from functools import partial

import numpy as np
import pytest

import pandas.util._test_decorators as td

from pandas.core.dtypes.common import is_integer_dtype

import pandas as pd
from pandas import (
    Series,
    isna,
)
import pandas._testing as tm
from pandas.core import nanops

use_bn = nanops._USE_BOTTLENECK


@pytest.fixture
def disable_bottleneck(monkeypatch):
    with monkeypatch.context() as m:
        m.setattr(nanops, "_USE_BOTTLENECK", False)
        yield


@pytest.fixture
def arr_shape():
    return 11, 7


@pytest.fixture
def arr_float(arr_shape):
    return np.random.default_rng(2).standard_normal(arr_shape)


@pytest.fixture
def arr_complex(arr_float):
    return arr_float + arr_float * 1j


@pytest.fixture
def arr_int(arr_shape):
    return np.random.default_rng(2).integers(-10, 10, arr_shape)


@pytest.fixture
def arr_bool(arr_shape):
    return np.random.default_rng(2).integers(0, 2, arr_shape) == 0


@pytest.fixture
def arr_str(arr_float):
    return np.abs(arr_float).astype("S")


@pytest.fixture
def arr_utf(arr_float):
    return np.abs(arr_float).astype("U")


@pytest.fixture
def arr_date(arr_shape):
    return np.random.default_rng(2).integers(0, 20000, arr_shape).astype("M8[ns]")


@pytest.fixture
def arr_tdelta(arr_shape):
    return np.random.default_rng(2).integers(0, 20000, arr_shape).astype("m8[ns]")


@pytest.fixture
def arr_nan(arr_shape):
    return np.tile(np.nan, arr_shape)


@pytest.fixture
def arr_float_nan(arr_float, arr_nan):
    return np.vstack([arr_float, arr_nan])


@pytest.fixture
def arr_nan_float1(arr_nan, arr_float):
    return np.vstack([arr_nan, arr_float])


@pytest.fixture
def arr_nan_nan(arr_nan):
    return np.vstack([arr_nan, arr_nan])


@pytest.fixture
def arr_inf(arr_float):
    return arr_float * np.inf


@pytest.fixture
def arr_float_inf(arr_float, arr_inf):
    return np.vstack([arr_float, arr_inf])


@pytest.fixture
def arr_nan_inf(arr_nan, arr_inf):
    return np.vstack([arr_nan, arr_inf])


@pytest.fixture
def arr_float_nan_inf(arr_float, arr_nan, arr_inf):
    return np.vstack([arr_float, arr_nan, arr_inf])


@pytest.fixture
def arr_nan_nan_inf(arr_nan, arr_inf):
    return np.vstack([arr_nan, arr_nan, arr_inf])


@pytest.fixture
def arr_obj(
    arr_float, arr_int, arr_bool, arr_complex, arr_str, arr_utf, arr_date, arr_tdelta
):
    return np.vstack(
        [
            arr_float.astype("O"),
            arr_int.astype("O"),
            arr_bool.astype("O"),
            arr_complex.astype("O"),
            arr_str.astype("O"),
            arr_utf.astype("O"),
            arr_date.astype("O"),
            arr_tdelta.astype("O"),
        ]
    )


@pytest.fixture
def arr_nan_nanj(arr_nan):
    with np.errstate(invalid="ignore"):
        return arr_nan + arr_nan * 1j


@pytest.fixture
def arr_complex_nan(arr_complex, arr_nan_nanj):
    with np.errstate(invalid="ignore"):
        return np.vstack([arr_complex, arr_nan_nanj])


@pytest.fixture
def arr_nan_infj(arr_inf):
    with np.errstate(invalid="ignore"):
        return arr_inf * 1j


@pytest.fixture
def arr_complex_nan_infj(arr_complex, arr_nan_infj):
    with np.errstate(invalid="ignore"):
        return np.vstack([arr_complex, arr_nan_infj])


@pytest.fixture
def arr_float_1d(arr_float):
    return arr_float[:, 0]


@pytest.fixture
def arr_nan_1d(arr_nan):
    return arr_nan[:, 0]


@pytest.fixture
def arr_float_nan_1d(arr_float_nan):
    return arr_float_nan[:, 0]


@pytest.fixture
def arr_float1_nan_1d(arr_float1_nan):
    return arr_float1_nan[:, 0]


@pytest.fixture
def arr_nan_float1_1d(arr_nan_float1):
    return arr_nan_float1[:, 0]


class TestnanopsDataFrame:
    def setup_method(self):
        nanops._USE_BOTTLENECK = False

        arr_shape = (11, 7)

        self.arr_float = np.random.default_rng(2).standard_normal(arr_shape)
        self.arr_float1 = np.random.default_rng(2).standard_normal(arr_shape)
        self.arr_complex = self.arr_float + self.arr_float1 * 1j
        self.arr_int = np.random.default_rng(2).integers(-10, 10, arr_shape)
        self.arr_bool = np.random.default_rng(2).integers(0, 2, arr_shape) == 0
        self.arr_str = np.abs(self.arr_float).astype("S")
        self.arr_utf = np.abs(self.arr_float).astype("U")
        self.arr_date = (
            np.random.default_rng(2).integers(0, 20000, arr_shape).astype("M8[ns]")
        )
        self.arr_tdelta = (
            np.random.default_rng(2).integers(0, 20000, arr_shape).astype("m8[ns]")
        )

        self.arr_nan = np.tile(np.nan, arr_shape)
        self.arr_float_nan = np.vstack([self.arr_float, self.arr_nan])
        self.arr_float1_nan = np.vstack([self.arr_float1, self.arr_nan])
        self.arr_nan_float1 = np.vstack([self.arr_nan, self.arr_float1])
        self.arr_nan_nan = np.vstack([self.arr_nan, self.arr_nan])

        self.arr_inf = self.arr_float * np.inf
        self.arr_float_inf = np.vstack([self.arr_float, self.arr_inf])

