from datetime import datetime

import numpy as np
import pytest

import pandas as pd
from pandas import DataFrame, Index, Series, Timestamp, date_range
import pandas.util.testing as tm
from pandas.util.testing import assert_frame_equal, assert_series_equal


class TestDataFrameConcatCommon:
    def test_concat_multiple_frames_dtypes(self):

        # GH 2759
        A = DataFrame(data=np.ones((10, 2)), columns=["foo", "bar"], dtype=np.float64)
        B = DataFrame(data=np.ones((10, 2)), dtype=np.float32)
        results = pd.concat((A, B), axis=1).dtypes
        expected = Series(
            [np.dtype("float64")] * 2 + [np.dtype("float32")] * 2,
            index=["foo", "bar", 0, 1],
        )
        assert_series_equal(results, expected)

    @pytest.mark.parametrize(
        "data",
        [
            pd.date_range("2000", periods=4),
            pd.date_range("2000", periods=4, tz="US/Central"),
            pd.period_range("2000", periods=4),
            pd.timedelta_range(0, periods=4),
        ],
    )
    def test_combine_datetlike_udf(self, data):
        # https://github.com/pandas-dev/pandas/issues/23079
        df = pd.DataFrame({"A": data})
        other = df.copy()
        df.iloc[1, 0] = None

        def combiner(a, b):
            return b

        result = df.combine(other, combiner)
        tm.assert_frame_equal(result, other)

    def test_concat_multiple_tzs(self):
        # GH 12467
        # combining datetime tz-aware and naive DataFrames
        ts1 = Timestamp("2015-01-01", tz=None)
        ts2 = Timestamp("2015-01-01", tz="UTC")
        ts3 = Timestamp("2015-01-01", tz="EST")

        df1 = DataFrame(dict(time=[ts1]))
        df2 = DataFrame(dict(time=[ts2]))
        df3 = DataFrame(dict(time=[ts3]))

        results = pd.concat([df1, df2]).reset_index(drop=True)
        expected = DataFrame(dict(time=[ts1, ts2]), dtype=object)
        assert_frame_equal(results, expected)

        results = pd.concat([df1, df3]).reset_index(drop=True)
        expected = DataFrame(dict(time=[ts1, ts3]), dtype=object)
        assert_frame_equal(results, expected)

        results = pd.concat([df2, df3]).reset_index(drop=True)
        expected = DataFrame(dict(time=[ts2, ts3]))
        assert_frame_equal(results, expected)

    @pytest.mark.parametrize(
        "t1",
        [
            "2015-01-01",
            pytest.param(
                pd.NaT,
                marks=pytest.mark.xfail(
                    reason="GH23037 incorrect dtype when concatenating"
                ),
            ),
        ],
    )
    def test_concat_tz_NaT(self, t1):
        # GH 22796
        # Concating tz-aware multicolumn DataFrames
        ts1 = Timestamp(t1, tz="UTC")
        ts2 = Timestamp("2015-01-01", tz="UTC")
        ts3 = Timestamp("2015-01-01", tz="UTC")

        df1 = DataFrame([[ts1, ts2]])
        df2 = DataFrame([[ts3]])

        result = pd.concat([df1, df2])
        expected = DataFrame([[ts1, ts2], [ts3, pd.NaT]], index=[0, 0])

        assert_frame_equal(result, expected)

    def test_concat_tz_not_aligned(self):
        # GH 22796
        ts = pd.to_datetime([1, 2]).tz_localize("UTC")
        a = pd.DataFrame({"A": ts})
        b = pd.DataFrame({"A": ts, "B": ts})
        result = pd.concat([a, b], sort=True, ignore_index=True)
        expected = pd.DataFrame(
            {"A": list(ts) + list(ts), "B": [pd.NaT, pd.NaT] + list(ts)}
        )
        assert_frame_equal(result, expected)

    def test_concat_tuple_keys(self):
        # GH 14438
        df1 = pd.DataFrame(np.ones((2, 2)), columns=list("AB"))
        df2 = pd.DataFrame(np.ones((3, 2)) * 2, columns=list("AB"))
        results = pd.concat((df1, df2), keys=[("bee", "bah"), ("bee", "boo")])
        expected = pd.DataFrame(
            {
                "A": {
                    ("bee", "bah", 0): 1.0,
                    ("bee", "bah", 1): 1.0,
                    ("bee", "boo", 0): 2.0,
                    ("bee", "boo", 1): 2.0,
                    ("bee", "boo", 2): 2.0,
                },
                "B": {
                    ("bee", "bah", 0): 1.0,
                    ("bee", "bah", 1): 1.0,
                    ("bee", "boo", 0): 2.0,
                    ("bee", "boo", 1): 2.0,
                    ("bee", "boo", 2): 2.0,
                },
            }
        )
        assert_frame_equal(results, expected)

