test_axis_select_reindex.py

from datetime import datetime
import re

import numpy as np
import pytest

from pandas.errors import PerformanceWarning

import pandas as pd
from pandas import Categorical, DataFrame, Index, MultiIndex, Series, date_range, isna
import pandas.util.testing as tm
from pandas.util.testing import assert_frame_equal


class TestDataFrameSelectReindex:
    # These are specific reindex-based tests; other indexing tests should go in
    # test_indexing

    def test_drop_names(self):
        df = DataFrame(
            [[1, 2, 3], [3, 4, 5], [5, 6, 7]],
            index=["a", "b", "c"],
            columns=["d", "e", "f"],
        )
        df.index.name, df.columns.name = "first", "second"
        df_dropped_b = df.drop("b")
        df_dropped_e = df.drop("e", axis=1)
        df_inplace_b, df_inplace_e = df.copy(), df.copy()
        df_inplace_b.drop("b", inplace=True)
        df_inplace_e.drop("e", axis=1, inplace=True)
        for obj in (df_dropped_b, df_dropped_e, df_inplace_b, df_inplace_e):
            assert obj.index.name == "first"
            assert obj.columns.name == "second"
        assert list(df.columns) == ["d", "e", "f"]

        msg = r"\['g'\] not found in axis"
        with pytest.raises(KeyError, match=msg):
            df.drop(["g"])
        with pytest.raises(KeyError, match=msg):
            df.drop(["g"], 1)

        # errors = 'ignore'
        dropped = df.drop(["g"], errors="ignore")
        expected = Index(["a", "b", "c"], name="first")
        tm.assert_index_equal(dropped.index, expected)

        dropped = df.drop(["b", "g"], errors="ignore")
        expected = Index(["a", "c"], name="first")
        tm.assert_index_equal(dropped.index, expected)

        dropped = df.drop(["g"], axis=1, errors="ignore")
        expected = Index(["d", "e", "f"], name="second")
        tm.assert_index_equal(dropped.columns, expected)

        dropped = df.drop(["d", "g"], axis=1, errors="ignore")
        expected = Index(["e", "f"], name="second")
        tm.assert_index_equal(dropped.columns, expected)

        # GH 16398
        dropped = df.drop([], errors="ignore")
        expected = Index(["a", "b", "c"], name="first")
        tm.assert_index_equal(dropped.index, expected)

    def test_drop_col_still_multiindex(self):
        arrays = [["a", "b", "c", "top"], ["", "", "", "OD"], ["", "", "", "wx"]]

        tuples = sorted(zip(*arrays))
        index = MultiIndex.from_tuples(tuples)

        df = DataFrame(np.random.randn(3, 4), columns=index)
        del df[("a", "", "")]
        assert isinstance(df.columns, MultiIndex)

    def test_drop(self):
        simple = DataFrame({"A": [1, 2, 3, 4], "B": [0, 1, 2, 3]})
        assert_frame_equal(simple.drop("A", axis=1), simple[["B"]])
        assert_frame_equal(simple.drop(["A", "B"], axis="columns"), simple[[]])
        assert_frame_equal(simple.drop([0, 1, 3], axis=0), simple.loc[[2], :])
        assert_frame_equal(simple.drop([0, 3], axis="index"), simple.loc[[1, 2], :])

        with pytest.raises(KeyError, match=r"\[5\] not found in axis"):
            simple.drop(5)
        with pytest.raises(KeyError, match=r"\['C'\] not found in axis"):
            simple.drop("C", 1)
        with pytest.raises(KeyError, match=r"\[5\] not found in axis"):
            simple.drop([1, 5])
        with pytest.raises(KeyError, match=r"\['C'\] not found in axis"):
            simple.drop(["A", "C"], 1)

        # errors = 'ignore'
        assert_frame_equal(simple.drop(5, errors="ignore"), simple)
        assert_frame_equal(
            simple.drop([0, 5], errors="ignore"), simple.loc[[1, 2, 3], :]
        )
        assert_frame_equal(simple.drop("C", axis=1, errors="ignore"), simple)
        assert_frame_equal(
            simple.drop(["A", "C"], axis=1, errors="ignore"), simple[["B"]]
        )

        # non-unique - wheee!
        nu_df = DataFrame(
            list(zip(range(3), range(-3, 1), list("abc"))), columns=["a", "a", "b"]
        )
        assert_frame_equal(nu_df.drop("a", axis=1), nu_df[["b"]])
        assert_frame_equal(nu_df.drop("b", axis="columns"), nu_df["a"])
        assert_frame_equal(nu_df.drop([]), nu_df)  # GH 16398

        nu_df = nu_df.set_index(pd.Index(["X", "Y", "X"]))
        nu_df.columns = list("abc")
        assert_frame_equal(nu_df.drop("X", axis="rows"), nu_df.loc[["Y"], :])
        assert_frame_equal(nu_df.drop(["X", "Y"], axis=0), nu_df.loc[[], :])

        # inplace cache issue
        # GH 5628
        df = pd.DataFrame(np.random.randn(10, 3), columns=list("abc"))
        expected = df[~(df.b > 0)]
        df.drop(labels=df[df.b > 0].index, inplace=True)
        assert_frame_equal(df, expected)