        self.arr_nan_inf = np.vstack([self.arr_nan, self.arr_inf])
        self.arr_float_nan_inf = np.vstack([self.arr_float, self.arr_nan, self.arr_inf])
        self.arr_nan_nan_inf = np.vstack([self.arr_nan, self.arr_nan, self.arr_inf])
        self.arr_obj = np.vstack(
            [
                self.arr_float.astype("O"),
                self.arr_int.astype("O"),
                self.arr_bool.astype("O"),
                self.arr_complex.astype("O"),
                self.arr_str.astype("O"),
                self.arr_utf.astype("O"),
                self.arr_date.astype("O"),
                self.arr_tdelta.astype("O"),
            ]
        )

        with np.errstate(invalid="ignore"):
            self.arr_nan_nanj = self.arr_nan + self.arr_nan * 1j
            self.arr_complex_nan = np.vstack([self.arr_complex, self.arr_nan_nanj])

            self.arr_nan_infj = self.arr_inf * 1j
            self.arr_complex_nan_infj = np.vstack([self.arr_complex, self.arr_nan_infj])

        self.arr_float_2d = self.arr_float
        self.arr_float1_2d = self.arr_float1

        self.arr_nan_2d = self.arr_nan
        self.arr_float_nan_2d = self.arr_float_nan
        self.arr_float1_nan_2d = self.arr_float1_nan
        self.arr_nan_float1_2d = self.arr_nan_float1

        self.arr_float_1d = self.arr_float[:, 0]
        self.arr_float1_1d = self.arr_float1[:, 0]

        self.arr_nan_1d = self.arr_nan[:, 0]
        self.arr_float_nan_1d = self.arr_float_nan[:, 0]
        self.arr_float1_nan_1d = self.arr_float1_nan[:, 0]
        self.arr_nan_float1_1d = self.arr_nan_float1[:, 0]

    def teardown_method(self):
        nanops._USE_BOTTLENECK = use_bn

    def check_results(self, targ, res, axis, check_dtype=True):
        res = getattr(res, "asm8", res)

        if (
            axis != 0
            and hasattr(targ, "shape")
            and targ.ndim
            and targ.shape != res.shape
        ):
            res = np.split(res, [targ.shape[0]], axis=0)[0]

        try:
            tm.assert_almost_equal(targ, res, check_dtype=check_dtype)
        except AssertionError:
            # handle timedelta dtypes
            if hasattr(targ, "dtype") and targ.dtype == "m8[ns]":
                raise

            # There are sometimes rounding errors with
            # complex and object dtypes.
            # If it isn't one of those, re-raise the error.
            if not hasattr(res, "dtype") or res.dtype.kind not in ["c", "O"]:
                raise
            # convert object dtypes to something that can be split into
            # real and imaginary parts
            if res.dtype.kind == "O":
                if targ.dtype.kind != "O":
                    res = res.astype(targ.dtype)
                else:
                    cast_dtype = "c16" if hasattr(np, "complex128") else "f8"
                    res = res.astype(cast_dtype)
                    targ = targ.astype(cast_dtype)
            # there should never be a case where numpy returns an object
            # but nanops doesn't, so make that an exception
            elif targ.dtype.kind == "O":
                raise
            tm.assert_almost_equal(np.real(targ), np.real(res), check_dtype=check_dtype)
            tm.assert_almost_equal(np.imag(targ), np.imag(res), check_dtype=check_dtype)

    def check_fun_data(
        self,
        testfunc,
        targfunc,
        testar,
        testarval,
        targarval,
        skipna,
        check_dtype=True,
        empty_targfunc=None,
        **kwargs,
    ):
        for axis in [*list(range(targarval.ndim)), None]:
            targartempval = targarval if skipna else testarval
            if skipna and empty_targfunc and isna(targartempval).all():
                targ = empty_targfunc(targartempval, axis=axis, **kwargs)
            else:
                targ = targfunc(targartempval, axis=axis, **kwargs)

            if targartempval.dtype == object and (
                targfunc is np.any or targfunc is np.all
            ):
                # GH#12863 the numpy functions will retain e.g. floatiness
                if isinstance(targ, np.ndarray):
                    targ = targ.astype(bool)
                else:
                    targ = bool(targ)

            if testfunc.__name__ in ["nanargmax", "nanargmin"] and (
                testar.startswith("arr_nan")
                or (testar.endswith("nan") and (not skipna or axis == 1))
            ):
                with pytest.raises(ValueError, match="Encountered .* NA value"):
                    testfunc(testarval, axis=axis, skipna=skipna, **kwargs)
                return
            res = testfunc(testarval, axis=axis, skipna=skipna, **kwargs)

            if (
                isinstance(targ, np.complex128)
                and isinstance(res, float)
                and np.isnan(targ)
                and np.isnan(res)
            ):
                # GH#18463
                targ = res

            self.check_results(targ, res, axis, check_dtype=check_dtype)
            if skipna:
                res = testfunc(testarval, axis=axis, **kwargs)
                self.check_results(targ, res, axis, check_dtype=check_dtype)
            if axis is None:
                res = testfunc(testarval, skipna=skipna, **kwargs)
                self.check_results(targ, res, axis, check_dtype=check_dtype)
            if skipna and axis is None:
                res = testfunc(testarval, **kwargs)
                self.check_results(targ, res, axis, check_dtype=check_dtype)

        if testarval.ndim <= 1:
            return

        # Recurse on lower-dimension
        testarval2 = np.take(testarval, 0, axis=-1)
        targarval2 = np.take(targarval, 0, axis=-1)
        self.check_fun_data(
            testfunc,
            targfunc,
            testar,
            testarval2,
            targarval2,
            skipna=skipna,
            check_dtype=check_dtype,
            empty_targfunc=empty_targfunc,
            **kwargs,
        )

    def check_fun(
        self, testfunc, targfunc, testar, skipna, empty_targfunc=None, **kwargs
    ):
        targar = testar
        if testar.endswith("_nan") and hasattr(self, testar[:-4]):
            targar = testar[:-4]

