test_categorical.py

"""
This file contains a minimal set of tests for compliance with the extension
array interface test suite, and should contain no other tests.
The test suite for the full functionality of the array is located in
`pandas/tests/arrays/`.

The tests in this file are inherited from the BaseExtensionTests, and only
minimal tweaks should be applied to get the tests passing (by overwriting a
parent method).

Additional tests should either be added to one of the BaseExtensionTests
classes (if they are relevant for the extension interface for all dtypes), or
be added to the array-specific tests in `pandas/tests/arrays/`.

"""
import string

import numpy as np
import pytest

import pandas as pd
from pandas import Categorical, CategoricalIndex, Timestamp
import pandas._testing as tm
from pandas.api.types import CategoricalDtype
from pandas.tests.extension import base


def make_data():
    while True:
        values = np.random.choice(list(string.ascii_letters), size=100)
        # ensure we meet the requirements
        # 1. first two not null
        # 2. first and second are different
        if values[0] != values[1]:
            break
    return values


@pytest.fixture
def dtype():
    return CategoricalDtype()


@pytest.fixture
def data():
    """Length-100 array for this type.

    * data[0] and data[1] should both be non missing
    * data[0] and data[1] should not gbe equal
    """
    return Categorical(make_data())


@pytest.fixture
def data_missing():
    """Length 2 array with [NA, Valid]"""
    return Categorical([np.nan, "A"])


@pytest.fixture
def data_for_sorting():
    return Categorical(["A", "B", "C"], categories=["C", "A", "B"], ordered=True)


@pytest.fixture
def data_missing_for_sorting():
    return Categorical(["A", None, "B"], categories=["B", "A"], ordered=True)


@pytest.fixture
def na_value():
    return np.nan


@pytest.fixture
def data_for_grouping():
    return Categorical(["a", "a", None, None, "b", "b", "a", "c"])


class TestDtype(base.BaseDtypeTests):
    pass


class TestInterface(base.BaseInterfaceTests):
    @pytest.mark.skip(reason="Memory usage doesn't match")
    def test_memory_usage(self, data):
        # Is this deliberate?
        super().test_memory_usage(data)

    def test_contains(self, data, data_missing):
        # GH-37867
        # na value handling in Categorical.__contains__ is deprecated.
        # See base.BaseInterFaceTests.test_contains for more details.

        na_value = data.dtype.na_value
        # ensure data without missing values
        data = data[~data.isna()]

        # first elements are non-missing
        assert data[0] in data
        assert data_missing[0] in data_missing

        # check the presence of na_value
        assert na_value in data_missing
        assert na_value not in data

        # Categoricals can contain other nan-likes than na_value
        for na_value_obj in tm.NULL_OBJECTS:
            if na_value_obj is na_value:
                continue
            assert na_value_obj not in data
            assert na_value_obj in data_missing  # this line differs from super method


class TestConstructors(base.BaseConstructorsTests):
    pass


class TestReshaping(base.BaseReshapingTests):
    @pytest.mark.xfail(reason="Deliberately upcast to object?")
    def test_concat_with_reindex(self, data):
        super().test_concat_with_reindex(data)


class TestGetitem(base.BaseGetitemTests):
    @pytest.mark.skip(reason="Backwards compatibility")
    def test_getitem_scalar(self, data):
        # CategoricalDtype.type isn't "correct" since it should
        # be a parent of the elements (object). But don't want
        # to break things by changing.
        super().test_getitem_scalar(data)


class TestSetitem(base.BaseSetitemTests):
    pass


class TestMissing(base.BaseMissingTests):
    @pytest.mark.skip(reason="Not implemented")
    def test_fillna_limit_pad(self, data_missing):
        super().test_fillna_limit_pad(data_missing)

    @pytest.mark.skip(reason="Not implemented")
    def test_fillna_limit_backfill(self, data_missing):
        super().test_fillna_limit_backfill(data_missing)


class TestReduce(base.BaseNoReduceTests):
    pass


class TestMethods(base.BaseMethodsTests):
    @pytest.mark.skip(reason="Unobserved categories included")
    def test_value_counts(self, all_data, dropna):
        return super().test_value_counts(all_data, dropna)

    def test_combine_add(self, data_repeated):
        # GH 20825
        # When adding categoricals in combine, result is a string
        orig_data1, orig_data2 = data_repeated(2)
        s1 = pd.Series(orig_data1)
        s2 = pd.Series(orig_data2)
        result = s1.combine(s2, lambda x1, x2: x1 + x2)
        expected = pd.Series(
            [a + b for (a, b) in zip(list(orig_data1), list(orig_data2))]
        )
        self.assert_series_equal(result, expected)

        val = s1.iloc[0]
        result = s1.combine(val, lambda x1, x2: x1 + x2)
        expected = pd.Series([a + val for a in list(orig_data1)])
        self.assert_series_equal(result, expected)