    def test_append_series_dict(self):
        df = DataFrame(np.random.randn(5, 4), columns=["foo", "bar", "baz", "qux"])

        series = df.loc[4]
        msg = "Indexes have overlapping values"
        with pytest.raises(ValueError, match=msg):
            df.append(series, verify_integrity=True)

        series.name = None
        msg = "Can only append a Series if ignore_index=True"
        with pytest.raises(TypeError, match=msg):
            df.append(series, verify_integrity=True)

        result = df.append(series[::-1], ignore_index=True)
        expected = df.append(
            DataFrame({0: series[::-1]}, index=df.columns).T, ignore_index=True
        )
        assert_frame_equal(result, expected)

        # dict
        result = df.append(series.to_dict(), ignore_index=True)
        assert_frame_equal(result, expected)

        result = df.append(series[::-1][:3], ignore_index=True)
        expected = df.append(
            DataFrame({0: series[::-1][:3]}).T, ignore_index=True, sort=True
        )
        assert_frame_equal(result, expected.loc[:, result.columns])

        # can append when name set
        row = df.loc[4]
        row.name = 5
        result = df.append(row)
        expected = df.append(df[-1:], ignore_index=True)
        assert_frame_equal(result, expected)

    def test_append_list_of_series_dicts(self):
        df = DataFrame(np.random.randn(5, 4), columns=["foo", "bar", "baz", "qux"])

        dicts = [x.to_dict() for idx, x in df.iterrows()]

        result = df.append(dicts, ignore_index=True)
        expected = df.append(df, ignore_index=True)
        assert_frame_equal(result, expected)

        # different columns
        dicts = [
            {"foo": 1, "bar": 2, "baz": 3, "peekaboo": 4},
            {"foo": 5, "bar": 6, "baz": 7, "peekaboo": 8},
        ]
        result = df.append(dicts, ignore_index=True, sort=True)
        expected = df.append(DataFrame(dicts), ignore_index=True, sort=True)
        assert_frame_equal(result, expected)

    def test_append_missing_cols(self):
        # GH22252
        # exercise the conditional branch in append method where the data
        # to be appended is a list and does not contain all columns that are in
        # the target DataFrame
        df = DataFrame(np.random.randn(5, 4), columns=["foo", "bar", "baz", "qux"])

        dicts = [{"foo": 9}, {"bar": 10}]
        with tm.assert_produces_warning(None):
            result = df.append(dicts, ignore_index=True, sort=True)

        expected = df.append(DataFrame(dicts), ignore_index=True, sort=True)
        assert_frame_equal(result, expected)

    def test_append_empty_dataframe(self):

        # Empty df append empty df
        df1 = DataFrame()
        df2 = DataFrame()
        result = df1.append(df2)
        expected = df1.copy()
        assert_frame_equal(result, expected)

        # Non-empty df append empty df
        df1 = DataFrame(np.random.randn(5, 2))
        df2 = DataFrame()
        result = df1.append(df2)
        expected = df1.copy()
        assert_frame_equal(result, expected)

        # Empty df with columns append empty df
        df1 = DataFrame(columns=["bar", "foo"])
        df2 = DataFrame()
        result = df1.append(df2)
        expected = df1.copy()
        assert_frame_equal(result, expected)

        # Non-Empty df with columns append empty df
        df1 = DataFrame(np.random.randn(5, 2), columns=["bar", "foo"])
        df2 = DataFrame()
        result = df1.append(df2)
        expected = df1.copy()
        assert_frame_equal(result, expected)

    def test_append_dtypes(self):

        # GH 5754
        # row appends of different dtypes (so need to do by-item)
        # can sometimes infer the correct type

        df1 = DataFrame({"bar": Timestamp("20130101")}, index=range(5))
        df2 = DataFrame()
        result = df1.append(df2)
        expected = df1.copy()
        assert_frame_equal(result, expected)

        df1 = DataFrame({"bar": Timestamp("20130101")}, index=range(1))
        df2 = DataFrame({"bar": "foo"}, index=range(1, 2))
        result = df1.append(df2)
        expected = DataFrame({"bar": [Timestamp("20130101"), "foo"]})
        assert_frame_equal(result, expected)

        df1 = DataFrame({"bar": Timestamp("20130101")}, index=range(1))
        df2 = DataFrame({"bar": np.nan}, index=range(1, 2))
        result = df1.append(df2)
        expected = DataFrame(
            {"bar": Series([Timestamp("20130101"), np.nan], dtype="M8[ns]")}
        )
        assert_frame_equal(result, expected)