        testarval = getattr(self, testar)
        targarval = getattr(self, targar)
        self.check_fun_data(
            testfunc,
            targfunc,
            testar,
            testarval,
            targarval,
            skipna=skipna,
            empty_targfunc=empty_targfunc,
            **kwargs,
        )

    def check_funs(
        self,
        testfunc,
        targfunc,
        skipna,
        allow_complex=True,
        allow_all_nan=True,
        allow_date=True,
        allow_tdelta=True,
        allow_obj=True,
        **kwargs,
    ):
        self.check_fun(testfunc, targfunc, "arr_float", skipna, **kwargs)
        self.check_fun(testfunc, targfunc, "arr_float_nan", skipna, **kwargs)
        self.check_fun(testfunc, targfunc, "arr_int", skipna, **kwargs)
        self.check_fun(testfunc, targfunc, "arr_bool", skipna, **kwargs)
        objs = [
            self.arr_float.astype("O"),
            self.arr_int.astype("O"),
            self.arr_bool.astype("O"),
        ]

        if allow_all_nan:
            self.check_fun(testfunc, targfunc, "arr_nan", skipna, **kwargs)

        if allow_complex:
            self.check_fun(testfunc, targfunc, "arr_complex", skipna, **kwargs)
            self.check_fun(testfunc, targfunc, "arr_complex_nan", skipna, **kwargs)
            if allow_all_nan:
                self.check_fun(testfunc, targfunc, "arr_nan_nanj", skipna, **kwargs)
            objs += [self.arr_complex.astype("O")]

        if allow_date:
            targfunc(self.arr_date)
            self.check_fun(testfunc, targfunc, "arr_date", skipna, **kwargs)
            objs += [self.arr_date.astype("O")]

        if allow_tdelta:
            try:
                targfunc(self.arr_tdelta)
            except TypeError:
                pass
            else:
                self.check_fun(testfunc, targfunc, "arr_tdelta", skipna, **kwargs)
                objs += [self.arr_tdelta.astype("O")]

        if allow_obj:
            self.arr_obj = np.vstack(objs)
            # some nanops handle object dtypes better than their numpy
            # counterparts, so the numpy functions need to be given something
            # else
            if allow_obj == "convert":
                targfunc = partial(
                    self._badobj_wrap, func=targfunc, allow_complex=allow_complex
                )
            self.check_fun(testfunc, targfunc, "arr_obj", skipna, **kwargs)

    def _badobj_wrap(self, value, func, allow_complex=True, **kwargs):
        if value.dtype.kind == "O":
            if allow_complex:
                value = value.astype("c16")
            else:
                value = value.astype("f8")
        return func(value, **kwargs)

    @pytest.mark.parametrize(
        "nan_op,np_op", [(nanops.nanany, np.any), (nanops.nanall, np.all)]
    )
    def test_nan_funcs(self, nan_op, np_op, skipna):
        self.check_funs(nan_op, np_op, skipna, allow_all_nan=False, allow_date=False)

    def test_nansum(self, skipna):
        self.check_funs(
            nanops.nansum,
            np.sum,
            skipna,
            allow_date=False,
            check_dtype=False,
            empty_targfunc=np.nansum,
        )

    def test_nanmean(self, skipna):
        self.check_funs(
            nanops.nanmean, np.mean, skipna, allow_obj=False, allow_date=False
        )

    @pytest.mark.filterwarnings("ignore::RuntimeWarning")
    def test_nanmedian(self, skipna):
        self.check_funs(
            nanops.nanmedian,
            np.median,
            skipna,
            allow_complex=False,
            allow_date=False,
            allow_obj="convert",
        )

    @pytest.mark.parametrize("ddof", range(3))
    def test_nanvar(self, ddof, skipna):
        self.check_funs(
            nanops.nanvar,
            np.var,
            skipna,
            allow_complex=False,
            allow_date=False,
            allow_obj="convert",
            ddof=ddof,
        )

    @pytest.mark.parametrize("ddof", range(3))
    def test_nanstd(self, ddof, skipna):
        self.check_funs(
            nanops.nanstd,
            np.std,
            skipna,
            allow_complex=False,
            allow_date=False,
            allow_obj="convert",
            ddof=ddof,
        )

    @pytest.mark.parametrize("ddof", range(3))
    def test_nansem(self, ddof, skipna):
        sp_stats = pytest.importorskip("scipy.stats")

        with np.errstate(invalid="ignore"):
            self.check_funs(
                nanops.nansem,
                sp_stats.sem,
                skipna,
                allow_complex=False,
                allow_date=False,
                allow_tdelta=False,
                allow_obj="convert",
                ddof=ddof,
            )

    @pytest.mark.filterwarnings("ignore::RuntimeWarning")
    @pytest.mark.parametrize(
        "nan_op,np_op", [(nanops.nanmin, np.min), (nanops.nanmax, np.max)]
    )
    def test_nanops_with_warnings(self, nan_op, np_op, skipna):
        self.check_funs(nan_op, np_op, skipna, allow_obj=False)

    def _argminmax_wrap(self, value, axis=None, func=None):
        res = func(value, axis)
        nans = np.min(value, axis)
        nullnan = isna(nans)
        if res.ndim:
            res[nullnan] = -1
        elif (hasattr(nullnan, "all") and nullnan.all()) or (
            not hasattr(nullnan, "all") and nullnan
        ):
            res = -1
        return res

    @pytest.mark.filterwarnings("ignore::RuntimeWarning")
    def test_nanargmax(self, skipna):
        func = partial(self._argminmax_wrap, func=np.argmax)
        self.check_funs(nanops.nanargmax, func, skipna, allow_obj=False)

