test_sorting.py

from collections import defaultdict
from datetime import datetime
from itertools import product

import numpy as np
import pytest

from pandas import DataFrame, MultiIndex, Series, array, concat, merge
import pandas._testing as tm
from pandas.core.algorithms import safe_sort
import pandas.core.common as com
from pandas.core.sorting import (
    decons_group_index,
    get_group_index,
    is_int64_overflow_possible,
    lexsort_indexer,
    nargsort,
)


class TestSorting:
    @pytest.mark.slow
    def test_int64_overflow(self):

        B = np.concatenate((np.arange(1000), np.arange(1000), np.arange(500)))
        A = np.arange(2500)
        df = DataFrame(
            {
                "A": A,
                "B": B,
                "C": A,
                "D": B,
                "E": A,
                "F": B,
                "G": A,
                "H": B,
                "values": np.random.randn(2500),
            }
        )

        lg = df.groupby(["A", "B", "C", "D", "E", "F", "G", "H"])
        rg = df.groupby(["H", "G", "F", "E", "D", "C", "B", "A"])

        left = lg.sum()["values"]
        right = rg.sum()["values"]

        exp_index, _ = left.index.sortlevel()
        tm.assert_index_equal(left.index, exp_index)

        exp_index, _ = right.index.sortlevel(0)
        tm.assert_index_equal(right.index, exp_index)

        tups = list(map(tuple, df[["A", "B", "C", "D", "E", "F", "G", "H"]].values))
        tups = com.asarray_tuplesafe(tups)

        expected = df.groupby(tups).sum()["values"]

        for k, v in expected.items():
            assert left[k] == right[k[::-1]]
            assert left[k] == v
        assert len(left) == len(right)

    @pytest.mark.arm_slow
    def test_int64_overflow_moar(self):

        # GH9096
        values = range(55109)
        data = DataFrame.from_dict({"a": values, "b": values, "c": values, "d": values})
        grouped = data.groupby(["a", "b", "c", "d"])
        assert len(grouped) == len(values)

        arr = np.random.randint(-1 << 12, 1 << 12, (1 << 15, 5))
        i = np.random.choice(len(arr), len(arr) * 4)
        arr = np.vstack((arr, arr[i]))  # add sume duplicate rows

        i = np.random.permutation(len(arr))
        arr = arr[i]  # shuffle rows

        df = DataFrame(arr, columns=list("abcde"))
        df["jim"], df["joe"] = np.random.randn(2, len(df)) * 10
        gr = df.groupby(list("abcde"))

        # verify this is testing what it is supposed to test!
        assert is_int64_overflow_possible(gr.grouper.shape)

        # manually compute groupings
        jim, joe = defaultdict(list), defaultdict(list)
        for key, a, b in zip(map(tuple, arr), df["jim"], df["joe"]):
            jim[key].append(a)
            joe[key].append(b)

        assert len(gr) == len(jim)
        mi = MultiIndex.from_tuples(jim.keys(), names=list("abcde"))

        def aggr(func):
            f = lambda a: np.fromiter(map(func, a), dtype="f8")
            arr = np.vstack((f(jim.values()), f(joe.values()))).T
            res = DataFrame(arr, columns=["jim", "joe"], index=mi)
            return res.sort_index()

        tm.assert_frame_equal(gr.mean(), aggr(np.mean))
        tm.assert_frame_equal(gr.median(), aggr(np.median))

    def test_lexsort_indexer(self):
        keys = [[np.nan] * 5 + list(range(100)) + [np.nan] * 5]
        # orders=True, na_position='last'
        result = lexsort_indexer(keys, orders=True, na_position="last")
        exp = list(range(5, 105)) + list(range(5)) + list(range(105, 110))
        tm.assert_numpy_array_equal(result, np.array(exp, dtype=np.intp))

        # orders=True, na_position='first'
        result = lexsort_indexer(keys, orders=True, na_position="first")
        exp = list(range(5)) + list(range(105, 110)) + list(range(5, 105))
        tm.assert_numpy_array_equal(result, np.array(exp, dtype=np.intp))

        # orders=False, na_position='last'
        result = lexsort_indexer(keys, orders=False, na_position="last")
        exp = list(range(104, 4, -1)) + list(range(5)) + list(range(105, 110))
        tm.assert_numpy_array_equal(result, np.array(exp, dtype=np.intp))

        # orders=False, na_position='first'
        result = lexsort_indexer(keys, orders=False, na_position="first")
        exp = list(range(5)) + list(range(105, 110)) + list(range(104, 4, -1))
        tm.assert_numpy_array_equal(result, np.array(exp, dtype=np.intp))

    def test_nargsort(self):
        # np.argsort(items) places NaNs last
        items = [np.nan] * 5 + list(range(100)) + [np.nan] * 5
        # np.argsort(items2) may not place NaNs first
        items2 = np.array(items, dtype="O")

        # mergesort is the most difficult to get right because we want it to be
        # stable.

        # According to numpy/core/tests/test_multiarray, """The number of
        # sorted items must be greater than ~50 to check the actual algorithm
        # because quick and merge sort fall over to insertion sort for small
        # arrays."""