        # Empty DatetimeIndex/list, GH 27994
        df_index = pd.DataFrame(
            {"a": [0, 1]},
            index=[pd.Timestamp("2019-01-01"), pd.Timestamp("2019-01-01")],
        )
        assert_frame_equal(df_index.drop([]), df_index)
        assert_frame_equal(df_index.drop(df_index[df_index["a"] > 2].index), df_index)

    def test_drop_multiindex_not_lexsorted(self):
        # GH 11640

        # define the lexsorted version
        lexsorted_mi = MultiIndex.from_tuples(
            [("a", ""), ("b1", "c1"), ("b2", "c2")], names=["b", "c"]
        )
        lexsorted_df = DataFrame([[1, 3, 4]], columns=lexsorted_mi)
        assert lexsorted_df.columns.is_lexsorted()

        # define the non-lexsorted version
        not_lexsorted_df = DataFrame(
            columns=["a", "b", "c", "d"], data=[[1, "b1", "c1", 3], [1, "b2", "c2", 4]]
        )
        not_lexsorted_df = not_lexsorted_df.pivot_table(
            index="a", columns=["b", "c"], values="d"
        )
        not_lexsorted_df = not_lexsorted_df.reset_index()
        assert not not_lexsorted_df.columns.is_lexsorted()

        # compare the results
        tm.assert_frame_equal(lexsorted_df, not_lexsorted_df)

        expected = lexsorted_df.drop("a", axis=1)
        with tm.assert_produces_warning(PerformanceWarning):
            result = not_lexsorted_df.drop("a", axis=1)

        tm.assert_frame_equal(result, expected)

    def test_drop_api_equivalence(self):
        # equivalence of the labels/axis and index/columns API's (GH12392)
        df = DataFrame(
            [[1, 2, 3], [3, 4, 5], [5, 6, 7]],
            index=["a", "b", "c"],
            columns=["d", "e", "f"],
        )

        res1 = df.drop("a")
        res2 = df.drop(index="a")
        tm.assert_frame_equal(res1, res2)

        res1 = df.drop("d", 1)
        res2 = df.drop(columns="d")
        tm.assert_frame_equal(res1, res2)

        res1 = df.drop(labels="e", axis=1)
        res2 = df.drop(columns="e")
        tm.assert_frame_equal(res1, res2)

        res1 = df.drop(["a"], axis=0)
        res2 = df.drop(index=["a"])
        tm.assert_frame_equal(res1, res2)

        res1 = df.drop(["a"], axis=0).drop(["d"], axis=1)
        res2 = df.drop(index=["a"], columns=["d"])
        tm.assert_frame_equal(res1, res2)

        with pytest.raises(ValueError):
            df.drop(labels="a", index="b")

        with pytest.raises(ValueError):
            df.drop(labels="a", columns="b")

        with pytest.raises(ValueError):
            df.drop(axis=1)

    def test_merge_join_different_levels(self):
        # GH 9455

        # first dataframe
        df1 = DataFrame(columns=["a", "b"], data=[[1, 11], [0, 22]])

        # second dataframe
        columns = MultiIndex.from_tuples([("a", ""), ("c", "c1")])
        df2 = DataFrame(columns=columns, data=[[1, 33], [0, 44]])

        # merge
        columns = ["a", "b", ("c", "c1")]
        expected = DataFrame(columns=columns, data=[[1, 11, 33], [0, 22, 44]])
        with tm.assert_produces_warning(UserWarning):
            result = pd.merge(df1, df2, on="a")
        tm.assert_frame_equal(result, expected)

        # join, see discussion in GH 12219
        columns = ["a", "b", ("a", ""), ("c", "c1")]
        expected = DataFrame(columns=columns, data=[[1, 11, 0, 44], [0, 22, 1, 33]])
        with tm.assert_produces_warning(UserWarning):
            result = df1.join(df2, on="a")
        tm.assert_frame_equal(result, expected)

    def test_reindex(self, float_frame):
        datetime_series = tm.makeTimeSeries(nper=30)

        newFrame = float_frame.reindex(datetime_series.index)

        for col in newFrame.columns:
            for idx, val in newFrame[col].items():
                if idx in float_frame.index:
                    if np.isnan(val):
                        assert np.isnan(float_frame[col][idx])
                    else:
                        assert val == float_frame[col][idx]
                else:
                    assert np.isnan(val)

        for col, series in newFrame.items():
            assert tm.equalContents(series.index, newFrame.index)
        emptyFrame = float_frame.reindex(Index([]))
        assert len(emptyFrame.index) == 0

        # Cython code should be unit-tested directly
        nonContigFrame = float_frame.reindex(datetime_series.index[::2])

        for col in nonContigFrame.columns:
            for idx, val in nonContigFrame[col].items():
                if idx in float_frame.index:
                    if np.isnan(val):
                        assert np.isnan(float_frame[col][idx])
                    else:
                        assert val == float_frame[col][idx]
                else:
                    assert np.isnan(val)

        for col, series in nonContigFrame.items():
            assert tm.equalContents(series.index, nonContigFrame.index)

        # corner cases

        # Same index, copies values but not index if copy=False
        newFrame = float_frame.reindex(float_frame.index, copy=False)
        assert newFrame.index is float_frame.index

        # length zero
        newFrame = float_frame.reindex([])
        assert newFrame.empty
        assert len(newFrame.columns) == len(float_frame.columns)

        # length zero with columns reindexed with non-empty index
        newFrame = float_frame.reindex([])
        newFrame = newFrame.reindex(float_frame.index)
        assert len(newFrame.index) == len(float_frame.index)
        assert len(newFrame.columns) == len(float_frame.columns)

        # pass non-Index
        newFrame = float_frame.reindex(list(datetime_series.index))
        tm.assert_index_equal(newFrame.index, datetime_series.index)