    @pytest.mark.filterwarnings("ignore::RuntimeWarning")
    def test_nanargmin(self, skipna):
        func = partial(self._argminmax_wrap, func=np.argmin)
        self.check_funs(nanops.nanargmin, func, skipna, allow_obj=False)

    def _skew_kurt_wrap(self, values, axis=None, func=None):
        if not isinstance(values.dtype.type, np.floating):
            values = values.astype("f8")
        result = func(values, axis=axis, bias=False)
        # fix for handling cases where all elements in an axis are the same
        if isinstance(result, np.ndarray):
            result[np.max(values, axis=axis) == np.min(values, axis=axis)] = 0
            return result
        elif np.max(values) == np.min(values):
            return 0.0
        return result

    def test_nanskew(self, skipna):
        sp_stats = pytest.importorskip("scipy.stats")

        func = partial(self._skew_kurt_wrap, func=sp_stats.skew)
        with np.errstate(invalid="ignore"):
            self.check_funs(
                nanops.nanskew,
                func,
                skipna,
                allow_complex=False,
                allow_date=False,
                allow_tdelta=False,
            )

    def test_nankurt(self, skipna):
        sp_stats = pytest.importorskip("scipy.stats")

        func1 = partial(sp_stats.kurtosis, fisher=True)
        func = partial(self._skew_kurt_wrap, func=func1)
        with np.errstate(invalid="ignore"):
            self.check_funs(
                nanops.nankurt,
                func,
                skipna,
                allow_complex=False,
                allow_date=False,
                allow_tdelta=False,
            )

    def test_nanprod(self, skipna):
        self.check_funs(
            nanops.nanprod,
            np.prod,
            skipna,
            allow_date=False,
            allow_tdelta=False,
            empty_targfunc=np.nanprod,
        )

    def check_nancorr_nancov_2d(self, checkfun, targ0, targ1, **kwargs):
        res00 = checkfun(self.arr_float_2d, self.arr_float1_2d, **kwargs)
        res01 = checkfun(
            self.arr_float_2d,
            self.arr_float1_2d,
            min_periods=len(self.arr_float_2d) - 1,
            **kwargs,
        )
        tm.assert_almost_equal(targ0, res00)
        tm.assert_almost_equal(targ0, res01)

        res10 = checkfun(self.arr_float_nan_2d, self.arr_float1_nan_2d, **kwargs)
        res11 = checkfun(
            self.arr_float_nan_2d,
            self.arr_float1_nan_2d,
            min_periods=len(self.arr_float_2d) - 1,
            **kwargs,
        )
        tm.assert_almost_equal(targ1, res10)
        tm.assert_almost_equal(targ1, res11)

        targ2 = np.nan
        res20 = checkfun(self.arr_nan_2d, self.arr_float1_2d, **kwargs)
        res21 = checkfun(self.arr_float_2d, self.arr_nan_2d, **kwargs)
        res22 = checkfun(self.arr_nan_2d, self.arr_nan_2d, **kwargs)
        res23 = checkfun(self.arr_float_nan_2d, self.arr_nan_float1_2d, **kwargs)
        res24 = checkfun(
            self.arr_float_nan_2d,
            self.arr_nan_float1_2d,
            min_periods=len(self.arr_float_2d) - 1,
            **kwargs,
        )
        res25 = checkfun(
            self.arr_float_2d,
            self.arr_float1_2d,
            min_periods=len(self.arr_float_2d) + 1,
            **kwargs,
        )
        tm.assert_almost_equal(targ2, res20)
        tm.assert_almost_equal(targ2, res21)
        tm.assert_almost_equal(targ2, res22)
        tm.assert_almost_equal(targ2, res23)
        tm.assert_almost_equal(targ2, res24)
        tm.assert_almost_equal(targ2, res25)

    def check_nancorr_nancov_1d(self, checkfun, targ0, targ1, **kwargs):
        res00 = checkfun(self.arr_float_1d, self.arr_float1_1d, **kwargs)
        res01 = checkfun(
            self.arr_float_1d,
            self.arr_float1_1d,
            min_periods=len(self.arr_float_1d) - 1,
            **kwargs,
        )
        tm.assert_almost_equal(targ0, res00)
        tm.assert_almost_equal(targ0, res01)

        res10 = checkfun(self.arr_float_nan_1d, self.arr_float1_nan_1d, **kwargs)
        res11 = checkfun(
            self.arr_float_nan_1d,
            self.arr_float1_nan_1d,
            min_periods=len(self.arr_float_1d) - 1,
            **kwargs,
        )
        tm.assert_almost_equal(targ1, res10)
        tm.assert_almost_equal(targ1, res11)

        targ2 = np.nan
        res20 = checkfun(self.arr_nan_1d, self.arr_float1_1d, **kwargs)
        res21 = checkfun(self.arr_float_1d, self.arr_nan_1d, **kwargs)
        res22 = checkfun(self.arr_nan_1d, self.arr_nan_1d, **kwargs)
        res23 = checkfun(self.arr_float_nan_1d, self.arr_nan_float1_1d, **kwargs)
        res24 = checkfun(
            self.arr_float_nan_1d,
            self.arr_nan_float1_1d,
            min_periods=len(self.arr_float_1d) - 1,
            **kwargs,
        )
        res25 = checkfun(
            self.arr_float_1d,
            self.arr_float1_1d,
            min_periods=len(self.arr_float_1d) + 1,
            **kwargs,
        )
        tm.assert_almost_equal(targ2, res20)
        tm.assert_almost_equal(targ2, res21)
        tm.assert_almost_equal(targ2, res22)
        tm.assert_almost_equal(targ2, res23)
        tm.assert_almost_equal(targ2, res24)
        tm.assert_almost_equal(targ2, res25)

    def test_nancorr(self):
        targ0 = np.corrcoef(self.arr_float_2d, self.arr_float1_2d)[0, 1]
        targ1 = np.corrcoef(self.arr_float_2d.flat, self.arr_float1_2d.flat)[0, 1]
        self.check_nancorr_nancov_2d(nanops.nancorr, targ0, targ1)
        targ0 = np.corrcoef(self.arr_float_1d, self.arr_float1_1d)[0, 1]
        targ1 = np.corrcoef(self.arr_float_1d.flat, self.arr_float1_1d.flat)[0, 1]
        self.check_nancorr_nancov_1d(nanops.nancorr, targ0, targ1, method="pearson")

