouped = df.groupby('A')

        result = df.groupby(grouped.grouper).mean()
        expected = grouped.mean()
        tm.assert_frame_equal(result, expected)

    def test_groupby_dict_mapping(self):
        # GH #679
        from pandas import Series
        s = Series({'T1': 5})
        result = s.groupby({'T1': 'T2'}).agg(sum)
        expected = s.groupby(['T2']).agg(sum)
        assert_series_equal(result, expected)

        s = Series([1., 2., 3., 4.], index=list('abcd'))
        mapping = {'a': 0, 'b': 0, 'c': 1, 'd': 1}

        result = s.groupby(mapping).mean()
        result2 = s.groupby(mapping).agg(np.mean)
        expected = s.groupby([0, 0, 1, 1]).mean()
        expected2 = s.groupby([0, 0, 1, 1]).mean()
        assert_series_equal(result, expected)
        assert_series_equal(result, result2)
        assert_series_equal(result, expected2)

    def test_groupby_grouper_f_sanity_checked(self):
        dates = date_range('01-Jan-2013', periods=12, freq='MS')
        ts = Series(np.random.randn(12), index=dates)

        # GH3035
        # index.map is used to apply grouper to the index
        # if it fails on the elements, map tries it on the entire index as
        # a sequence. That can yield invalid results that cause trouble
        # down the line.
        # the surprise comes from using key[0:6] rather then str(key)[0:6]
        # when the elements are Timestamp.
        # the result is Index[0:6], very confusing.

        pytest.raises(AssertionError, ts.groupby, lambda key: key[0:6])

    def test_grouping_error_on_multidim_input(self, df):
        pytest.raises(ValueError,
                      Grouping, df.index, df[['A', 'A']])

    def test_multiindex_passthru(self):

        # GH 7997
        # regression from 0.14.1
        df = pd.DataFrame([[1, 2, 3], [4, 5, 6], [7, 8, 9]])
        df.columns = pd.MultiIndex.from_tuples([(0, 1), (1, 1), (2, 1)])

        result = df.groupby(axis=1, level=[0, 1]).first()
        assert_frame_equal(result, df)

    def test_multiindex_negative_level(self, mframe):
        # GH 13901
        result = mframe.groupby(level=-1).sum()
        expected = mframe.groupby(level='second').sum()
        assert_frame_equal(result, expected)

        result = mframe.groupby(level=-2).sum()
        expected = mframe.groupby(level='first').sum()
        assert_frame_equal(result, expected)

        result = mframe.groupby(level=[-2, -1]).sum()
        expected = mframe
        assert_frame_equal(result, expected)

        result = mframe.groupby(level=[-1, 'first']).sum()
        expected = mframe.groupby(level=['second', 'first']).sum()
        assert_frame_equal(result, expected)

    def test_multifunc_select_col_integer_cols(self, df):
        df.columns = np.arange(len(df.columns))

        # it works!
        df.groupby(1, as_index=False)[2].agg({'Q': np.mean})

    def test_multiindex_columns_empty_level(self):
        lst = [['count', 'values'], ['to filter', '']]
        midx = MultiIndex.from_tuples(lst)

        df = DataFrame([[long(1), 'A']], columns=midx)

        grouped = df.groupby('to filter').groups
        assert grouped['A'] == [0]

        grouped = df.groupby([('to filter', '')]).groups
        assert grouped['A'] == [0]

        df = DataFrame([[long(1), 'A'], [long(2), 'B']], columns=midx)

        expected = df.groupby('to filter').groups
        result = df.groupby([('to filter', '')]).groups
        assert result == expected

        df = DataFrame([[long(1), 'A'], [long(2), 'A']], columns=midx)

        expected = df.groupby('to filter').groups
        result = df.groupby([('to filter', '')]).groups
        tm.assert_dict_equal(result, expected)

    def test_groupby_multiindex_tuple(self):
        # GH 17979
        df = pd.DataFrame([[1, 2, 3, 4], [3, 4, 5, 6], [1, 4, 2, 3]],
                          columns=pd.MultiIndex.from_arrays(
                              [['a', 'b', 'b', 'c'],
                               [1, 1, 2, 2]]))
        expected = df.groupby([('b', 1)]).groups
        result = df.groupby(('b', 1)).groups
        tm.assert_dict_equal(expected, result)