        # copy with no axes
        result = float_frame.reindex()
        assert_frame_equal(result, float_frame)
        assert result is not float_frame

    def test_reindex_nan(self):
        df = pd.DataFrame(
            [[1, 2], [3, 5], [7, 11], [9, 23]],
            index=[2, np.nan, 1, 5],
            columns=["joe", "jim"],
        )

        i, j = [np.nan, 5, 5, np.nan, 1, 2, np.nan], [1, 3, 3, 1, 2, 0, 1]
        assert_frame_equal(df.reindex(i), df.iloc[j])

        df.index = df.index.astype("object")
        assert_frame_equal(df.reindex(i), df.iloc[j], check_index_type=False)

        # GH10388
        df = pd.DataFrame(
            {
                "other": ["a", "b", np.nan, "c"],
                "date": ["2015-03-22", np.nan, "2012-01-08", np.nan],
                "amount": [2, 3, 4, 5],
            }
        )

        df["date"] = pd.to_datetime(df.date)
        df["delta"] = (pd.to_datetime("2015-06-18") - df["date"]).shift(1)

        left = df.set_index(["delta", "other", "date"]).reset_index()
        right = df.reindex(columns=["delta", "other", "date", "amount"])
        assert_frame_equal(left, right)

    def test_reindex_name_remains(self):
        s = Series(np.random.rand(10))
        df = DataFrame(s, index=np.arange(len(s)))
        i = Series(np.arange(10), name="iname")

        df = df.reindex(i)
        assert df.index.name == "iname"

        df = df.reindex(Index(np.arange(10), name="tmpname"))
        assert df.index.name == "tmpname"

        s = Series(np.random.rand(10))
        df = DataFrame(s.T, index=np.arange(len(s)))
        i = Series(np.arange(10), name="iname")
        df = df.reindex(columns=i)
        assert df.columns.name == "iname"

    def test_reindex_int(self, int_frame):
        smaller = int_frame.reindex(int_frame.index[::2])

        assert smaller["A"].dtype == np.int64

        bigger = smaller.reindex(int_frame.index)
        assert bigger["A"].dtype == np.float64

        smaller = int_frame.reindex(columns=["A", "B"])
        assert smaller["A"].dtype == np.int64

    def test_reindex_like(self, float_frame):
        other = float_frame.reindex(index=float_frame.index[:10], columns=["C", "B"])

        assert_frame_equal(other, float_frame.reindex_like(other))

    def test_reindex_columns(self, float_frame):
        new_frame = float_frame.reindex(columns=["A", "B", "E"])

        tm.assert_series_equal(new_frame["B"], float_frame["B"])
        assert np.isnan(new_frame["E"]).all()
        assert "C" not in new_frame

        # Length zero
        new_frame = float_frame.reindex(columns=[])
        assert new_frame.empty

    def test_reindex_columns_method(self):

        # GH 14992, reindexing over columns ignored method
        df = DataFrame(
            data=[[11, 12, 13], [21, 22, 23], [31, 32, 33]],
            index=[1, 2, 4],
            columns=[1, 2, 4],
            dtype=float,
        )

        # default method
        result = df.reindex(columns=range(6))
        expected = DataFrame(
            data=[
                [np.nan, 11, 12, np.nan, 13, np.nan],
                [np.nan, 21, 22, np.nan, 23, np.nan],
                [np.nan, 31, 32, np.nan, 33, np.nan],
            ],
            index=[1, 2, 4],
            columns=range(6),
            dtype=float,
        )
        assert_frame_equal(result, expected)

        # method='ffill'
        result = df.reindex(columns=range(6), method="ffill")
        expected = DataFrame(
            data=[
                [np.nan, 11, 12, 12, 13, 13],
                [np.nan, 21, 22, 22, 23, 23],
                [np.nan, 31, 32, 32, 33, 33],
            ],
            index=[1, 2, 4],
            columns=range(6),
            dtype=float,
        )
        assert_frame_equal(result, expected)

        # method='bfill'
        result = df.reindex(columns=range(6), method="bfill")
        expected = DataFrame(
            data=[
                [11, 11, 12, 13, 13, np.nan],
                [21, 21, 22, 23, 23, np.nan],
                [31, 31, 32, 33, 33, np.nan],
            ],
            index=[1, 2, 4],
            columns=range(6),
            dtype=float,
        )
        assert_frame_equal(result, expected)

    def test_reindex_axes(self):
        # GH 3317, reindexing by both axes loses freq of the index
        df = DataFrame(
            np.ones((3, 3)),
            index=[datetime(2012, 1, 1), datetime(2012, 1, 2), datetime(2012, 1, 3)],
            columns=["a", "b", "c"],
        )
        time_freq = date_range("2012-01-01", "2012-01-03", freq="d")
        some_cols = ["a", "b"]

        index_freq = df.reindex(index=time_freq).index.freq
        both_freq = df.reindex(index=time_freq, columns=some_cols).index.freq
        seq_freq = df.reindex(index=time_freq).reindex(columns=some_cols).index.freq
        assert index_freq == both_freq
        assert index_freq == seq_freq

    def test_reindex_fill_value(self):
        df = DataFrame(np.random.randn(10, 4))

        # axis=0
        result = df.reindex(list(range(15)))
        assert np.isnan(result.values[-5:]).all()

        result = df.reindex(range(15), fill_value=0)
        expected = df.reindex(range(15)).fillna(0)
        assert_frame_equal(result, expected)

        # axis=1
        result = df.reindex(columns=range(5), fill_value=0.0)
        expected = df.copy()
        expected[4] = 0.0
        assert_frame_equal(result, expected)

        result = df.reindex(columns=range(5), fill_value=0)
        expected = df.copy()
        expected[4] = 0
        assert_frame_equal(result, expected)

        result = df.reindex(columns=range(5), fill_value="foo")
        expected = df.copy()
        expected[4] = "foo"
        assert_frame_equal(result, expected)