    @pytest.mark.skip(reason="Not Applicable")
    def test_fillna_length_mismatch(self, data_missing):
        super().test_fillna_length_mismatch(data_missing)


class TestCasting(base.BaseCastingTests):
    @pytest.mark.parametrize("cls", [Categorical, CategoricalIndex])
    @pytest.mark.parametrize("values", [[1, np.nan], [Timestamp("2000"), pd.NaT]])
    def test_cast_nan_to_int(self, cls, values):
        # GH 28406
        s = cls(values)

        msg = "Cannot (cast|convert)"
        with pytest.raises((ValueError, TypeError), match=msg):
            s.astype(int)

    @pytest.mark.parametrize(
        "expected",
        [
            pd.Series(["2019", "2020"], dtype="datetime64[ns, UTC]"),
            pd.Series([0, 0], dtype="timedelta64[ns]"),
            pd.Series([pd.Period("2019"), pd.Period("2020")], dtype="period[A-DEC]"),
            pd.Series([pd.Interval(0, 1), pd.Interval(1, 2)], dtype="interval"),
            pd.Series([1, np.nan], dtype="Int64"),
        ],
    )
    def test_cast_category_to_extension_dtype(self, expected):
        # GH 28668
        result = expected.astype("category").astype(expected.dtype)

        tm.assert_series_equal(result, expected)

    @pytest.mark.parametrize(
        "dtype, expected",
        [
            (
                "datetime64[ns]",
                np.array(["2015-01-01T00:00:00.000000000"], dtype="datetime64[ns]"),
            ),
            (
                "datetime64[ns, MET]",
                pd.DatetimeIndex(
                    [Timestamp("2015-01-01 00:00:00+0100", tz="MET")]
                ).array,
            ),
        ],
    )
    def test_consistent_casting(self, dtype, expected):
        # GH 28448
        result = Categorical(["2015-01-01"]).astype(dtype)
        assert result == expected


class TestArithmeticOps(base.BaseArithmeticOpsTests):
    def test_arith_frame_with_scalar(self, data, all_arithmetic_operators, request):
        # frame & scalar
        op_name = all_arithmetic_operators
        if op_name == "__rmod__":
            request.node.add_marker(
                pytest.mark.xfail(
                    reason="rmod never called when string is first argument"
                )
            )
        super().test_arith_frame_with_scalar(data, op_name)

    def test_arith_series_with_scalar(self, data, all_arithmetic_operators, request):
        op_name = all_arithmetic_operators
        if op_name == "__rmod__":
            request.node.add_marker(
                pytest.mark.xfail(
                    reason="rmod never called when string is first argument"
                )
            )
        super().test_arith_series_with_scalar(data, op_name)

    def test_add_series_with_extension_array(self, data):
        ser = pd.Series(data)
        with pytest.raises(TypeError, match="cannot perform|unsupported operand"):
            ser + data

    def test_divmod_series_array(self):
        # GH 23287
        # skipping because it is not implemented
        pass

    def _check_divmod_op(self, s, op, other, exc=NotImplementedError):
        return super()._check_divmod_op(s, op, other, exc=TypeError)


class TestComparisonOps(base.BaseComparisonOpsTests):
    def _compare_other(self, s, data, op_name, other):
        op = self.get_op_from_name(op_name)
        if op_name == "__eq__":
            result = op(s, other)
            expected = s.combine(other, lambda x, y: x == y)
            assert (result == expected).all()

        elif op_name == "__ne__":
            result = op(s, other)
            expected = s.combine(other, lambda x, y: x != y)
            assert (result == expected).all()

        else:
            msg = "Unordered Categoricals can only compare equality or not"
            with pytest.raises(TypeError, match=msg):
                op(data, other)

    @pytest.mark.parametrize(
        "categories",
        [["a", "b"], [0, 1], [Timestamp("2019"), Timestamp("2020")]],
    )
    def test_not_equal_with_na(self, categories):
        # https://github.com/pandas-dev/pandas/issues/32276
        c1 = Categorical.from_codes([-1, 0], categories=categories)
        c2 = Categorical.from_codes([0, 1], categories=categories)

        result = c1 != c2

        assert result.all()


class TestParsing(base.BaseParsingTests):
    pass