        df1 = DataFrame({"bar": Timestamp("20130101")}, index=range(1))
        df2 = DataFrame({"bar": np.nan}, index=range(1, 2), dtype=object)
        result = df1.append(df2)
        expected = DataFrame(
            {"bar": Series([Timestamp("20130101"), np.nan], dtype="M8[ns]")}
        )
        assert_frame_equal(result, expected)

        df1 = DataFrame({"bar": np.nan}, index=range(1))
        df2 = DataFrame({"bar": Timestamp("20130101")}, index=range(1, 2))
        result = df1.append(df2)
        expected = DataFrame(
            {"bar": Series([np.nan, Timestamp("20130101")], dtype="M8[ns]")}
        )
        assert_frame_equal(result, expected)

        df1 = DataFrame({"bar": Timestamp("20130101")}, index=range(1))
        df2 = DataFrame({"bar": 1}, index=range(1, 2), dtype=object)
        result = df1.append(df2)
        expected = DataFrame({"bar": Series([Timestamp("20130101"), 1])})
        assert_frame_equal(result, expected)

    def test_update(self):
        df = DataFrame(
            [[1.5, np.nan, 3.0], [1.5, np.nan, 3.0], [1.5, np.nan, 3], [1.5, np.nan, 3]]
        )

        other = DataFrame([[3.6, 2.0, np.nan], [np.nan, np.nan, 7]], index=[1, 3])

        df.update(other)

        expected = DataFrame(
            [[1.5, np.nan, 3], [3.6, 2, 3], [1.5, np.nan, 3], [1.5, np.nan, 7.0]]
        )
        assert_frame_equal(df, expected)

    def test_update_dtypes(self):

        # gh 3016
        df = DataFrame(
            [[1.0, 2.0, False, True], [4.0, 5.0, True, False]],
            columns=["A", "B", "bool1", "bool2"],
        )

        other = DataFrame([[45, 45]], index=[0], columns=["A", "B"])
        df.update(other)

        expected = DataFrame(
            [[45.0, 45.0, False, True], [4.0, 5.0, True, False]],
            columns=["A", "B", "bool1", "bool2"],
        )
        assert_frame_equal(df, expected)

    def test_update_nooverwrite(self):
        df = DataFrame(
            [[1.5, np.nan, 3.0], [1.5, np.nan, 3.0], [1.5, np.nan, 3], [1.5, np.nan, 3]]
        )

        other = DataFrame([[3.6, 2.0, np.nan], [np.nan, np.nan, 7]], index=[1, 3])

        df.update(other, overwrite=False)

        expected = DataFrame(
            [[1.5, np.nan, 3], [1.5, 2, 3], [1.5, np.nan, 3], [1.5, np.nan, 3.0]]
        )
        assert_frame_equal(df, expected)

    def test_update_filtered(self):
        df = DataFrame(
            [[1.5, np.nan, 3.0], [1.5, np.nan, 3.0], [1.5, np.nan, 3], [1.5, np.nan, 3]]
        )

        other = DataFrame([[3.6, 2.0, np.nan], [np.nan, np.nan, 7]], index=[1, 3])

        df.update(other, filter_func=lambda x: x > 2)

        expected = DataFrame(
            [[1.5, np.nan, 3], [1.5, np.nan, 3], [1.5, np.nan, 3], [1.5, np.nan, 7.0]]
        )
        assert_frame_equal(df, expected)

    @pytest.mark.parametrize(
        "bad_kwarg, exception, msg",
        [
            # errors must be 'ignore' or 'raise'
            ({"errors": "something"}, ValueError, "The parameter errors must.*"),
            ({"join": "inner"}, NotImplementedError, "Only left join is supported"),
        ],
    )
    def test_update_raise_bad_parameter(self, bad_kwarg, exception, msg):
        df = DataFrame([[1.5, 1, 3.0]])
        with pytest.raises(exception, match=msg):
            df.update(df, **bad_kwarg)

    def test_update_raise_on_overlap(self):
        df = DataFrame(
            [[1.5, 1, 3.0], [1.5, np.nan, 3.0], [1.5, np.nan, 3], [1.5, np.nan, 3]]
        )

        other = DataFrame([[2.0, np.nan], [np.nan, 7]], index=[1, 3], columns=[1, 2])
        with pytest.raises(ValueError, match="Data overlaps"):
            df.update(other, errors="raise")