    def test_nancorr_pearson(self):
        targ0 = np.corrcoef(self.arr_float_2d, self.arr_float1_2d)[0, 1]
        targ1 = np.corrcoef(self.arr_float_2d.flat, self.arr_float1_2d.flat)[0, 1]
        self.check_nancorr_nancov_2d(nanops.nancorr, targ0, targ1, method="pearson")
        targ0 = np.corrcoef(self.arr_float_1d, self.arr_float1_1d)[0, 1]
        targ1 = np.corrcoef(self.arr_float_1d.flat, self.arr_float1_1d.flat)[0, 1]
        self.check_nancorr_nancov_1d(nanops.nancorr, targ0, targ1, method="pearson")

    def test_nancorr_kendall(self):
        sp_stats = pytest.importorskip("scipy.stats")

        targ0 = sp_stats.kendalltau(self.arr_float_2d, self.arr_float1_2d)[0]
        targ1 = sp_stats.kendalltau(self.arr_float_2d.flat, self.arr_float1_2d.flat)[0]
        self.check_nancorr_nancov_2d(nanops.nancorr, targ0, targ1, method="kendall")
        targ0 = sp_stats.kendalltau(self.arr_float_1d, self.arr_float1_1d)[0]
        targ1 = sp_stats.kendalltau(self.arr_float_1d.flat, self.arr_float1_1d.flat)[0]
        self.check_nancorr_nancov_1d(nanops.nancorr, targ0, targ1, method="kendall")

    def test_nancorr_spearman(self):
        sp_stats = pytest.importorskip("scipy.stats")

        targ0 = sp_stats.spearmanr(self.arr_float_2d, self.arr_float1_2d)[0]
        targ1 = sp_stats.spearmanr(self.arr_float_2d.flat, self.arr_float1_2d.flat)[0]
        self.check_nancorr_nancov_2d(nanops.nancorr, targ0, targ1, method="spearman")
        targ0 = sp_stats.spearmanr(self.arr_float_1d, self.arr_float1_1d)[0]
        targ1 = sp_stats.spearmanr(self.arr_float_1d.flat, self.arr_float1_1d.flat)[0]
        self.check_nancorr_nancov_1d(nanops.nancorr, targ0, targ1, method="spearman")

    def test_invalid_method(self):
        pytest.importorskip("scipy")
        targ0 = np.corrcoef(self.arr_float_2d, self.arr_float1_2d)[0, 1]
        targ1 = np.corrcoef(self.arr_float_2d.flat, self.arr_float1_2d.flat)[0, 1]
        msg = "Unknown method 'foo', expected one of 'kendall', 'spearman'"
        with pytest.raises(ValueError, match=msg):
            self.check_nancorr_nancov_1d(nanops.nancorr, targ0, targ1, method="foo")

    def test_nancov(self):
        targ0 = np.cov(self.arr_float_2d, self.arr_float1_2d)[0, 1]
        targ1 = np.cov(self.arr_float_2d.flat, self.arr_float1_2d.flat)[0, 1]
        self.check_nancorr_nancov_2d(nanops.nancov, targ0, targ1)
        targ0 = np.cov(self.arr_float_1d, self.arr_float1_1d)[0, 1]
        targ1 = np.cov(self.arr_float_1d.flat, self.arr_float1_1d.flat)[0, 1]
        self.check_nancorr_nancov_1d(nanops.nancov, targ0, targ1)


@pytest.mark.parametrize(
    "arr, correct",
    [
        ("arr_complex", False),
        ("arr_int", False),
        ("arr_bool", False),
        ("arr_str", False),
        ("arr_utf", False),
        ("arr_complex_nan", False),
        ("arr_nan_nanj", False),
        ("arr_nan_infj", True),
        ("arr_complex_nan_infj", True),
    ],
)
def test_has_infs_non_float(request, arr, correct, disable_bottleneck):
    val = request.getfixturevalue(arr)
    while getattr(val, "ndim", True):
        res0 = nanops._has_infs(val)
        if correct:
            assert res0
        else:
            assert not res0

        if not hasattr(val, "ndim"):
            break

        # Reduce dimension for next step in the loop
        val = np.take(val, 0, axis=-1)


@pytest.mark.parametrize(
    "arr, correct",
    [
        ("arr_float", False),
        ("arr_nan", False),
        ("arr_float_nan", False),
        ("arr_nan_nan", False),
        ("arr_float_inf", True),
        ("arr_inf", True),
        ("arr_nan_inf", True),
        ("arr_float_nan_inf", True),
        ("arr_nan_nan_inf", True),
    ],
)
@pytest.mark.parametrize("astype", [None, "f4", "f2"])
def test_has_infs_floats(request, arr, correct, astype, disable_bottleneck):
    val = request.getfixturevalue(arr)
    if astype is not None:
        val = val.astype(astype)
    while getattr(val, "ndim", True):
        res0 = nanops._has_infs(val)
        if correct:
            assert res0
        else:
            assert not res0

        if not hasattr(val, "ndim"):
            break

        # Reduce dimension for next step in the loop
        val = np.take(val, 0, axis=-1)


@pytest.mark.parametrize(
    "fixture", ["arr_float", "arr_complex", "arr_int", "arr_bool", "arr_str", "arr_utf"]
)
def test_bn_ok_dtype(fixture, request, disable_bottleneck):
    obj = request.getfixturevalue(fixture)
    assert nanops._bn_ok_dtype(obj.dtype, "test")


@pytest.mark.parametrize(
    "fixture",
    [
        "arr_date",
        "arr_tdelta",
        "arr_obj",
    ],
)
def test_bn_not_ok_dtype(fixture, request, disable_bottleneck):
    obj = request.getfixturevalue(fixture)
    assert not nanops._bn_ok_dtype(obj.dtype, "test")


class TestEnsureNumeric:
    def test_numeric_values(self):
        # Test integer
        assert nanops._ensure_numeric(1) == 1

