/pandas/tests/series/test_ufunc.py

from collections import deque
import string

import numpy as np
import pytest

import pandas as pd
import pandas._testing as tm
from pandas.arrays import SparseArray

UNARY_UFUNCS = [np.positive, np.floor, np.exp]
BINARY_UFUNCS = [np.add, np.logaddexp]  # dunder op
SPARSE = [True, False]
SPARSE_IDS = ["sparse", "dense"]
SHUFFLE = [True, False]


@pytest.fixture
def arrays_for_binary_ufunc():
    """
    A pair of random, length-100 integer-dtype arrays, that are mostly 0.
    """
    a1 = np.random.randint(0, 10, 100, dtype="int64")
    a2 = np.random.randint(0, 10, 100, dtype="int64")
    a1[::3] = 0
    a2[::4] = 0
    return a1, a2


@pytest.mark.parametrize("ufunc", UNARY_UFUNCS)
@pytest.mark.parametrize("sparse", SPARSE, ids=SPARSE_IDS)
def test_unary_ufunc(ufunc, sparse):
    # Test that ufunc(pd.Series) == pd.Series(ufunc)
    array = np.random.randint(0, 10, 10, dtype="int64")
    array[::2] = 0
    if sparse:
        array = SparseArray(array, dtype=pd.SparseDtype("int64", 0))

    index = list(string.ascii_letters[:10])
    name = "name"
    series = pd.Series(array, index=index, name=name)

    result = ufunc(series)
    expected = pd.Series(ufunc(array), index=index, name=name)
    tm.assert_series_equal(result, expected)


@pytest.mark.parametrize("ufunc", BINARY_UFUNCS)
@pytest.mark.parametrize("sparse", SPARSE, ids=SPARSE_IDS)
@pytest.mark.parametrize("flip", [True, False], ids=["flipped", "straight"])
def test_binary_ufunc_with_array(flip, sparse, ufunc, arrays_for_binary_ufunc):
    # Test that ufunc(pd.Series(a), array) == pd.Series(ufunc(a, b))
    a1, a2 = arrays_for_binary_ufunc
    if sparse:
        a1 = SparseArray(a1, dtype=pd.SparseDtype("int64", 0))
        a2 = SparseArray(a2, dtype=pd.SparseDtype("int64", 0))

    name = "name"  # op(pd.Series, array) preserves the name.
    series = pd.Series(a1, name=name)
    other = a2

    array_args = (a1, a2)
    series_args = (series, other)  # ufunc(series, array)

    if flip:
        array_args = reversed(array_args)
        series_args = reversed(series_args)  # ufunc(array, series)

    expected = pd.Series(ufunc(*array_args), name=name)
    result = ufunc(*series_args)
    tm.assert_series_equal(result, expected)


@pytest.mark.parametrize("ufunc", BINARY_UFUNCS)
@pytest.mark.parametrize("sparse", SPARSE, ids=SPARSE_IDS)
@pytest.mark.parametrize("flip", [True, False], ids=["flipped", "straight"])
def test_binary_ufunc_with_index(flip, sparse, ufunc, arrays_for_binary_ufunc):
    # Test that
    #   * func(pd.Series(a), pd.Series(b)) == pd.Series(ufunc(a, b))
    #   * ufunc(Index, pd.Series) dispatches to pd.Series (returns a pd.Series)
    a1, a2 = arrays_for_binary_ufunc
    if sparse:
        a1 = SparseArray(a1, dtype=pd.SparseDtype("int64", 0))
        a2 = SparseArray(a2, dtype=pd.SparseDtype("int64", 0))

    name = "name"  # op(pd.Series, array) preserves the name.
    series = pd.Series(a1, name=name)
    other = pd.Index(a2, name=name).astype("int64")

    array_args = (a1, a2)
    series_args = (series, other)  # ufunc(series, array)

    if flip:
        array_args = reversed(array_args)
        series_args = reversed(series_args)  # ufunc(array, series)

    expected = pd.Series(ufunc(*array_args), name=name)
    result = ufunc(*series_args)
    tm.assert_series_equal(result, expected)