    @pytest.mark.parametrize("raise_conflict", [True, False])
    def test_update_deprecation(self, raise_conflict):
        df = DataFrame([[1.5, 1, 3.0]])
        other = DataFrame()
        with tm.assert_produces_warning(FutureWarning):
            df.update(other, raise_conflict=raise_conflict)

    def test_update_from_non_df(self):
        d = {"a": Series([1, 2, 3, 4]), "b": Series([5, 6, 7, 8])}
        df = DataFrame(d)

        d["a"] = Series([5, 6, 7, 8])
        df.update(d)

        expected = DataFrame(d)

        assert_frame_equal(df, expected)

        d = {"a": [1, 2, 3, 4], "b": [5, 6, 7, 8]}
        df = DataFrame(d)

        d["a"] = [5, 6, 7, 8]
        df.update(d)

        expected = DataFrame(d)

        assert_frame_equal(df, expected)

    def test_update_datetime_tz(self):
        # GH 25807
        result = DataFrame([pd.Timestamp("2019", tz="UTC")])
        result.update(result)
        expected = DataFrame([pd.Timestamp("2019", tz="UTC")])
        assert_frame_equal(result, expected)

    def test_join_str_datetime(self):
        str_dates = ["20120209", "20120222"]
        dt_dates = [datetime(2012, 2, 9), datetime(2012, 2, 22)]

        A = DataFrame(str_dates, index=range(2), columns=["aa"])
        C = DataFrame([[1, 2], [3, 4]], index=str_dates, columns=dt_dates)

        tst = A.join(C, on="aa")

        assert len(tst.columns) == 3

    def test_join_multiindex_leftright(self):
        # GH 10741
        df1 = pd.DataFrame(
            [
                ["a", "x", 0.471780],
                ["a", "y", 0.774908],
                ["a", "z", 0.563634],
                ["b", "x", -0.353756],
                ["b", "y", 0.368062],
                ["b", "z", -1.721840],
                ["c", "x", 1],
                ["c", "y", 2],
                ["c", "z", 3],
            ],
            columns=["first", "second", "value1"],
        ).set_index(["first", "second"])

        df2 = pd.DataFrame(
            [["a", 10], ["b", 20]], columns=["first", "value2"]
        ).set_index(["first"])

        exp = pd.DataFrame(
            [
                [0.471780, 10],
                [0.774908, 10],
                [0.563634, 10],
                [-0.353756, 20],
                [0.368062, 20],
                [-1.721840, 20],
                [1.000000, np.nan],
                [2.000000, np.nan],
                [3.000000, np.nan],
            ],
            index=df1.index,
            columns=["value1", "value2"],
        )

        # these must be the same results (but columns are flipped)
        assert_frame_equal(df1.join(df2, how="left"), exp)
        assert_frame_equal(df2.join(df1, how="right"), exp[["value2", "value1"]])

        exp_idx = pd.MultiIndex.from_product(
            [["a", "b"], ["x", "y", "z"]], names=["first", "second"]
        )
        exp = pd.DataFrame(
            [
                [0.471780, 10],
                [0.774908, 10],
                [0.563634, 10],
                [-0.353756, 20],
                [0.368062, 20],
                [-1.721840, 20],
            ],
            index=exp_idx,
            columns=["value1", "value2"],
        )

        assert_frame_equal(df1.join(df2, how="right"), exp)
        assert_frame_equal(df2.join(df1, how="left"), exp[["value2", "value1"]])

    def test_concat_named_keys(self):
        # GH 14252
        df = pd.DataFrame({"foo": [1, 2], "bar": [0.1, 0.2]})
        index = Index(["a", "b"], name="baz")
        concatted_named_from_keys = pd.concat([df, df], keys=index)
        expected_named = pd.DataFrame(
            {"foo": [1, 2, 1, 2], "bar": [0.1, 0.2, 0.1, 0.2]},
            index=pd.MultiIndex.from_product((["a", "b"], [0, 1]), names=["baz", None]),
        )
        assert_frame_equal(concatted_named_from_keys, expected_named)

        index_no_name = Index(["a", "b"], name=None)
        concatted_named_from_names = pd.concat(
            [df, df], keys=index_no_name, names=["baz"]
        )
        assert_frame_equal(concatted_named_from_names, expected_named)

        concatted_unnamed = pd.concat([df, df], keys=index_no_name)
        expected_unnamed = pd.DataFrame(
            {"foo": [1, 2, 1, 2], "bar": [0.1, 0.2, 0.1, 0.2]},
            index=pd.MultiIndex.from_product((["a", "b"], [0, 1]), names=[None, None]),
        )
        assert_frame_equal(concatted_unnamed, expected_unnamed)

    def test_concat_axis_parameter(self):
        # GH 14369
        df1 = pd.DataFrame({"A": [0.1, 0.2]}, index=range(2))
        df2 = pd.DataFrame({"A": [0.3, 0.4]}, index=range(2))