        # other dtypes
        df["foo"] = "foo"
        result = df.reindex(range(15), fill_value=0)
        expected = df.reindex(range(15)).fillna(0)
        assert_frame_equal(result, expected)

    def test_reindex_dups(self):

        # GH4746, reindex on duplicate index error messages
        arr = np.random.randn(10)
        df = DataFrame(arr, index=[1, 2, 3, 4, 5, 1, 2, 3, 4, 5])

        # set index is ok
        result = df.copy()
        result.index = list(range(len(df)))
        expected = DataFrame(arr, index=list(range(len(df))))
        assert_frame_equal(result, expected)

        # reindex fails
        msg = "cannot reindex from a duplicate axis"
        with pytest.raises(ValueError, match=msg):
            df.reindex(index=list(range(len(df))))

    def test_reindex_axis_style(self):
        # https://github.com/pandas-dev/pandas/issues/12392
        df = pd.DataFrame({"A": [1, 2, 3], "B": [4, 5, 6]})
        expected = pd.DataFrame(
            {"A": [1, 2, np.nan], "B": [4, 5, np.nan]}, index=[0, 1, 3]
        )
        result = df.reindex([0, 1, 3])
        assert_frame_equal(result, expected)

        result = df.reindex([0, 1, 3], axis=0)
        assert_frame_equal(result, expected)

        result = df.reindex([0, 1, 3], axis="index")
        assert_frame_equal(result, expected)

    def test_reindex_positional_warns(self):
        # https://github.com/pandas-dev/pandas/issues/12392
        df = pd.DataFrame({"A": [1, 2, 3], "B": [4, 5, 6]})
        expected = pd.DataFrame({"A": [1.0, 2], "B": [4.0, 5], "C": [np.nan, np.nan]})
        with tm.assert_produces_warning(FutureWarning):
            result = df.reindex([0, 1], ["A", "B", "C"])

        assert_frame_equal(result, expected)

    def test_reindex_axis_style_raises(self):
        # https://github.com/pandas-dev/pandas/issues/12392
        df = pd.DataFrame({"A": [1, 2, 3], "B": [4, 5, 6]})
        with pytest.raises(TypeError, match="Cannot specify both 'axis'"):
            df.reindex([0, 1], ["A"], axis=1)

        with pytest.raises(TypeError, match="Cannot specify both 'axis'"):
            df.reindex([0, 1], ["A"], axis="index")

        with pytest.raises(TypeError, match="Cannot specify both 'axis'"):
            df.reindex(index=[0, 1], axis="index")

        with pytest.raises(TypeError, match="Cannot specify both 'axis'"):
            df.reindex(index=[0, 1], axis="columns")

        with pytest.raises(TypeError, match="Cannot specify both 'axis'"):
            df.reindex(columns=[0, 1], axis="columns")

        with pytest.raises(TypeError, match="Cannot specify both 'axis'"):
            df.reindex(index=[0, 1], columns=[0, 1], axis="columns")

        with pytest.raises(TypeError, match="Cannot specify all"):
            df.reindex([0, 1], [0], ["A"])

        # Mixing styles
        with pytest.raises(TypeError, match="Cannot specify both 'axis'"):
            df.reindex(index=[0, 1], axis="index")

        with pytest.raises(TypeError, match="Cannot specify both 'axis'"):
            df.reindex(index=[0, 1], axis="columns")

        # Duplicates
        with pytest.raises(TypeError, match="multiple values"):
            df.reindex([0, 1], labels=[0, 1])

    def test_reindex_single_named_indexer(self):
        # https://github.com/pandas-dev/pandas/issues/12392
        df = pd.DataFrame({"A": [1, 2, 3], "B": [1, 2, 3]})
        result = df.reindex([0, 1], columns=["A"])
        expected = pd.DataFrame({"A": [1, 2]})
        assert_frame_equal(result, expected)

    def test_reindex_api_equivalence(self):
        # https://github.com/pandas-dev/pandas/issues/12392
        # equivalence of the labels/axis and index/columns API's
        df = DataFrame(
            [[1, 2, 3], [3, 4, 5], [5, 6, 7]],
            index=["a", "b", "c"],
            columns=["d", "e", "f"],
        )

        res1 = df.reindex(["b", "a"])
        res2 = df.reindex(index=["b", "a"])
        res3 = df.reindex(labels=["b", "a"])
        res4 = df.reindex(labels=["b", "a"], axis=0)
        res5 = df.reindex(["b", "a"], axis=0)
        for res in [res2, res3, res4, res5]:
            tm.assert_frame_equal(res1, res)

        res1 = df.reindex(columns=["e", "d"])
        res2 = df.reindex(["e", "d"], axis=1)
        res3 = df.reindex(labels=["e", "d"], axis=1)
        for res in [res2, res3]:
            tm.assert_frame_equal(res1, res)

        with tm.assert_produces_warning(FutureWarning) as m:
            res1 = df.reindex(["b", "a"], ["e", "d"])
        assert "reindex" in str(m[0].message)
        res2 = df.reindex(columns=["e", "d"], index=["b", "a"])
        res3 = df.reindex(labels=["b", "a"], axis=0).reindex(labels=["e", "d"], axis=1)
        for res in [res2, res3]:
            tm.assert_frame_equal(res1, res)

    def test_align_float(self, float_frame):
        af, bf = float_frame.align(float_frame)
        assert af._data is not float_frame._data

        af, bf = float_frame.align(float_frame, copy=False)
        assert af._data is float_frame._data