        df2 = pd.DataFrame(df.values,
                           columns=pd.MultiIndex.from_arrays(
                               [['a', 'b', 'b', 'c'],
                                ['d', 'd', 'e', 'e']]))
        expected = df2.groupby([('b', 'd')]).groups
        result = df.groupby(('b', 1)).groups
        tm.assert_dict_equal(expected, result)

        df3 = pd.DataFrame(df.values,
                           columns=[('a', 'd'), ('b', 'd'), ('b', 'e'), 'c'])
        expected = df3.groupby([('b', 'd')]).groups
        result = df.groupby(('b', 1)).groups
        tm.assert_dict_equal(expected, result)

    @pytest.mark.parametrize('sort', [True, False])
    def test_groupby_level(self, sort, mframe, df):
        # GH 17537
        frame = mframe
        deleveled = frame.reset_index()

        result0 = frame.groupby(level=0, sort=sort).sum()
        result1 = frame.groupby(level=1, sort=sort).sum()

        expected0 = frame.groupby(deleveled['first'].values, sort=sort).sum()
        expected1 = frame.groupby(deleveled['second'].values, sort=sort).sum()

        expected0.index.name = 'first'
        expected1.index.name = 'second'

        assert result0.index.name == 'first'
        assert result1.index.name == 'second'

        assert_frame_equal(result0, expected0)
        assert_frame_equal(result1, expected1)
        assert result0.index.name == frame.index.names[0]
        assert result1.index.name == frame.index.names[1]

        # groupby level name
        result0 = frame.groupby(level='first', sort=sort).sum()
        result1 = frame.groupby(level='second', sort=sort).sum()
        assert_frame_equal(result0, expected0)
        assert_frame_equal(result1, expected1)

        # axis=1

        result0 = frame.T.groupby(level=0, axis=1, sort=sort).sum()
        result1 = frame.T.groupby(level=1, axis=1, sort=sort).sum()
        assert_frame_equal(result0, expected0.T)
        assert_frame_equal(result1, expected1.T)

        # raise exception for non-MultiIndex
        pytest.raises(ValueError, df.groupby, level=1)

    def test_groupby_level_index_names(self):
        # GH4014 this used to raise ValueError since 'exp'>1 (in py2)
        df = DataFrame({'exp': ['A'] * 3 + ['B'] * 3,
                        'var1': lrange(6), }).set_index('exp')
        df.groupby(level='exp')
        pytest.raises(ValueError, df.groupby, level='foo')

    @pytest.mark.parametrize('sort', [True, False])
    def test_groupby_level_with_nas(self, sort):
        # GH 17537
        index = MultiIndex(levels=[[1, 0], [0, 1, 2, 3]],
                           labels=[[1, 1, 1, 1, 0, 0, 0, 0], [0, 1, 2, 3, 0, 1,
                                                              2, 3]])

        # factorizing doesn't confuse things
        s = Series(np.arange(8.), index=index)
        result = s.groupby(level=0, sort=sort).sum()
        expected = Series([6., 22.], index=[0, 1])
        assert_series_equal(result, expected)

        index = MultiIndex(levels=[[1, 0], [0, 1, 2, 3]],
                           labels=[[1, 1, 1, 1, -1, 0, 0, 0], [0, 1, 2, 3, 0,
                                                               1, 2, 3]])

        # factorizing doesn't confuse things
        s = Series(np.arange(8.), index=index)
        result = s.groupby(level=0, sort=sort).sum()
        expected = Series([6., 18.], index=[0.0, 1.0])
        assert_series_equal(result, expected)

    def test_groupby_args(self, mframe):
        # PR8618 and issue 8015
        frame = mframe

        def j():
            frame.groupby()

        tm.assert_raises_regex(TypeError, "You have to supply one of "
                               "'by' and 'level'", j)

        def k():
            frame.groupby(by=None, level=None)

        tm.assert_raises_regex(TypeError, "You have to supply one of "
                               "'by' and 'level'", k)