        # Test float
        assert nanops._ensure_numeric(1.1) == 1.1

        # Test complex
        assert nanops._ensure_numeric(1 + 2j) == 1 + 2j

    def test_ndarray(self):
        # Test numeric ndarray
        values = np.array([1, 2, 3])
        assert np.allclose(nanops._ensure_numeric(values), values)

        # Test object ndarray
        o_values = values.astype(object)
        assert np.allclose(nanops._ensure_numeric(o_values), values)

        # Test convertible string ndarray
        s_values = np.array(["1", "2", "3"], dtype=object)
        msg = r"Could not convert \['1' '2' '3'\] to numeric"
        with pytest.raises(TypeError, match=msg):
            nanops._ensure_numeric(s_values)

        # Test non-convertible string ndarray
        s_values = np.array(["foo", "bar", "baz"], dtype=object)
        msg = r"Could not convert .* to numeric"
        with pytest.raises(TypeError, match=msg):
            nanops._ensure_numeric(s_values)

    def test_convertable_values(self):
        with pytest.raises(TypeError, match="Could not convert string '1' to numeric"):
            nanops._ensure_numeric("1")
        with pytest.raises(
            TypeError, match="Could not convert string '1.1' to numeric"
        ):
            nanops._ensure_numeric("1.1")
        with pytest.raises(
            TypeError, match=r"Could not convert string '1\+1j' to numeric"
        ):
            nanops._ensure_numeric("1+1j")

    def test_non_convertable_values(self):
        msg = "Could not convert string 'foo' to numeric"
        with pytest.raises(TypeError, match=msg):
            nanops._ensure_numeric("foo")

        # with the wrong type, python raises TypeError for us
        msg = "argument must be a string or a number"
        with pytest.raises(TypeError, match=msg):
            nanops._ensure_numeric({})
        with pytest.raises(TypeError, match=msg):
            nanops._ensure_numeric([])


class TestNanvarFixedValues:
    # xref GH10242
    # Samples from a normal distribution.
    @pytest.fixture
    def variance(self):
        return 3.0

    @pytest.fixture
    def samples(self, variance):
        return self.prng.normal(scale=variance**0.5, size=100000)

    def test_nanvar_all_finite(self, samples, variance):
        actual_variance = nanops.nanvar(samples)
        tm.assert_almost_equal(actual_variance, variance, rtol=1e-2)

    def test_nanvar_nans(self, samples, variance):
        samples_test = np.nan * np.ones(2 * samples.shape[0])
        samples_test[::2] = samples

        actual_variance = nanops.nanvar(samples_test, skipna=True)
        tm.assert_almost_equal(actual_variance, variance, rtol=1e-2)

        actual_variance = nanops.nanvar(samples_test, skipna=False)
        tm.assert_almost_equal(actual_variance, np.nan, rtol=1e-2)

    def test_nanstd_nans(self, samples, variance):
        samples_test = np.nan * np.ones(2 * samples.shape[0])
        samples_test[::2] = samples

        actual_std = nanops.nanstd(samples_test, skipna=True)
        tm.assert_almost_equal(actual_std, variance**0.5, rtol=1e-2)

        actual_std = nanops.nanvar(samples_test, skipna=False)
        tm.assert_almost_equal(actual_std, np.nan, rtol=1e-2)

    def test_nanvar_axis(self, samples, variance):
        # Generate some sample data.
        samples_unif = self.prng.uniform(size=samples.shape[0])
        samples = np.vstack([samples, samples_unif])

        actual_variance = nanops.nanvar(samples, axis=1)
        tm.assert_almost_equal(
            actual_variance, np.array([variance, 1.0 / 12]), rtol=1e-2
        )

    def test_nanvar_ddof(self):
        n = 5
        samples = self.prng.uniform(size=(10000, n + 1))
        samples[:, -1] = np.nan  # Force use of our own algorithm.

        variance_0 = nanops.nanvar(samples, axis=1, skipna=True, ddof=0).mean()
        variance_1 = nanops.nanvar(samples, axis=1, skipna=True, ddof=1).mean()
        variance_2 = nanops.nanvar(samples, axis=1, skipna=True, ddof=2).mean()

        # The unbiased estimate.
        var = 1.0 / 12
        tm.assert_almost_equal(variance_1, var, rtol=1e-2)

        # The underestimated variance.
        tm.assert_almost_equal(variance_0, (n - 1.0) / n * var, rtol=1e-2)

        # The overestimated variance.
        tm.assert_almost_equal(variance_2, (n - 1.0) / (n - 2.0) * var, rtol=1e-2)

    @pytest.mark.parametrize("axis", range(2))
    @pytest.mark.parametrize("ddof", range(3))
    def test_ground_truth(self, axis, ddof):
        # Test against values that were precomputed with Numpy.
        samples = np.empty((4, 4))
        samples[:3, :3] = np.array(
            [
                [0.97303362, 0.21869576, 0.55560287],
                [0.72980153, 0.03109364, 0.99155171],
                [0.09317602, 0.60078248, 0.15871292],
            ]
        )
        samples[3] = samples[:, 3] = np.nan

        # Actual variances along axis=0, 1 for ddof=0, 1, 2
        variance = np.array(
            [
                [
                    [0.13762259, 0.05619224, 0.11568816],
                    [0.20643388, 0.08428837, 0.17353224],
                    [0.41286776, 0.16857673, 0.34706449],
                ],
                [
                    [0.09519783, 0.16435395, 0.05082054],
                    [0.14279674, 0.24653093, 0.07623082],
                    [0.28559348, 0.49306186, 0.15246163],
                ],
            ]
        )

        # Test nanvar.
        var = nanops.nanvar(samples, skipna=True, axis=axis, ddof=ddof)
        tm.assert_almost_equal(var[:3], variance[axis, ddof])
        assert np.isnan(var[3])

        # Test nanstd.
        std = nanops.nanstd(samples, skipna=True, axis=axis, ddof=ddof)
        tm.assert_almost_equal(std[:3], variance[axis, ddof] ** 0.5)
        assert np.isnan(std[3])