        # axis = 0
        other = float_frame.iloc[:-5, :3]
        af, bf = float_frame.align(other, axis=0, fill_value=-1)

        tm.assert_index_equal(bf.columns, other.columns)

        # test fill value
        join_idx = float_frame.index.join(other.index)
        diff_a = float_frame.index.difference(join_idx)
        diff_b = other.index.difference(join_idx)
        diff_a_vals = af.reindex(diff_a).values
        diff_b_vals = bf.reindex(diff_b).values
        assert (diff_a_vals == -1).all()

        af, bf = float_frame.align(other, join="right", axis=0)
        tm.assert_index_equal(bf.columns, other.columns)
        tm.assert_index_equal(bf.index, other.index)
        tm.assert_index_equal(af.index, other.index)

        # axis = 1
        other = float_frame.iloc[:-5, :3].copy()
        af, bf = float_frame.align(other, axis=1)
        tm.assert_index_equal(bf.columns, float_frame.columns)
        tm.assert_index_equal(bf.index, other.index)

        # test fill value
        join_idx = float_frame.index.join(other.index)
        diff_a = float_frame.index.difference(join_idx)
        diff_b = other.index.difference(join_idx)
        diff_a_vals = af.reindex(diff_a).values

        # TODO(wesm): unused?
        diff_b_vals = bf.reindex(diff_b).values  # noqa

        assert (diff_a_vals == -1).all()

        af, bf = float_frame.align(other, join="inner", axis=1)
        tm.assert_index_equal(bf.columns, other.columns)

        af, bf = float_frame.align(other, join="inner", axis=1, method="pad")
        tm.assert_index_equal(bf.columns, other.columns)

        af, bf = float_frame.align(
            other.iloc[:, 0], join="inner", axis=1, method=None, fill_value=None
        )
        tm.assert_index_equal(bf.index, Index([]))

        af, bf = float_frame.align(
            other.iloc[:, 0], join="inner", axis=1, method=None, fill_value=0
        )
        tm.assert_index_equal(bf.index, Index([]))

        # Try to align DataFrame to Series along bad axis
        with pytest.raises(ValueError):
            float_frame.align(af.iloc[0, :3], join="inner", axis=2)

        # align dataframe to series with broadcast or not
        idx = float_frame.index
        s = Series(range(len(idx)), index=idx)

        left, right = float_frame.align(s, axis=0)
        tm.assert_index_equal(left.index, float_frame.index)
        tm.assert_index_equal(right.index, float_frame.index)
        assert isinstance(right, Series)

        left, right = float_frame.align(s, broadcast_axis=1)
        tm.assert_index_equal(left.index, float_frame.index)
        expected = {c: s for c in float_frame.columns}
        expected = DataFrame(
            expected, index=float_frame.index, columns=float_frame.columns
        )
        tm.assert_frame_equal(right, expected)

        # see gh-9558
        df = DataFrame({"a": [1, 2, 3], "b": [4, 5, 6]})
        result = df[df["a"] == 2]
        expected = DataFrame([[2, 5]], index=[1], columns=["a", "b"])
        tm.assert_frame_equal(result, expected)

        result = df.where(df["a"] == 2, 0)
        expected = DataFrame({"a": [0, 2, 0], "b": [0, 5, 0]})
        tm.assert_frame_equal(result, expected)

    def test_align_int(self, int_frame):
        # test other non-float types
        other = DataFrame(index=range(5), columns=["A", "B", "C"])

        af, bf = int_frame.align(other, join="inner", axis=1, method="pad")
        tm.assert_index_equal(bf.columns, other.columns)

    def test_align_mixed_type(self, float_string_frame):

        af, bf = float_string_frame.align(
            float_string_frame, join="inner", axis=1, method="pad"
        )
        tm.assert_index_equal(bf.columns, float_string_frame.columns)

    def test_align_mixed_float(self, mixed_float_frame):
        # mixed floats/ints
        other = DataFrame(index=range(5), columns=["A", "B", "C"])

        af, bf = mixed_float_frame.align(
            other.iloc[:, 0], join="inner", axis=1, method=None, fill_value=0
        )
        tm.assert_index_equal(bf.index, Index([]))

    def test_align_mixed_int(self, mixed_int_frame):
        other = DataFrame(index=range(5), columns=["A", "B", "C"])

        af, bf = mixed_int_frame.align(
            other.iloc[:, 0], join="inner", axis=1, method=None, fill_value=0
        )
        tm.assert_index_equal(bf.index, Index([]))

    def _check_align(self, a, b, axis, fill_axis, how, method, limit=None):
        aa, ab = a.align(
            b, axis=axis, join=how, method=method, limit=limit, fill_axis=fill_axis
        )

        join_index, join_columns = None, None

        ea, eb = a, b
        if axis is None or axis == 0:
            join_index = a.index.join(b.index, how=how)
            ea = ea.reindex(index=join_index)
            eb = eb.reindex(index=join_index)

        if axis is None or axis == 1:
            join_columns = a.columns.join(b.columns, how=how)
            ea = ea.reindex(columns=join_columns)
            eb = eb.reindex(columns=join_columns)

        ea = ea.fillna(axis=fill_axis, method=method, limit=limit)
        eb = eb.fillna(axis=fill_axis, method=method, limit=limit)

        assert_frame_equal(aa, ea)
        assert_frame_equal(ab, eb)