        # Index/row/0 DataFrame
        expected_index = pd.DataFrame({"A": [0.1, 0.2, 0.3, 0.4]}, index=[0, 1, 0, 1])

        concatted_index = pd.concat([df1, df2], axis="index")
        assert_frame_equal(concatted_index, expected_index)

        concatted_row = pd.concat([df1, df2], axis="rows")
        assert_frame_equal(concatted_row, expected_index)

        concatted_0 = pd.concat([df1, df2], axis=0)
        assert_frame_equal(concatted_0, expected_index)

        # Columns/1 DataFrame
        expected_columns = pd.DataFrame(
            [[0.1, 0.3], [0.2, 0.4]], index=[0, 1], columns=["A", "A"]
        )

        concatted_columns = pd.concat([df1, df2], axis="columns")
        assert_frame_equal(concatted_columns, expected_columns)

        concatted_1 = pd.concat([df1, df2], axis=1)
        assert_frame_equal(concatted_1, expected_columns)

        series1 = pd.Series([0.1, 0.2])
        series2 = pd.Series([0.3, 0.4])

        # Index/row/0 Series
        expected_index_series = pd.Series([0.1, 0.2, 0.3, 0.4], index=[0, 1, 0, 1])

        concatted_index_series = pd.concat([series1, series2], axis="index")
        assert_series_equal(concatted_index_series, expected_index_series)

        concatted_row_series = pd.concat([series1, series2], axis="rows")
        assert_series_equal(concatted_row_series, expected_index_series)

        concatted_0_series = pd.concat([series1, series2], axis=0)
        assert_series_equal(concatted_0_series, expected_index_series)

        # Columns/1 Series
        expected_columns_series = pd.DataFrame(
            [[0.1, 0.3], [0.2, 0.4]], index=[0, 1], columns=[0, 1]
        )

        concatted_columns_series = pd.concat([series1, series2], axis="columns")
        assert_frame_equal(concatted_columns_series, expected_columns_series)

        concatted_1_series = pd.concat([series1, series2], axis=1)
        assert_frame_equal(concatted_1_series, expected_columns_series)

        # Testing ValueError
        with pytest.raises(ValueError, match="No axis named"):
            pd.concat([series1, series2], axis="something")

    def test_concat_numerical_names(self):
        # #15262  # #12223
        df = pd.DataFrame(
            {"col": range(9)},
            dtype="int32",
            index=(
                pd.MultiIndex.from_product(
                    [["A0", "A1", "A2"], ["B0", "B1", "B2"]], names=[1, 2]
                )
            ),
        )
        result = pd.concat((df.iloc[:2, :], df.iloc[-2:, :]))
        expected = pd.DataFrame(
            {"col": [0, 1, 7, 8]},
            dtype="int32",
            index=pd.MultiIndex.from_tuples(
                [("A0", "B0"), ("A0", "B1"), ("A2", "B1"), ("A2", "B2")], names=[1, 2]
            ),
        )
        tm.assert_frame_equal(result, expected)

    def test_concat_astype_dup_col(self):
        # gh 23049
        df = pd.DataFrame([{"a": "b"}])
        df = pd.concat([df, df], axis=1)

        result = df.astype("category")
        expected = pd.DataFrame(
            np.array(["b", "b"]).reshape(1, 2), columns=["a", "a"]
        ).astype("category")
        tm.assert_frame_equal(result, expected)


class TestDataFrameCombineFirst:
    def test_combine_first_mixed(self):
        a = Series(["a", "b"], index=range(2))
        b = Series(range(2), index=range(2))
        f = DataFrame({"A": a, "B": b})

        a = Series(["a", "b"], index=range(5, 7))
        b = Series(range(2), index=range(5, 7))
        g = DataFrame({"A": a, "B": b})

        exp = pd.DataFrame(
            {"A": list("abab"), "B": [0.0, 1.0, 0.0, 1.0]}, index=[0, 1, 5, 6]
        )
        combined = f.combine_first(g)
        tm.assert_frame_equal(combined, exp)

    def test_combine_first(self, float_frame):
        # disjoint
        head, tail = float_frame[:5], float_frame[5:]

        combined = head.combine_first(tail)
        reordered_frame = float_frame.reindex(combined.index)
        assert_frame_equal(combined, reordered_frame)
        assert tm.equalContents(combined.columns, float_frame.columns)
        assert_series_equal(combined["A"], reordered_frame["A"])

        # same index
        fcopy = float_frame.copy()
        fcopy["A"] = 1
        del fcopy["C"]

        fcopy2 = float_frame.copy()
        fcopy2["B"] = 0
        del fcopy2["D"]

        combined = fcopy.combine_first(fcopy2)

        assert (combined["A"] == 1).all()
        assert_series_equal(combined["B"], fcopy["B"])
        assert_series_equal(combined["C"], fcopy2["C"])
        assert_series_equal(combined["D"], fcopy["D"])