        # mergesort, ascending=True, na_position='last'
        result = nargsort(items, kind="mergesort", ascending=True, na_position="last")
        exp = list(range(5, 105)) + list(range(5)) + list(range(105, 110))
        tm.assert_numpy_array_equal(result, np.array(exp), check_dtype=False)

        # mergesort, ascending=True, na_position='first'
        result = nargsort(items, kind="mergesort", ascending=True, na_position="first")
        exp = list(range(5)) + list(range(105, 110)) + list(range(5, 105))
        tm.assert_numpy_array_equal(result, np.array(exp), check_dtype=False)

        # mergesort, ascending=False, na_position='last'
        result = nargsort(items, kind="mergesort", ascending=False, na_position="last")
        exp = list(range(104, 4, -1)) + list(range(5)) + list(range(105, 110))
        tm.assert_numpy_array_equal(result, np.array(exp), check_dtype=False)

        # mergesort, ascending=False, na_position='first'
        result = nargsort(items, kind="mergesort", ascending=False, na_position="first")
        exp = list(range(5)) + list(range(105, 110)) + list(range(104, 4, -1))
        tm.assert_numpy_array_equal(result, np.array(exp), check_dtype=False)

        # mergesort, ascending=True, na_position='last'
        result = nargsort(items2, kind="mergesort", ascending=True, na_position="last")
        exp = list(range(5, 105)) + list(range(5)) + list(range(105, 110))
        tm.assert_numpy_array_equal(result, np.array(exp), check_dtype=False)

        # mergesort, ascending=True, na_position='first'
        result = nargsort(items2, kind="mergesort", ascending=True, na_position="first")
        exp = list(range(5)) + list(range(105, 110)) + list(range(5, 105))
        tm.assert_numpy_array_equal(result, np.array(exp), check_dtype=False)

        # mergesort, ascending=False, na_position='last'
        result = nargsort(items2, kind="mergesort", ascending=False, na_position="last")
        exp = list(range(104, 4, -1)) + list(range(5)) + list(range(105, 110))
        tm.assert_numpy_array_equal(result, np.array(exp), check_dtype=False)

        # mergesort, ascending=False, na_position='first'
        result = nargsort(
            items2, kind="mergesort", ascending=False, na_position="first"
        )
        exp = list(range(5)) + list(range(105, 110)) + list(range(104, 4, -1))
        tm.assert_numpy_array_equal(result, np.array(exp), check_dtype=False)


class TestMerge:
    @pytest.mark.slow
    def test_int64_overflow_issues(self):

        # #2690, combinatorial explosion
        df1 = DataFrame(np.random.randn(1000, 7), columns=list("ABCDEF") + ["G1"])
        df2 = DataFrame(np.random.randn(1000, 7), columns=list("ABCDEF") + ["G2"])

        # it works!
        result = merge(df1, df2, how="outer")
        assert len(result) == 2000

        low, high, n = -1 << 10, 1 << 10, 1 << 20
        left = DataFrame(np.random.randint(low, high, (n, 7)), columns=list("ABCDEFG"))
        left["left"] = left.sum(axis=1)

        # one-2-one match
        i = np.random.permutation(len(left))
        right = left.iloc[i].copy()
        right.columns = right.columns[:-1].tolist() + ["right"]
        right.index = np.arange(len(right))
        right["right"] *= -1

        out = merge(left, right, how="outer")
        assert len(out) == len(left)
        tm.assert_series_equal(out["left"], -out["right"], check_names=False)
        result = out.iloc[:, :-2].sum(axis=1)
        tm.assert_series_equal(out["left"], result, check_names=False)
        assert result.name is None

        out.sort_values(out.columns.tolist(), inplace=True)
        out.index = np.arange(len(out))
        for how in ["left", "right", "outer", "inner"]:
            tm.assert_frame_equal(out, merge(left, right, how=how, sort=True))

        # check that left merge w/ sort=False maintains left frame order
        out = merge(left, right, how="left", sort=False)
        tm.assert_frame_equal(left, out[left.columns.tolist()])

        out = merge(right, left, how="left", sort=False)
        tm.assert_frame_equal(right, out[right.columns.tolist()])