    @pytest.mark.parametrize("meth", ["pad", "bfill"])
    @pytest.mark.parametrize("ax", [0, 1, None])
    @pytest.mark.parametrize("fax", [0, 1])
    @pytest.mark.parametrize("how", ["inner", "outer", "left", "right"])
    def test_align_fill_method(self, how, meth, ax, fax, float_frame):
        df = float_frame
        self._check_align_fill(df, how, meth, ax, fax)

    def _check_align_fill(self, frame, kind, meth, ax, fax):
        left = frame.iloc[0:4, :10]
        right = frame.iloc[2:, 6:]
        empty = frame.iloc[:0, :0]

        self._check_align(left, right, axis=ax, fill_axis=fax, how=kind, method=meth)
        self._check_align(
            left, right, axis=ax, fill_axis=fax, how=kind, method=meth, limit=1
        )

        # empty left
        self._check_align(empty, right, axis=ax, fill_axis=fax, how=kind, method=meth)
        self._check_align(
            empty, right, axis=ax, fill_axis=fax, how=kind, method=meth, limit=1
        )

        # empty right
        self._check_align(left, empty, axis=ax, fill_axis=fax, how=kind, method=meth)
        self._check_align(
            left, empty, axis=ax, fill_axis=fax, how=kind, method=meth, limit=1
        )

        # both empty
        self._check_align(empty, empty, axis=ax, fill_axis=fax, how=kind, method=meth)
        self._check_align(
            empty, empty, axis=ax, fill_axis=fax, how=kind, method=meth, limit=1
        )

    def test_align_int_fill_bug(self):
        # GH #910
        X = np.arange(10 * 10, dtype="float64").reshape(10, 10)
        Y = np.ones((10, 1), dtype=int)

        df1 = DataFrame(X)
        df1["0.X"] = Y.squeeze()

        df2 = df1.astype(float)

        result = df1 - df1.mean()
        expected = df2 - df2.mean()
        assert_frame_equal(result, expected)

    def test_align_multiindex(self):
        # GH 10665
        # same test cases as test_align_multiindex in test_series.py

        midx = pd.MultiIndex.from_product(
            [range(2), range(3), range(2)], names=("a", "b", "c")
        )
        idx = pd.Index(range(2), name="b")
        df1 = pd.DataFrame(np.arange(12, dtype="int64"), index=midx)
        df2 = pd.DataFrame(np.arange(2, dtype="int64"), index=idx)

        # these must be the same results (but flipped)
        res1l, res1r = df1.align(df2, join="left")
        res2l, res2r = df2.align(df1, join="right")

        expl = df1
        assert_frame_equal(expl, res1l)
        assert_frame_equal(expl, res2r)
        expr = pd.DataFrame([0, 0, 1, 1, np.nan, np.nan] * 2, index=midx)
        assert_frame_equal(expr, res1r)
        assert_frame_equal(expr, res2l)

        res1l, res1r = df1.align(df2, join="right")
        res2l, res2r = df2.align(df1, join="left")

        exp_idx = pd.MultiIndex.from_product(
            [range(2), range(2), range(2)], names=("a", "b", "c")
        )
        expl = pd.DataFrame([0, 1, 2, 3, 6, 7, 8, 9], index=exp_idx)
        assert_frame_equal(expl, res1l)
        assert_frame_equal(expl, res2r)
        expr = pd.DataFrame([0, 0, 1, 1] * 2, index=exp_idx)
        assert_frame_equal(expr, res1r)
        assert_frame_equal(expr, res2l)

    def test_align_series_combinations(self):
        df = pd.DataFrame({"a": [1, 3, 5], "b": [1, 3, 5]}, index=list("ACE"))
        s = pd.Series([1, 2, 4], index=list("ABD"), name="x")

        # frame + series
        res1, res2 = df.align(s, axis=0)
        exp1 = pd.DataFrame(
            {"a": [1, np.nan, 3, np.nan, 5], "b": [1, np.nan, 3, np.nan, 5]},
            index=list("ABCDE"),
        )
        exp2 = pd.Series([1, 2, np.nan, 4, np.nan], index=list("ABCDE"), name="x")

        tm.assert_frame_equal(res1, exp1)
        tm.assert_series_equal(res2, exp2)

        # series + frame
        res1, res2 = s.align(df)
        tm.assert_series_equal(res1, exp2)
        tm.assert_frame_equal(res2, exp1)

    def test_filter(self, float_frame, float_string_frame):
        # Items
        filtered = float_frame.filter(["A", "B", "E"])
        assert len(filtered.columns) == 2
        assert "E" not in filtered

        filtered = float_frame.filter(["A", "B", "E"], axis="columns")
        assert len(filtered.columns) == 2
        assert "E" not in filtered

        # Other axis
        idx = float_frame.index[0:4]
        filtered = float_frame.filter(idx, axis="index")
        expected = float_frame.reindex(index=idx)
        tm.assert_frame_equal(filtered, expected)

        # like
        fcopy = float_frame.copy()
        fcopy["AA"] = 1

        filtered = fcopy.filter(like="A")
        assert len(filtered.columns) == 2
        assert "AA" in filtered

        # like with ints in column names
        df = DataFrame(0.0, index=[0, 1, 2], columns=[0, 1, "_A", "_B"])
        filtered = df.filter(like="_")
        assert len(filtered.columns) == 2

        # regex with ints in column names
        # from PR #10384
        df = DataFrame(0.0, index=[0, 1, 2], columns=["A1", 1, "B", 2, "C"])
        expected = DataFrame(
            0.0, index=[0, 1, 2], columns=pd.Index([1, 2], dtype=object)
        )
        filtered = df.filter(regex="^[0-9]+$")
        tm.assert_frame_equal(filtered, expected)

        expected = DataFrame(0.0, index=[0, 1, 2], columns=[0, "0", 1, "1"])
        # shouldn't remove anything
        filtered = expected.filter(regex="^[0-9]+$")
        tm.assert_frame_equal(filtered, expected)