    @pytest.mark.parametrize('sort,labels', [
        [True, [2, 2, 2, 0, 0, 1, 1, 3, 3, 3]],
        [False, [0, 0, 0, 1, 1, 2, 2, 3, 3, 3]]
    ])
    def test_level_preserve_order(self, sort, labels, mframe):
        # GH 17537
        grouped = mframe.groupby(level=0, sort=sort)
        exp_labels = np.array(labels, np.intp)
        assert_almost_equal(grouped.grouper.labels[0], exp_labels)

    def test_grouping_labels(self, mframe):
        grouped = mframe.groupby(mframe.index.get_level_values(0))
        exp_labels = np.array([2, 2, 2, 0, 0, 1, 1, 3, 3, 3], dtype=np.intp)
        assert_almost_equal(grouped.grouper.labels[0], exp_labels)


# get_group
# --------------------------------

class TestGetGroup():

    def test_get_group(self):
        with catch_warnings(record=True):
            wp = tm.makePanel()
            grouped = wp.groupby(lambda x: x.month, axis='major')

            gp = grouped.get_group(1)
            expected = wp.reindex(
                major=[x for x in wp.major_axis if x.month == 1])
            assert_panel_equal(gp, expected)

        # GH 5267
        # be datelike friendly
        df = DataFrame({'DATE': pd.to_datetime(
            ['10-Oct-2013', '10-Oct-2013', '10-Oct-2013', '11-Oct-2013',
             '11-Oct-2013', '11-Oct-2013']),
            'label': ['foo', 'foo', 'bar', 'foo', 'foo', 'bar'],
            'VAL': [1, 2, 3, 4, 5, 6]})

        g = df.groupby('DATE')
        key = list(g.groups)[0]
        result1 = g.get_group(key)
        result2 = g.get_group(Timestamp(key).to_pydatetime())
        result3 = g.get_group(str(Timestamp(key)))
        assert_frame_equal(result1, result2)
        assert_frame_equal(result1, result3)

        g = df.groupby(['DATE', 'label'])

        key = list(g.groups)[0]
        result1 = g.get_group(key)
        result2 = g.get_group((Timestamp(key[0]).to_pydatetime(), key[1]))
        result3 = g.get_group((str(Timestamp(key[0])), key[1]))
        assert_frame_equal(result1, result2)
        assert_frame_equal(result1, result3)

        # must pass a same-length tuple with multiple keys
        pytest.raises(ValueError, lambda: g.get_group('foo'))
        pytest.raises(ValueError, lambda: g.get_group(('foo')))
        pytest.raises(ValueError,
                      lambda: g.get_group(('foo', 'bar', 'baz')))

    def test_get_group_empty_bins(self, observed):

        d = pd.DataFrame([3, 1, 7, 6])
        bins = [0, 5, 10, 15]
        g = d.groupby(pd.cut(d[0], bins), observed=observed)

        # TODO: should prob allow a str of Interval work as well
        # IOW '(0, 5]'
        result = g.get_group(pd.Interval(0, 5))
        expected = DataFrame([3, 1], index=[0, 1])
        assert_frame_equal(result, expected)

        pytest.raises(KeyError, lambda: g.get_group(pd.Interval(10, 15)))

    def test_get_group_grouped_by_tuple(self):
        # GH 8121
        df = DataFrame([[(1, ), (1, 2), (1, ), (1, 2)]], index=['ids']).T
        gr = df.groupby('ids')
        expected = DataFrame({'ids': [(1, ), (1, )]}, index=[0, 2])
        result = gr.get_group((1, ))
        assert_frame_equal(result, expected)

        dt = pd.to_datetime(['2010-01-01', '2010-01-02', '2010-01-01',
                             '2010-01-02'])
        df = DataFrame({'ids': [(x, ) for x in dt]})
        gr = df.groupby('ids')
        result = gr.get_group(('2010-01-01', ))
        expected = DataFrame({'ids': [(dt[0], ), (dt[0], )]}, index=[0, 2])
        assert_frame_equal(result, expected)

    def test_groupby_with_empty(self):
        index = pd.DatetimeIndex(())
        data = ()
        series = pd.Series(data, index)
        grouper = pd.Grouper(freq='D')
        grouped = series.groupby(grouper)
        assert next(iter(grouped), None) is None