        # one-2-many/none match
        n = 1 << 11
        left = DataFrame(
            np.random.randint(low, high, (n, 7)).astype("int64"),
            columns=list("ABCDEFG"),
        )

        # confirm that this is checking what it is supposed to check
        shape = left.apply(Series.nunique).values
        assert is_int64_overflow_possible(shape)

        # add duplicates to left frame
        left = concat([left, left], ignore_index=True)

        right = DataFrame(
            np.random.randint(low, high, (n // 2, 7)).astype("int64"),
            columns=list("ABCDEFG"),
        )

        # add duplicates & overlap with left to the right frame
        i = np.random.choice(len(left), n)
        right = concat([right, right, left.iloc[i]], ignore_index=True)

        left["left"] = np.random.randn(len(left))
        right["right"] = np.random.randn(len(right))

        # shuffle left & right frames
        i = np.random.permutation(len(left))
        left = left.iloc[i].copy()
        left.index = np.arange(len(left))

        i = np.random.permutation(len(right))
        right = right.iloc[i].copy()
        right.index = np.arange(len(right))

        # manually compute outer merge
        ldict, rdict = defaultdict(list), defaultdict(list)

        for idx, row in left.set_index(list("ABCDEFG")).iterrows():
            ldict[idx].append(row["left"])

        for idx, row in right.set_index(list("ABCDEFG")).iterrows():
            rdict[idx].append(row["right"])

        vals = []
        for k, lval in ldict.items():
            rval = rdict.get(k, [np.nan])
            for lv, rv in product(lval, rval):
                vals.append(k + tuple([lv, rv]))

        for k, rval in rdict.items():
            if k not in ldict:
                for rv in rval:
                    vals.append(k + tuple([np.nan, rv]))

        def align(df):
            df = df.sort_values(df.columns.tolist())
            df.index = np.arange(len(df))
            return df

        def verify_order(df):
            kcols = list("ABCDEFG")
            tm.assert_frame_equal(
                df[kcols].copy(), df[kcols].sort_values(kcols, kind="mergesort")
            )

        out = DataFrame(vals, columns=list("ABCDEFG") + ["left", "right"])
        out = align(out)

        jmask = {
            "left": out["left"].notna(),
            "right": out["right"].notna(),
            "inner": out["left"].notna() & out["right"].notna(),
            "outer": np.ones(len(out), dtype="bool"),
        }

        for how in ["left", "right", "outer", "inner"]:
            mask = jmask[how]
            frame = align(out[mask].copy())
            assert mask.all() ^ mask.any() or how == "outer"

            for sort in [False, True]:
                res = merge(left, right, how=how, sort=sort)
                if sort:
                    verify_order(res)

                # as in GH9092 dtypes break with outer/right join
                tm.assert_frame_equal(
                    frame, align(res), check_dtype=how not in ("right", "outer")
                )


def test_decons():
    def testit(codes_list, shape):
        group_index = get_group_index(codes_list, shape, sort=True, xnull=True)
        codes_list2 = decons_group_index(group_index, shape)

        for a, b in zip(codes_list, codes_list2):
            tm.assert_numpy_array_equal(a, b)

    shape = (4, 5, 6)
    codes_list = [
        np.tile([0, 1, 2, 3, 0, 1, 2, 3], 100).astype(np.int64),
        np.tile([0, 2, 4, 3, 0, 1, 2, 3], 100).astype(np.int64),
        np.tile([5, 1, 0, 2, 3, 0, 5, 4], 100).astype(np.int64),
    ]
    testit(codes_list, shape)

    shape = (10000, 10000)
    codes_list = [
        np.tile(np.arange(10000, dtype=np.int64), 5),
        np.tile(np.arange(10000, dtype=np.int64), 5),
    ]
    testit(codes_list, shape)


class TestSafeSort:
    def test_basic_sort(self):
        values = [3, 1, 2, 0, 4]
        result = safe_sort(values)
        expected = np.array([0, 1, 2, 3, 4])
        tm.assert_numpy_array_equal(result, expected)

        values = list("baaacb")
        result = safe_sort(values)
        expected = np.array(list("aaabbc"), dtype="object")
        tm.assert_numpy_array_equal(result, expected)

        values = []
        result = safe_sort(values)
        expected = np.array([])
        tm.assert_numpy_array_equal(result, expected)

    @pytest.mark.parametrize("verify", [True, False])
    def test_codes(self, verify):
        values = [3, 1, 2, 0, 4]
        expected = np.array([0, 1, 2, 3, 4])

        codes = [0, 1, 1, 2, 3, 0, -1, 4]
        result, result_codes = safe_sort(values, codes, verify=verify)
        expected_codes = np.array([3, 1, 1, 2, 0, 3, -1, 4], dtype=np.intp)
        tm.assert_numpy_array_equal(result, expected)
        tm.assert_numpy_array_equal(result_codes, expected_codes)