        # overlap
        head, tail = reordered_frame[:10].copy(), reordered_frame
        head["A"] = 1

        combined = head.combine_first(tail)
        assert (combined["A"][:10] == 1).all()

        # reverse overlap
        tail["A"][:10] = 0
        combined = tail.combine_first(head)
        assert (combined["A"][:10] == 0).all()

        # no overlap
        f = float_frame[:10]
        g = float_frame[10:]
        combined = f.combine_first(g)
        assert_series_equal(combined["A"].reindex(f.index), f["A"])
        assert_series_equal(combined["A"].reindex(g.index), g["A"])

        # corner cases
        comb = float_frame.combine_first(DataFrame())
        assert_frame_equal(comb, float_frame)

        comb = DataFrame().combine_first(float_frame)
        assert_frame_equal(comb, float_frame)

        comb = float_frame.combine_first(DataFrame(index=["faz", "boo"]))
        assert "faz" in comb.index

        # #2525
        df = DataFrame({"a": [1]}, index=[datetime(2012, 1, 1)])
        df2 = DataFrame(columns=["b"])
        result = df.combine_first(df2)
        assert "b" in result

    def test_combine_first_mixed_bug(self):
        idx = Index(["a", "b", "c", "e"])
        ser1 = Series([5.0, -9.0, 4.0, 100.0], index=idx)
        ser2 = Series(["a", "b", "c", "e"], index=idx)
        ser3 = Series([12, 4, 5, 97], index=idx)

        frame1 = DataFrame({"col0": ser1, "col2": ser2, "col3": ser3})

        idx = Index(["a", "b", "c", "f"])
        ser1 = Series([5.0, -9.0, 4.0, 100.0], index=idx)
        ser2 = Series(["a", "b", "c", "f"], index=idx)
        ser3 = Series([12, 4, 5, 97], index=idx)

        frame2 = DataFrame({"col1": ser1, "col2": ser2, "col5": ser3})

        combined = frame1.combine_first(frame2)
        assert len(combined.columns) == 5

        # gh 3016 (same as in update)
        df = DataFrame(
            [[1.0, 2.0, False, True], [4.0, 5.0, True, False]],
            columns=["A", "B", "bool1", "bool2"],
        )

        other = DataFrame([[45, 45]], index=[0], columns=["A", "B"])
        result = df.combine_first(other)
        assert_frame_equal(result, df)

        df.loc[0, "A"] = np.nan
        result = df.combine_first(other)
        df.loc[0, "A"] = 45
        assert_frame_equal(result, df)

        # doc example
        df1 = DataFrame(
            {"A": [1.0, np.nan, 3.0, 5.0, np.nan], "B": [np.nan, 2.0, 3.0, np.nan, 6.0]}
        )

        df2 = DataFrame(
            {
                "A": [5.0, 2.0, 4.0, np.nan, 3.0, 7.0],
                "B": [np.nan, np.nan, 3.0, 4.0, 6.0, 8.0],
            }
        )

        result = df1.combine_first(df2)
        expected = DataFrame({"A": [1, 2, 3, 5, 3, 7.0], "B": [np.nan, 2, 3, 4, 6, 8]})
        assert_frame_equal(result, expected)

        # GH3552, return object dtype with bools
        df1 = DataFrame(
            [[np.nan, 3.0, True], [-4.6, np.nan, True], [np.nan, 7.0, False]]
        )
        df2 = DataFrame([[-42.6, np.nan, True], [-5.0, 1.6, False]], index=[1, 2])

        result = df1.combine_first(df2)[2]
        expected = Series([True, True, False], name=2)
        assert_series_equal(result, expected)

        # GH 3593, converting datetime64[ns] incorrectly
        df0 = DataFrame(
            {"a": [datetime(2000, 1, 1), datetime(2000, 1, 2), datetime(2000, 1, 3)]}
        )
        df1 = DataFrame({"a": [None, None, None]})
        df2 = df1.combine_first(df0)
        assert_frame_equal(df2, df0)

        df2 = df0.combine_first(df1)
        assert_frame_equal(df2, df0)

        df0 = DataFrame(
            {"a": [datetime(2000, 1, 1), datetime(2000, 1, 2), datetime(2000, 1, 3)]}
        )
        df1 = DataFrame({"a": [datetime(2000, 1, 2), None, None]})
        df2 = df1.combine_first(df0)
        result = df0.copy()
        result.iloc[0, :] = df1.iloc[0, :]
        assert_frame_equal(df2, result)

        df2 = df0.combine_first(df1)
        assert_frame_equal(df2, df0)

    def test_combine_first_align_nan(self):
        # GH 7509 (not fixed)
        dfa = pd.DataFrame([[pd.Timestamp("2011-01-01"), 2]], columns=["a", "b"])
        dfb = pd.DataFrame([[4], [5]], columns=["b"])
        assert dfa["a"].dtype == "datetime64[ns]"
        assert dfa["b"].dtype == "int64"