@pytest.mark.parametrize("ufunc", BINARY_UFUNCS)
@pytest.mark.parametrize("sparse", SPARSE, ids=SPARSE_IDS)
@pytest.mark.parametrize("shuffle", [True, False], ids=["unaligned", "aligned"])
@pytest.mark.parametrize("flip", [True, False], ids=["flipped", "straight"])
def test_binary_ufunc_with_series(
    flip, shuffle, sparse, ufunc, arrays_for_binary_ufunc
):
    # Test that
    #   * func(pd.Series(a), pd.Series(b)) == pd.Series(ufunc(a, b))
    #   with alignment between the indices
    a1, a2 = arrays_for_binary_ufunc
    if sparse:
        a1 = SparseArray(a1, dtype=pd.SparseDtype("int64", 0))
        a2 = SparseArray(a2, dtype=pd.SparseDtype("int64", 0))

    name = "name"  # op(pd.Series, array) preserves the name.
    series = pd.Series(a1, name=name)
    other = pd.Series(a2, name=name)

    idx = np.random.permutation(len(a1))

    if shuffle:
        other = other.take(idx)
        if flip:
            index = other.align(series)[0].index
        else:
            index = series.align(other)[0].index
    else:
        index = series.index

    array_args = (a1, a2)
    series_args = (series, other)  # ufunc(series, array)

    if flip:
        array_args = tuple(reversed(array_args))
        series_args = tuple(reversed(series_args))  # ufunc(array, series)

    expected = pd.Series(ufunc(*array_args), index=index, name=name)
    result = ufunc(*series_args)
    tm.assert_series_equal(result, expected)


@pytest.mark.parametrize("ufunc", BINARY_UFUNCS)
@pytest.mark.parametrize("sparse", SPARSE, ids=SPARSE_IDS)
@pytest.mark.parametrize("flip", [True, False])
def test_binary_ufunc_scalar(ufunc, sparse, flip, arrays_for_binary_ufunc):
    # Test that
    #   * ufunc(pd.Series, scalar) == pd.Series(ufunc(array, scalar))
    #   * ufunc(pd.Series, scalar) == ufunc(scalar, pd.Series)
    array, _ = arrays_for_binary_ufunc
    if sparse:
        array = SparseArray(array)
    other = 2
    series = pd.Series(array, name="name")

    series_args = (series, other)
    array_args = (array, other)

    if flip:
        series_args = tuple(reversed(series_args))
        array_args = tuple(reversed(array_args))

    expected = pd.Series(ufunc(*array_args), name="name")
    result = ufunc(*series_args)

    tm.assert_series_equal(result, expected)


@pytest.mark.parametrize("ufunc", [np.divmod])  # TODO: any others?
@pytest.mark.parametrize("sparse", SPARSE, ids=SPARSE_IDS)
@pytest.mark.parametrize("shuffle", SHUFFLE)
@pytest.mark.filterwarnings("ignore:divide by zero:RuntimeWarning")
def test_multiple_output_binary_ufuncs(ufunc, sparse, shuffle, arrays_for_binary_ufunc):
    # Test that
    #  the same conditions from binary_ufunc_scalar apply to
    #  ufuncs with multiple outputs.
    if sparse and ufunc is np.divmod:
        pytest.skip("sparse divmod not implemented.")