        # na_sentinel
        codes = [0, 1, 1, 2, 3, 0, 99, 4]
        result, result_codes = safe_sort(values, codes, na_sentinel=99, verify=verify)
        expected_codes = np.array([3, 1, 1, 2, 0, 3, 99, 4], dtype=np.intp)
        tm.assert_numpy_array_equal(result, expected)
        tm.assert_numpy_array_equal(result_codes, expected_codes)

        codes = []
        result, result_codes = safe_sort(values, codes, verify=verify)
        expected_codes = np.array([], dtype=np.intp)
        tm.assert_numpy_array_equal(result, expected)
        tm.assert_numpy_array_equal(result_codes, expected_codes)

    @pytest.mark.parametrize("na_sentinel", [-1, 99])
    def test_codes_out_of_bound(self, na_sentinel):
        values = [3, 1, 2, 0, 4]
        expected = np.array([0, 1, 2, 3, 4])

        # out of bound indices
        codes = [0, 101, 102, 2, 3, 0, 99, 4]
        result, result_codes = safe_sort(values, codes, na_sentinel=na_sentinel)
        expected_codes = np.array(
            [3, na_sentinel, na_sentinel, 2, 0, 3, na_sentinel, 4], dtype=np.intp
        )
        tm.assert_numpy_array_equal(result, expected)
        tm.assert_numpy_array_equal(result_codes, expected_codes)

    def test_mixed_integer(self):
        values = np.array(["b", 1, 0, "a", 0, "b"], dtype=object)
        result = safe_sort(values)
        expected = np.array([0, 0, 1, "a", "b", "b"], dtype=object)
        tm.assert_numpy_array_equal(result, expected)

        values = np.array(["b", 1, 0, "a"], dtype=object)
        codes = [0, 1, 2, 3, 0, -1, 1]
        result, result_codes = safe_sort(values, codes)
        expected = np.array([0, 1, "a", "b"], dtype=object)
        expected_codes = np.array([3, 1, 0, 2, 3, -1, 1], dtype=np.intp)
        tm.assert_numpy_array_equal(result, expected)
        tm.assert_numpy_array_equal(result_codes, expected_codes)

    def test_mixed_integer_from_list(self):
        values = ["b", 1, 0, "a", 0, "b"]
        result = safe_sort(values)
        expected = np.array([0, 0, 1, "a", "b", "b"], dtype=object)
        tm.assert_numpy_array_equal(result, expected)

    def test_unsortable(self):
        # GH 13714
        arr = np.array([1, 2, datetime.now(), 0, 3], dtype=object)
        msg = (
            "unorderable types: .* [<>] .*"
            "|"  # the above case happens for numpy < 1.14
            "'[<>]' not supported between instances of .*"
        )
        with pytest.raises(TypeError, match=msg):
            safe_sort(arr)

    def test_exceptions(self):
        with pytest.raises(TypeError, match="Only list-like objects are allowed"):
            safe_sort(values=1)

        with pytest.raises(TypeError, match="Only list-like objects or None"):
            safe_sort(values=[0, 1, 2], codes=1)

        with pytest.raises(ValueError, match="values should be unique"):
            safe_sort(values=[0, 1, 2, 1], codes=[0, 1])

    def test_extension_array(self):
        # a = array([1, 3, np.nan, 2], dtype='Int64')
        a = array([1, 3, 2], dtype="Int64")
        result = safe_sort(a)
        # expected = array([1, 2, 3, np.nan], dtype='Int64')
        expected = array([1, 2, 3], dtype="Int64")
        tm.assert_extension_array_equal(result, expected)

    @pytest.mark.parametrize("verify", [True, False])
    @pytest.mark.parametrize("na_sentinel", [-1, 99])
    def test_extension_array_codes(self, verify, na_sentinel):
        a = array([1, 3, 2], dtype="Int64")
        result, codes = safe_sort(
            a, [0, 1, na_sentinel, 2], na_sentinel=na_sentinel, verify=verify
        )
        expected_values = array([1, 2, 3], dtype="Int64")
        expected_codes = np.array([0, 2, na_sentinel, 1], dtype=np.intp)
        tm.assert_extension_array_equal(result, expected_values)
        tm.assert_numpy_array_equal(codes, expected_codes)


def test_mixed_str_nan():
    values = np.array(["b", np.nan, "a", "b"], dtype=object)
    result = safe_sort(values)
    expected = np.array([np.nan, "a", "b", "b"], dtype=object)
    tm.assert_numpy_array_equal(result, expected)