    def test_groupby_with_single_column(self):
        df = pd.DataFrame({'a': list('abssbab')})
        tm.assert_frame_equal(df.groupby('a').get_group('a'), df.iloc[[0, 5]])
        # GH 13530
        exp = pd.DataFrame([], index=pd.Index(['a', 'b', 's'], name='a'))
        tm.assert_frame_equal(df.groupby('a').count(), exp)
        tm.assert_frame_equal(df.groupby('a').sum(), exp)
        tm.assert_frame_equal(df.groupby('a').nth(1), exp)

    def test_gb_key_len_equal_axis_len(self):
            # GH16843
            # test ensures that index and column keys are recognized correctly
            # when number of keys equals axis length of groupby
            df = pd.DataFrame([['foo', 'bar', 'B', 1],
                               ['foo', 'bar', 'B', 2],
                               ['foo', 'baz', 'C', 3]],
                              columns=['first', 'second', 'third', 'one'])
            df = df.set_index(['first', 'second'])
            df = df.groupby(['first', 'second', 'third']).size()
            assert df.loc[('foo', 'bar', 'B')] == 2
            assert df.loc[('foo', 'baz', 'C')] == 1


# groups & iteration
# --------------------------------

class TestIteration():

    def test_groups(self, df):
        grouped = df.groupby(['A'])
        groups = grouped.groups
        assert groups is grouped.groups  # caching works

        for k, v in compat.iteritems(grouped.groups):
            assert (df.loc[v]['A'] == k).all()

        grouped = df.groupby(['A', 'B'])
        groups = grouped.groups
        assert groups is grouped.groups  # caching works

        for k, v in compat.iteritems(grouped.groups):
            assert (df.loc[v]['A'] == k[0]).all()
            assert (df.loc[v]['B'] == k[1]).all()

    def test_grouping_is_iterable(self, tsframe):
        # this code path isn't used anywhere else
        # not sure it's useful
        grouped = tsframe.groupby([lambda x: x.weekday(), lambda x: x.year])

        # test it works
        for g in grouped.grouper.groupings[0]:
            pass

    def test_multi_iter(self):
        s = Series(np.arange(6))
        k1 = np.array(['a', 'a', 'a', 'b', 'b', 'b'])
        k2 = np.array(['1', '2', '1', '2', '1', '2'])

        grouped = s.groupby([k1, k2])

        iterated = list(grouped)
        expected = [('a', '1', s[[0, 2]]), ('a', '2', s[[1]]),
                    ('b', '1', s[[4]]), ('b', '2', s[[3, 5]])]
        for i, ((one, two), three) in enumerate(iterated):
            e1, e2, e3 = expected[i]
            assert e1 == one
            assert e2 == two
            assert_series_equal(three, e3)

    def test_multi_iter_frame(self, three_group):
        k1 = np.array(['b', 'b', 'b', 'a', 'a', 'a'])
        k2 = np.array(['1', '2', '1', '2', '1', '2'])
        df = DataFrame({'v1': np.random.randn(6),
                        'v2': np.random.randn(6),
                        'k1': k1, 'k2': k2},
                       index=['one', 'two', 'three', 'four', 'five', 'six'])

        grouped = df.groupby(['k1', 'k2'])

        # things get sorted!
        iterated = list(grouped)
        idx = df.index
        expected = [('a', '1', df.loc[idx[[4]]]),
                    ('a', '2', df.loc[idx[[3, 5]]]),
                    ('b', '1', df.loc[idx[[0, 2]]]),
                    ('b', '2', df.loc[idx[[1]]])]
        for i, ((one, two), three) in enumerate(iterated):
            e1, e2, e3 = expected[i]
            assert e1 == one
            assert e2 == two
            assert_frame_equal(three, e3)

        # don't iterate through groups with no data
        df['k1'] = np.array(['b', 'b', 'b', 'a', 'a', 'a'])
        df['k2'] = np.array(['1', '1', '1', '2', '2', '2'])
        grouped = df.groupby(['k1', 'k2'])
        groups = {}
        for key, gp in grouped:
            groups[key] = gp
        assert len(groups) == 2