    @pytest.mark.parametrize("ddof", range(3))
    @pytest.mark.parametrize("axis", [0, 1, None])
    @pytest.mark.parametrize("method", ["var", "std", "sem"])
    def test_complex_nanvar(self, ddof, axis, method):
        arr = self.prng.standard_normal((5, 4)) + self.prng.standard_normal((5, 4)) * 1j
        nanops_method = getattr(nanops, f"nan{method}")
        if method in {"var", "std"}:
            comparator_method = getattr(np, method)
        elif method == "sem":
            comparator_method = pytest.importorskip("scipy.stats").sem
        result = nanops_method(arr, axis=axis, ddof=ddof)
        expected = comparator_method(arr, axis=axis, ddof=ddof)
        tm.assert_almost_equal(result, expected)

    @pytest.mark.parametrize("ddof", range(3))
    def test_nanstd_roundoff(self, ddof):
        # Regression test for GH 10242 (test data taken from GH 10489). Ensure
        # that variance is stable.
        data = Series(766897346 * np.ones(10))
        result = data.std(ddof=ddof)
        assert result == 0.0

    @property
    def prng(self):
        return np.random.default_rng(2)


class TestNanskewFixedValues:
    # xref GH 11974
    # Test data + skewness value (computed with scipy.stats.skew)
    @pytest.fixture
    def samples(self):
        return np.sin(np.linspace(0, 1, 200))

    @pytest.fixture
    def actual_skew(self):
        return -0.1875895205961754

    @pytest.mark.parametrize("val", [3075.2, 3075.3, 3075.5])
    def test_constant_series(self, val):
        # xref GH 11974
        data = val * np.ones(300)
        skew = nanops.nanskew(data)
        assert skew == 0.0

    def test_all_finite(self):
        alpha, beta = 0.3, 0.1
        left_tailed = self.prng.beta(alpha, beta, size=100)
        assert nanops.nanskew(left_tailed) < 0

        alpha, beta = 0.1, 0.3
        right_tailed = self.prng.beta(alpha, beta, size=100)
        assert nanops.nanskew(right_tailed) > 0

    def test_ground_truth(self, samples, actual_skew):
        skew = nanops.nanskew(samples)
        tm.assert_almost_equal(skew, actual_skew)

    def test_axis(self, samples, actual_skew):
        samples = np.vstack([samples, np.nan * np.ones(len(samples))])
        skew = nanops.nanskew(samples, axis=1)
        tm.assert_almost_equal(skew, np.array([actual_skew, np.nan]))

    def test_nans(self, samples):
        samples = np.hstack([samples, np.nan])
        skew = nanops.nanskew(samples, skipna=False)
        assert np.isnan(skew)

    def test_nans_skipna(self, samples, actual_skew):
        samples = np.hstack([samples, np.nan])
        skew = nanops.nanskew(samples, skipna=True)
        tm.assert_almost_equal(skew, actual_skew)

    @pytest.mark.parametrize(
        "initial_data, nobs",
        [
            ([-2.05191341e-05, -4.10391103e-05], 27),
            ([-2.05191341e-10, -4.10391103e-10], 27),
            ([-2.05191341e-05, -4.10391103e-05], 10_000),
            ([-2.05191341e-10, -4.10391103e-10], 10_000),
        ],
    )
    def test_low_variance(self, initial_data, nobs):
        st = pytest.importorskip("scipy.stats")
        data = np.zeros((nobs,), dtype=np.float64)
        data[: len(initial_data)] = initial_data
        skew = nanops.nanskew(data)
        expected = st.skew(data, bias=False)
        tm.assert_almost_equal(skew, expected)

    @property
    def prng(self):
        return np.random.default_rng(2)


class TestNankurtFixedValues:
    # xref GH 11974
    # Test data + kurtosis value (computed with scipy.stats.kurtosis)
    @pytest.fixture
    def samples(self):
        return np.sin(np.linspace(0, 1, 200))

    @pytest.fixture
    def actual_kurt(self):
        return -1.2058303433799713

    @pytest.mark.parametrize("val", [3075.2, 3075.3, 3075.5])
    def test_constant_series(self, val):
        # xref GH 11974
        data = val * np.ones(300)
        kurt = nanops.nankurt(data)
        tm.assert_equal(kurt, 0.0)

    def test_all_finite(self):
        alpha, beta = 0.3, 0.1
        left_tailed = self.prng.beta(alpha, beta, size=100)
        assert nanops.nankurt(left_tailed) < 2

        alpha, beta = 0.1, 0.3
        right_tailed = self.prng.beta(alpha, beta, size=100)
        assert nanops.nankurt(right_tailed) < 0

    def test_ground_truth(self, samples, actual_kurt):
        kurt = nanops.nankurt(samples)
        tm.assert_almost_equal(kurt, actual_kurt)

    def test_axis(self, samples, actual_kurt):
        samples = np.vstack([samples, np.nan * np.ones(len(samples))])
        kurt = nanops.nankurt(samples, axis=1)
        tm.assert_almost_equal(kurt, np.array([actual_kurt, np.nan]))

    def test_nans(self, samples):
        samples = np.hstack([samples, np.nan])
        kurt = nanops.nankurt(samples, skipna=False)
        assert np.isnan(kurt)

    def test_nans_skipna(self, samples, actual_kurt):
        samples = np.hstack([samples, np.nan])
        kurt = nanops.nankurt(samples, skipna=True)
        tm.assert_almost_equal(kurt, actual_kurt)

    @pytest.mark.parametrize(
        "initial_data, nobs",
        [
            ([-2.05191341e-05, -4.10391103e-05], 27),
            ([-2.05191341e-10, -4.10391103e-10], 27),
            ([-2.05191341e-05, -4.10391103e-05], 10_000),
            ([-2.05191341e-10, -4.10391103e-10], 10_000),
        ],
    )
    def test_low_variance(self, initial_data, nobs):
        # GH#57972
        st = pytest.importorskip("scipy.stats")
        data = np.zeros((nobs,), dtype=np.float64)
        data[: len(initial_data)] = initial_data
        kurt = nanops.nankurt(data)
        expected = st.kurtosis(data, bias=False)
        tm.assert_almost_equal(kurt, expected)