    a1, a2 = arrays_for_binary_ufunc
    # work around https://github.com/pandas-dev/pandas/issues/26987
    a1[a1 == 0] = 1
    a2[a2 == 0] = 1

    if sparse:
        a1 = SparseArray(a1, dtype=pd.SparseDtype("int64", 0))
        a2 = SparseArray(a2, dtype=pd.SparseDtype("int64", 0))

    s1 = pd.Series(a1)
    s2 = pd.Series(a2)

    if shuffle:
        # ensure we align before applying the ufunc
        s2 = s2.sample(frac=1)

    expected = ufunc(a1, a2)
    assert isinstance(expected, tuple)

    result = ufunc(s1, s2)
    assert isinstance(result, tuple)
    tm.assert_series_equal(result[0], pd.Series(expected[0]))
    tm.assert_series_equal(result[1], pd.Series(expected[1]))


@pytest.mark.parametrize("sparse", SPARSE, ids=SPARSE_IDS)
def test_multiple_output_ufunc(sparse, arrays_for_binary_ufunc):
    # Test that the same conditions from unary input apply to multi-output
    # ufuncs
    array, _ = arrays_for_binary_ufunc

    if sparse:
        array = SparseArray(array)

    series = pd.Series(array, name="name")
    result = np.modf(series)
    expected = np.modf(array)

    assert isinstance(result, tuple)
    assert isinstance(expected, tuple)

    tm.assert_series_equal(result[0], pd.Series(expected[0], name="name"))
    tm.assert_series_equal(result[1], pd.Series(expected[1], name="name"))


@pytest.mark.parametrize("sparse", SPARSE, ids=SPARSE_IDS)
@pytest.mark.parametrize("ufunc", BINARY_UFUNCS)
def test_binary_ufunc_drops_series_name(ufunc, sparse, arrays_for_binary_ufunc):
    # Drop the names when they differ.
    a1, a2 = arrays_for_binary_ufunc
    s1 = pd.Series(a1, name="a")
    s2 = pd.Series(a2, name="b")

    result = ufunc(s1, s2)
    assert result.name is None


def test_object_series_ok():
    class Dummy:
        def __init__(self, value):
            self.value = value

        def __add__(self, other):
            return self.value + other.value

    arr = np.array([Dummy(0), Dummy(1)])
    ser = pd.Series(arr)
    tm.assert_series_equal(np.add(ser, ser), pd.Series(np.add(ser, arr)))
    tm.assert_series_equal(np.add(ser, Dummy(1)), pd.Series(np.add(ser, Dummy(1))))


@pytest.mark.parametrize(
    "values",
    [
        pd.array([1, 3, 2], dtype="int64"),
        pd.array([1, 10, 0], dtype="Sparse[int]"),
        pd.to_datetime(["2000", "2010", "2001"]),
        pd.to_datetime(["2000", "2010", "2001"]).tz_localize("CET"),
        pd.to_datetime(["2000", "2010", "2001"]).to_period(freq="D"),
    ],
)
def test_reduce(values):
    a = pd.Series(values)
    assert np.maximum.reduce(a) == values[1]


@pytest.mark.parametrize("type_", [list, deque, tuple])
def test_binary_ufunc_other_types(type_):
    a = pd.Series([1, 2, 3], name="name")
    b = type_([3, 4, 5])

    result = np.add(a, b)
    expected = pd.Series(np.add(a.to_numpy(), b), name="name")
    tm.assert_series_equal(result, expected)


def test_object_dtype_ok():
    class Thing:
        def __init__(self, value):
            self.value = value

        def __add__(self, other):
            other = getattr(other, "value", other)
            return type(self)(self.value + other)

        def __eq__(self, other) -> bool:
            return type(other) is Thing and self.value == other.value

        def __repr__(self) -> str:
            return f"Thing({self.value})"

    s = pd.Series([Thing(1), Thing(2)])
    result = np.add(s, Thing(1))
    expected = pd.Series([Thing(2), Thing(3)])
    tm.assert_series_equal(result, expected)


def test_outer():
    # https://github.com/pandas-dev/pandas/issues/27186
    s = pd.Series([1, 2, 3])
    o = np.array([1, 2, 3])

    with pytest.raises(NotImplementedError, match=tm.EMPTY_STRING_PATTERN):
        np.subtract.outer(s, o)