        res = dfa.combine_first(dfb)
        exp = pd.DataFrame(
            {"a": [pd.Timestamp("2011-01-01"), pd.NaT], "b": [2.0, 5.0]},
            columns=["a", "b"],
        )
        tm.assert_frame_equal(res, exp)
        assert res["a"].dtype == "datetime64[ns]"
        # ToDo: this must be int64
        assert res["b"].dtype == "float64"

        res = dfa.iloc[:0].combine_first(dfb)
        exp = pd.DataFrame({"a": [np.nan, np.nan], "b": [4, 5]}, columns=["a", "b"])
        tm.assert_frame_equal(res, exp)
        # ToDo: this must be datetime64
        assert res["a"].dtype == "float64"
        # ToDo: this must be int64
        assert res["b"].dtype == "int64"

    def test_combine_first_timezone(self):
        # see gh-7630
        data1 = pd.to_datetime("20100101 01:01").tz_localize("UTC")
        df1 = pd.DataFrame(
            columns=["UTCdatetime", "abc"],
            data=data1,
            index=pd.date_range("20140627", periods=1),
        )
        data2 = pd.to_datetime("20121212 12:12").tz_localize("UTC")
        df2 = pd.DataFrame(
            columns=["UTCdatetime", "xyz"],
            data=data2,
            index=pd.date_range("20140628", periods=1),
        )
        res = df2[["UTCdatetime"]].combine_first(df1)
        exp = pd.DataFrame(
            {
                "UTCdatetime": [
                    pd.Timestamp("2010-01-01 01:01", tz="UTC"),
                    pd.Timestamp("2012-12-12 12:12", tz="UTC"),
                ],
                "abc": [pd.Timestamp("2010-01-01 01:01:00", tz="UTC"), pd.NaT],
            },
            columns=["UTCdatetime", "abc"],
            index=pd.date_range("20140627", periods=2, freq="D"),
        )
        tm.assert_frame_equal(res, exp)
        assert res["UTCdatetime"].dtype == "datetime64[ns, UTC]"
        assert res["abc"].dtype == "datetime64[ns, UTC]"

        # see gh-10567
        dts1 = pd.date_range("2015-01-01", "2015-01-05", tz="UTC")
        df1 = pd.DataFrame({"DATE": dts1})
        dts2 = pd.date_range("2015-01-03", "2015-01-05", tz="UTC")
        df2 = pd.DataFrame({"DATE": dts2})

        res = df1.combine_first(df2)
        tm.assert_frame_equal(res, df1)
        assert res["DATE"].dtype == "datetime64[ns, UTC]"

        dts1 = pd.DatetimeIndex(
            ["2011-01-01", "NaT", "2011-01-03", "2011-01-04"], tz="US/Eastern"
        )
        df1 = pd.DataFrame({"DATE": dts1}, index=[1, 3, 5, 7])
        dts2 = pd.DatetimeIndex(
            ["2012-01-01", "2012-01-02", "2012-01-03"], tz="US/Eastern"
        )
        df2 = pd.DataFrame({"DATE": dts2}, index=[2, 4, 5])

        res = df1.combine_first(df2)
        exp_dts = pd.DatetimeIndex(
            [
                "2011-01-01",
                "2012-01-01",
                "NaT",
                "2012-01-02",
                "2011-01-03",
                "2011-01-04",
            ],
            tz="US/Eastern",
        )
        exp = pd.DataFrame({"DATE": exp_dts}, index=[1, 2, 3, 4, 5, 7])
        tm.assert_frame_equal(res, exp)

        # different tz
        dts1 = pd.date_range("2015-01-01", "2015-01-05", tz="US/Eastern")
        df1 = pd.DataFrame({"DATE": dts1})
        dts2 = pd.date_range("2015-01-03", "2015-01-05")
        df2 = pd.DataFrame({"DATE": dts2})