    @property
    def prng(self):
        return np.random.default_rng(2)


class TestDatetime64NaNOps:
    # Enabling mean changes the behavior of DataFrame.mean
    # See https://github.com/pandas-dev/pandas/issues/24752
    def test_nanmean(self, unit):
        dti = pd.date_range("2016-01-01", periods=3).as_unit(unit)
        expected = dti[1]

        for obj in [dti, dti._data]:
            result = nanops.nanmean(obj)
            assert result == expected

        dti2 = dti.insert(1, pd.NaT)

        for obj in [dti2, dti2._data]:
            result = nanops.nanmean(obj)
            assert result == expected

    @pytest.mark.parametrize("constructor", ["M8", "m8"])
    def test_nanmean_skipna_false(self, constructor, unit):
        dtype = f"{constructor}[{unit}]"
        arr = np.arange(12).astype(np.int64).view(dtype).reshape(4, 3)

        arr[-1, -1] = "NaT"

        result = nanops.nanmean(arr, skipna=False)
        assert np.isnat(result)
        assert result.dtype == dtype

        result = nanops.nanmean(arr, axis=0, skipna=False)
        expected = np.array([4, 5, "NaT"], dtype=arr.dtype)
        tm.assert_numpy_array_equal(result, expected)

        result = nanops.nanmean(arr, axis=1, skipna=False)
        expected = np.array([arr[0, 1], arr[1, 1], arr[2, 1], arr[-1, -1]])
        tm.assert_numpy_array_equal(result, expected)


def test_use_bottleneck():
    if nanops._BOTTLENECK_INSTALLED:
        with pd.option_context("use_bottleneck", True):
            assert pd.get_option("use_bottleneck")

        with pd.option_context("use_bottleneck", False):
            assert not pd.get_option("use_bottleneck")


@pytest.mark.parametrize(
    "numpy_op, expected",
    [
        (np.sum, 10),
        (np.nansum, 10),
        (np.mean, 2.5),
        (np.nanmean, 2.5),
        (np.median, 2.5),
        (np.nanmedian, 2.5),
        (np.min, 1),
        (np.max, 4),
        (np.nanmin, 1),
        (np.nanmax, 4),
    ],
)
def test_numpy_ops(numpy_op, expected):
    # GH8383
    result = numpy_op(Series([1, 2, 3, 4]))
    assert result == expected


@pytest.mark.parametrize(
    "operation",
    [
        nanops.nanany,
        nanops.nanall,
        nanops.nansum,
        nanops.nanmean,
        nanops.nanmedian,
        nanops.nanstd,
        nanops.nanvar,
        nanops.nansem,
        nanops.nanargmax,
        nanops.nanargmin,
        nanops.nanmax,
        nanops.nanmin,
        nanops.nanskew,
        nanops.nankurt,
        nanops.nanprod,
    ],
)
def test_nanops_independent_of_mask_param(operation):
    # GH22764
    ser = Series([1, 2, np.nan, 3, np.nan, 4])
    mask = ser.isna()
    median_expected = operation(ser._values)
    median_result = operation(ser._values, mask=mask)
    assert median_expected == median_result


@pytest.mark.parametrize("min_count", [-1, 0])
def test_check_below_min_count_negative_or_zero_min_count(min_count):
    # GH35227
    result = nanops.check_below_min_count((21, 37), None, min_count)
    expected_result = False
    assert result == expected_result


@pytest.mark.parametrize(
    "mask", [None, np.array([False, False, True]), np.array([True] + 9 * [False])]
)
@pytest.mark.parametrize("min_count, expected_result", [(1, False), (101, True)])
def test_check_below_min_count_positive_min_count(mask, min_count, expected_result):
    # GH35227
    shape = (10, 10)
    result = nanops.check_below_min_count(shape, mask, min_count)
    assert result == expected_result


@td.skip_if_windows
@td.skip_if_32bit
@pytest.mark.parametrize("min_count, expected_result", [(1, False), (2812191852, True)])
def test_check_below_min_count_large_shape(min_count, expected_result):
    # GH35227 large shape used to show that the issue is fixed
    shape = (2244367, 1253)
    result = nanops.check_below_min_count(shape, mask=None, min_count=min_count)
    assert result == expected_result


@pytest.mark.parametrize("func", ["nanmean", "nansum"])
def test_check_bottleneck_disallow(any_real_numpy_dtype, func):
    # GH 42878 bottleneck sometimes produces unreliable results for mean and sum
    assert not nanops._bn_ok_dtype(np.dtype(any_real_numpy_dtype).type, func)


@pytest.mark.parametrize("val", [2**55, -(2**55), 20150515061816532])
def test_nanmean_overflow(disable_bottleneck, val, using_python_scalars):
    # GH 10155
    # In the previous implementation mean can overflow for int dtypes, it
    # is now consistent with numpy

    ser = Series(val, index=range(500), dtype=np.int64)
    result = ser.mean()
    assert result == val
    if using_python_scalars:
        assert type(result) == float
    else:
        np_result = ser.values.mean()
        assert result == np_result
        assert result.dtype == np.float64


@pytest.mark.parametrize(
    "dtype",
    [
        np.int16,
        np.int32,
        np.int64,
        np.float32,
        np.float64,
        getattr(np, "float128", None),
    ],
)
@pytest.mark.parametrize("method", ["mean", "std", "var", "skew", "kurt", "min", "max"])
def test_returned_dtype(disable_bottleneck, dtype, method, using_python_scalars):
    if dtype is None:
        pytest.skip("np.float128 not available")

    ser = Series(range(10), dtype=dtype)
    result = getattr(ser, method)()
    if using_python_scalars:
        if is_integer_dtype(dtype) and method in ["min", "max"]:
            assert isinstance(result, int)
        else:
            assert type(result) == float
    elif is_integer_dtype(dtype) and method not in ["min", "max"]:
        assert result.dtype == np.float64
    else:
        assert result.dtype == dtype