        # pass in None
        with pytest.raises(TypeError, match="Must pass"):
            float_frame.filter()
        with pytest.raises(TypeError, match="Must pass"):
            float_frame.filter(items=None)
        with pytest.raises(TypeError, match="Must pass"):
            float_frame.filter(axis=1)

        # test mutually exclusive arguments
        with pytest.raises(TypeError, match="mutually exclusive"):
            float_frame.filter(items=["one", "three"], regex="e$", like="bbi")
        with pytest.raises(TypeError, match="mutually exclusive"):
            float_frame.filter(items=["one", "three"], regex="e$", axis=1)
        with pytest.raises(TypeError, match="mutually exclusive"):
            float_frame.filter(items=["one", "three"], regex="e$")
        with pytest.raises(TypeError, match="mutually exclusive"):
            float_frame.filter(items=["one", "three"], like="bbi", axis=0)
        with pytest.raises(TypeError, match="mutually exclusive"):
            float_frame.filter(items=["one", "three"], like="bbi")

        # objects
        filtered = float_string_frame.filter(like="foo")
        assert "foo" in filtered

        # unicode columns, won't ascii-encode
        df = float_frame.rename(columns={"B": "\u2202"})
        filtered = df.filter(like="C")
        assert "C" in filtered

    def test_filter_regex_search(self, float_frame):
        fcopy = float_frame.copy()
        fcopy["AA"] = 1

        # regex
        filtered = fcopy.filter(regex="[A]+")
        assert len(filtered.columns) == 2
        assert "AA" in filtered

        # doesn't have to be at beginning
        df = DataFrame(
            {"aBBa": [1, 2], "BBaBB": [1, 2], "aCCa": [1, 2], "aCCaBB": [1, 2]}
        )

        result = df.filter(regex="BB")
        exp = df[[x for x in df.columns if "BB" in x]]
        assert_frame_equal(result, exp)

    @pytest.mark.parametrize(
        "name,expected",
        [
            ("a", DataFrame({"a": [1, 2]})),
            ("a", DataFrame({"a": [1, 2]})),
            ("あ", DataFrame({"あ": [3, 4]})),
        ],
    )
    def test_filter_unicode(self, name, expected):
        # GH13101
        df = DataFrame({"a": [1, 2], "あ": [3, 4]})

        assert_frame_equal(df.filter(like=name), expected)
        assert_frame_equal(df.filter(regex=name), expected)

    @pytest.mark.parametrize("name", ["a", "a"])
    def test_filter_bytestring(self, name):
        # GH13101
        df = DataFrame({b"a": [1, 2], b"b": [3, 4]})
        expected = DataFrame({b"a": [1, 2]})

        assert_frame_equal(df.filter(like=name), expected)
        assert_frame_equal(df.filter(regex=name), expected)

    def test_filter_corner(self):
        empty = DataFrame()

        result = empty.filter([])
        assert_frame_equal(result, empty)

        result = empty.filter(like="foo")
        assert_frame_equal(result, empty)

    def test_take(self, float_frame):
        # homogeneous
        order = [3, 1, 2, 0]
        for df in [float_frame]:

            result = df.take(order, axis=0)
            expected = df.reindex(df.index.take(order))
            assert_frame_equal(result, expected)

            # axis = 1
            result = df.take(order, axis=1)
            expected = df.loc[:, ["D", "B", "C", "A"]]
            assert_frame_equal(result, expected, check_names=False)

        # negative indices
        order = [2, 1, -1]
        for df in [float_frame]:

            result = df.take(order, axis=0)
            expected = df.reindex(df.index.take(order))
            assert_frame_equal(result, expected)

            result = df.take(order, axis=0)
            assert_frame_equal(result, expected)

            # axis = 1
            result = df.take(order, axis=1)
            expected = df.loc[:, ["C", "B", "D"]]
            assert_frame_equal(result, expected, check_names=False)

        # illegal indices
        msg = "indices are out-of-bounds"
        with pytest.raises(IndexError, match=msg):
            df.take([3, 1, 2, 30], axis=0)
        with pytest.raises(IndexError, match=msg):
            df.take([3, 1, 2, -31], axis=0)
        with pytest.raises(IndexError, match=msg):
            df.take([3, 1, 2, 5], axis=1)
        with pytest.raises(IndexError, match=msg):
            df.take([3, 1, 2, -5], axis=1)

    def test_take_mixed_type(self, float_string_frame):

        # mixed-dtype
        order = [4, 1, 2, 0, 3]
        for df in [float_string_frame]:

            result = df.take(order, axis=0)
            expected = df.reindex(df.index.take(order))
            assert_frame_equal(result, expected)

            # axis = 1
            result = df.take(order, axis=1)
            expected = df.loc[:, ["foo", "B", "C", "A", "D"]]
            assert_frame_equal(result, expected)

        # negative indices
        order = [4, 1, -2]
        for df in [float_string_frame]:

            result = df.take(order, axis=0)
            expected = df.reindex(df.index.take(order))
            assert_frame_equal(result, expected)

            # axis = 1
            result = df.take(order, axis=1)
            expected = df.loc[:, ["foo", "B", "D"]]
            assert_frame_equal(result, expected)

    def test_take_mixed_numeric(self, mixed_float_frame, mixed_int_frame):
        # by dtype
        order = [1, 2, 0, 3]
        for df in [mixed_float_frame, mixed_int_frame]:

            result = df.take(order, axis=0)
            expected = df.reindex(df.index.take(order))
            assert_frame_equal(result, expected)