        # if df1 doesn't have NaN, keep its dtype
        res = df1.combine_first(df2)
        tm.assert_frame_equal(res, df1)
        assert res["DATE"].dtype == "datetime64[ns, US/Eastern]"

        dts1 = pd.date_range("2015-01-01", "2015-01-02", tz="US/Eastern")
        df1 = pd.DataFrame({"DATE": dts1})
        dts2 = pd.date_range("2015-01-01", "2015-01-03")
        df2 = pd.DataFrame({"DATE": dts2})

        res = df1.combine_first(df2)
        exp_dts = [
            pd.Timestamp("2015-01-01", tz="US/Eastern"),
            pd.Timestamp("2015-01-02", tz="US/Eastern"),
            pd.Timestamp("2015-01-03"),
        ]
        exp = pd.DataFrame({"DATE": exp_dts})
        tm.assert_frame_equal(res, exp)
        assert res["DATE"].dtype == "object"

    def test_combine_first_timedelta(self):
        data1 = pd.TimedeltaIndex(["1 day", "NaT", "3 day", "4day"])
        df1 = pd.DataFrame({"TD": data1}, index=[1, 3, 5, 7])
        data2 = pd.TimedeltaIndex(["10 day", "11 day", "12 day"])
        df2 = pd.DataFrame({"TD": data2}, index=[2, 4, 5])

        res = df1.combine_first(df2)
        exp_dts = pd.TimedeltaIndex(
            ["1 day", "10 day", "NaT", "11 day", "3 day", "4 day"]
        )
        exp = pd.DataFrame({"TD": exp_dts}, index=[1, 2, 3, 4, 5, 7])
        tm.assert_frame_equal(res, exp)
        assert res["TD"].dtype == "timedelta64[ns]"

    def test_combine_first_period(self):
        data1 = pd.PeriodIndex(["2011-01", "NaT", "2011-03", "2011-04"], freq="M")
        df1 = pd.DataFrame({"P": data1}, index=[1, 3, 5, 7])
        data2 = pd.PeriodIndex(["2012-01-01", "2012-02", "2012-03"], freq="M")
        df2 = pd.DataFrame({"P": data2}, index=[2, 4, 5])

        res = df1.combine_first(df2)
        exp_dts = pd.PeriodIndex(
            ["2011-01", "2012-01", "NaT", "2012-02", "2011-03", "2011-04"], freq="M"
        )
        exp = pd.DataFrame({"P": exp_dts}, index=[1, 2, 3, 4, 5, 7])
        tm.assert_frame_equal(res, exp)
        assert res["P"].dtype == data1.dtype

        # different freq
        dts2 = pd.PeriodIndex(["2012-01-01", "2012-01-02", "2012-01-03"], freq="D")
        df2 = pd.DataFrame({"P": dts2}, index=[2, 4, 5])

        res = df1.combine_first(df2)
        exp_dts = [
            pd.Period("2011-01", freq="M"),
            pd.Period("2012-01-01", freq="D"),
            pd.NaT,
            pd.Period("2012-01-02", freq="D"),
            pd.Period("2011-03", freq="M"),
            pd.Period("2011-04", freq="M"),
        ]
        exp = pd.DataFrame({"P": exp_dts}, index=[1, 2, 3, 4, 5, 7])
        tm.assert_frame_equal(res, exp)
        assert res["P"].dtype == "object"

    def test_combine_first_int(self):
        # GH14687 - integer series that do no align exactly

        df1 = pd.DataFrame({"a": [0, 1, 3, 5]}, dtype="int64")
        df2 = pd.DataFrame({"a": [1, 4]}, dtype="int64")

        res = df1.combine_first(df2)
        tm.assert_frame_equal(res, df1)
        assert res["a"].dtype == "int64"

    @pytest.mark.parametrize("val", [1, 1.0])
    def test_combine_first_with_asymmetric_other(self, val):
        # see gh-20699
        df1 = pd.DataFrame({"isNum": [val]})
        df2 = pd.DataFrame({"isBool": [True]})

        res = df1.combine_first(df2)
        exp = pd.DataFrame({"isBool": [True], "isNum": [val]})

        tm.assert_frame_equal(res, exp)

    def test_concat_datetime_datetime64_frame(self):
        # #2624
        rows = []
        rows.append([datetime(2010, 1, 1), 1])
        rows.append([datetime(2010, 1, 2), "hi"])

        df2_obj = DataFrame.from_records(rows, columns=["date", "test"])

        ind = date_range(start="2000/1/1", freq="D", periods=10)
        df1 = DataFrame({"date": ind, "test": range(10)})

        # it works!
        pd.concat([df1, df2_obj])


class TestDataFrameUpdate:
    def test_update_nan(self):
        # #15593 #15617
        # test 1
        df1 = DataFrame({"A": [1.0, 2, 3], "B": date_range("2000", periods=3)})
        df2 = DataFrame({"A": [None, 2, 3]})
        expected = df1.copy()
        df1.update(df2, overwrite=False)

        tm.assert_frame_equal(df1, expected)

        # test 2
        df1 = DataFrame({"A": [1.0, None, 3], "B": date_range("2000", periods=3)})
        df2 = DataFrame({"A": [None, 2, 3]})
        expected = DataFrame({"A": [1.0, 2, 3], "B": date_range("2000", periods=3)})
        df1.update(df2, overwrite=False)

        tm.assert_frame_equal(df1, expected)