        # axis = 1
        three_levels = three_group.groupby(['A', 'B', 'C']).mean()
        grouped = three_levels.T.groupby(axis=1, level=(1, 2))
        for key, group in grouped:
            pass

    def test_multi_iter_panel(self):
        with catch_warnings(record=True):
            wp = tm.makePanel()
            grouped = wp.groupby([lambda x: x.month, lambda x: x.weekday()],
                                 axis=1)

            for (month, wd), group in grouped:
                exp_axis = [x
                            for x in wp.major_axis
                            if x.month == month and x.weekday() == wd]
                expected = wp.reindex(major=exp_axis)
                assert_panel_equal(group, expected)

    def test_dictify(self, df):
        dict(iter(df.groupby('A')))
        dict(iter(df.groupby(['A', 'B'])))
        dict(iter(df['C'].groupby(df['A'])))
        dict(iter(df['C'].groupby([df['A'], df['B']])))
        dict(iter(df.groupby('A')['C']))
        dict(iter(df.groupby(['A', 'B'])['C']))

    def test_groupby_with_small_elem(self):
        # GH 8542
        # length=2
        df = pd.DataFrame({'event': ['start', 'start'],
                           'change': [1234, 5678]},
                          index=pd.DatetimeIndex(['2014-09-10', '2013-10-10']))
        grouped = df.groupby([pd.Grouper(freq='M'), 'event'])
        assert len(grouped.groups) == 2
        assert grouped.ngroups == 2
        assert (pd.Timestamp('2014-09-30'), 'start') in grouped.groups
        assert (pd.Timestamp('2013-10-31'), 'start') in grouped.groups

        res = grouped.get_group((pd.Timestamp('2014-09-30'), 'start'))
        tm.assert_frame_equal(res, df.iloc[[0], :])
        res = grouped.get_group((pd.Timestamp('2013-10-31'), 'start'))
        tm.assert_frame_equal(res, df.iloc[[1], :])

        df = pd.DataFrame({'event': ['start', 'start', 'start'],
                           'change': [1234, 5678, 9123]},
                          index=pd.DatetimeIndex(['2014-09-10', '2013-10-10',
                                                  '2014-09-15']))
        grouped = df.groupby([pd.Grouper(freq='M'), 'event'])
        assert len(grouped.groups) == 2
        assert grouped.ngroups == 2
        assert (pd.Timestamp('2014-09-30'), 'start') in grouped.groups
        assert (pd.Timestamp('2013-10-31'), 'start') in grouped.groups

        res = grouped.get_group((pd.Timestamp('2014-09-30'), 'start'))
        tm.assert_frame_equal(res, df.iloc[[0, 2], :])
        res = grouped.get_group((pd.Timestamp('2013-10-31'), 'start'))
        tm.assert_frame_equal(res, df.iloc[[1], :])

        # length=3
        df = pd.DataFrame({'event': ['start', 'start', 'start'],
                           'change': [1234, 5678, 9123]},
                          index=pd.DatetimeIndex(['2014-09-10', '2013-10-10',
                                                  '2014-08-05']))
        grouped = df.groupby([pd.Grouper(freq='M'), 'event'])
        assert len(grouped.groups) == 3
        assert grouped.ngroups == 3
        assert (pd.Timestamp('2014-09-30'), 'start') in grouped.groups
        assert (pd.Timestamp('2013-10-31'), 'start') in grouped.groups
        assert (pd.Timestamp('2014-08-31'), 'start') in grouped.groups

        res = grouped.get_group((pd.Timestamp('2014-09-30'), 'start'))
        tm.assert_frame_equal(res, df.iloc[[0], :])
        res = grouped.get_group((pd.Timestamp('2013-10-31'), 'start'))
        tm.assert_frame_equal(res, df.iloc[[1], :])
        res = grouped.get_group((pd.Timestamp('2014-08-31'), 'start'))
        tm.assert_frame_equal(res, df.iloc[[2], :])

    def test_grouping_string_repr(self):
        # GH 13394
        mi = MultiIndex.from_arrays([list("AAB"), list("aba")])
        df = DataFrame([[1, 2, 3]], columns=mi)
        gr = df.groupby(df[('A', 'a')])

        result = gr.grouper.groupings[0].__repr__()
        expected = "Grouping(('A', 'a'))"
        assert result == expected