            # axis = 1
            result = df.take(order, axis=1)
            expected = df.loc[:, ["B", "C", "A", "D"]]
            assert_frame_equal(result, expected)

    def test_reindex_boolean(self):
        frame = DataFrame(
            np.ones((10, 2), dtype=bool), index=np.arange(0, 20, 2), columns=[0, 2]
        )

        reindexed = frame.reindex(np.arange(10))
        assert reindexed.values.dtype == np.object_
        assert isna(reindexed[0][1])

        reindexed = frame.reindex(columns=range(3))
        assert reindexed.values.dtype == np.object_
        assert isna(reindexed[1]).all()

    def test_reindex_objects(self, float_string_frame):
        reindexed = float_string_frame.reindex(columns=["foo", "A", "B"])
        assert "foo" in reindexed

        reindexed = float_string_frame.reindex(columns=["A", "B"])
        assert "foo" not in reindexed

    def test_reindex_corner(self, int_frame):
        index = Index(["a", "b", "c"])
        dm = DataFrame({}).reindex(index=[1, 2, 3])
        reindexed = dm.reindex(columns=index)
        tm.assert_index_equal(reindexed.columns, index)

        # ints are weird
        smaller = int_frame.reindex(columns=["A", "B", "E"])
        assert smaller["E"].dtype == np.float64

    def test_reindex_with_nans(self):
        df = DataFrame(
            [[1, 2], [3, 4], [np.nan, np.nan], [7, 8], [9, 10]],
            columns=["a", "b"],
            index=[100.0, 101.0, np.nan, 102.0, 103.0],
        )

        result = df.reindex(index=[101.0, 102.0, 103.0])
        expected = df.iloc[[1, 3, 4]]
        assert_frame_equal(result, expected)

        result = df.reindex(index=[103.0])
        expected = df.iloc[[4]]
        assert_frame_equal(result, expected)

        result = df.reindex(index=[101.0])
        expected = df.iloc[[1]]
        assert_frame_equal(result, expected)

    def test_reindex_multi(self):
        df = DataFrame(np.random.randn(3, 3))

        result = df.reindex(index=range(4), columns=range(4))
        expected = df.reindex(list(range(4))).reindex(columns=range(4))

        assert_frame_equal(result, expected)

        df = DataFrame(np.random.randint(0, 10, (3, 3)))

        result = df.reindex(index=range(4), columns=range(4))
        expected = df.reindex(list(range(4))).reindex(columns=range(4))

        assert_frame_equal(result, expected)

        df = DataFrame(np.random.randint(0, 10, (3, 3)))

        result = df.reindex(index=range(2), columns=range(2))
        expected = df.reindex(range(2)).reindex(columns=range(2))

        assert_frame_equal(result, expected)

        df = DataFrame(np.random.randn(5, 3) + 1j, columns=["a", "b", "c"])

        result = df.reindex(index=[0, 1], columns=["a", "b"])
        expected = df.reindex([0, 1]).reindex(columns=["a", "b"])

        assert_frame_equal(result, expected)

    def test_reindex_multi_categorical_time(self):
        # https://github.com/pandas-dev/pandas/issues/21390
        midx = pd.MultiIndex.from_product(
            [
                Categorical(["a", "b", "c"]),
                Categorical(date_range("2012-01-01", periods=3, freq="H")),
            ]
        )
        df = pd.DataFrame({"a": range(len(midx))}, index=midx)
        df2 = df.iloc[[0, 1, 2, 3, 4, 5, 6, 8]]

        result = df2.reindex(midx)
        expected = pd.DataFrame({"a": [0, 1, 2, 3, 4, 5, 6, np.nan, 8]}, index=midx)
        assert_frame_equal(result, expected)

    data = [[1, 2, 3], [1, 2, 3]]

    @pytest.mark.parametrize(
        "actual",
        [
            DataFrame(data=data, index=["a", "a"]),
            DataFrame(data=data, index=["a", "b"]),
            DataFrame(data=data, index=["a", "b"]).set_index([0, 1]),
            DataFrame(data=data, index=["a", "a"]).set_index([0, 1]),
        ],
    )
    def test_raise_on_drop_duplicate_index(self, actual):

        # issue 19186
        level = 0 if isinstance(actual.index, MultiIndex) else None
        msg = re.escape("\"['c'] not found in axis\"")
        with pytest.raises(KeyError, match=msg):
            actual.drop("c", level=level, axis=0)
        with pytest.raises(KeyError, match=msg):
            actual.T.drop("c", level=level, axis=1)
        expected_no_err = actual.drop("c", axis=0, level=level, errors="ignore")
        assert_frame_equal(expected_no_err, actual)
        expected_no_err = actual.T.drop("c", axis=1, level=level, errors="ignore")
        assert_frame_equal(expected_no_err.T, actual)

    @pytest.mark.parametrize("index", [[1, 2, 3], [1, 1, 2]])
    @pytest.mark.parametrize("drop_labels", [[], [1], [2]])
    def test_drop_empty_list(self, index, drop_labels):
        # GH 21494
        expected_index = [i for i in index if i not in drop_labels]
        frame = pd.DataFrame(index=index).drop(drop_labels)
        tm.assert_frame_equal(frame, pd.DataFrame(index=expected_index))

    @pytest.mark.parametrize("index", [[1, 2, 3], [1, 2, 2]])
    @pytest.mark.parametrize("drop_labels", [[1, 4], [4, 5]])
    def test_drop_non_empty_list(self, index, drop_labels):
        # GH 21494
        with pytest.raises(KeyError, match="not found in axis"):
            pd.DataFrame(index=index).drop(drop_labels)