Edit

[EDIT] FILE: test_strings.py

import pytest

import operator
import numpy as np

from numpy.testing import assert_array_equal

COMPARISONS = [
    (operator.eq, np.equal, "=="),
    (operator.ne, np.not_equal, "!="),
    (operator.lt, np.less, "<"),
    (operator.le, np.less_equal, "<="),
    (operator.gt, np.greater, ">"),
    (operator.ge, np.greater_equal, ">="),
]

@pytest.mark.parametrize(["op", "ufunc", "sym"], COMPARISONS)
def test_mixed_string_comparison_ufuncs_fail(op, ufunc, sym):
    arr_string = np.array(["a", "b"], dtype="S")
    arr_unicode = np.array(["a", "c"], dtype="U")

with pytest.raises(TypeError, match="did not contain a loop"):
        ufunc(arr_string, arr_unicode)

with pytest.raises(TypeError, match="did not contain a loop"):
        ufunc(arr_unicode, arr_string)

@pytest.mark.parametrize(["op", "ufunc", "sym"], COMPARISONS)
def test_mixed_string_comparisons_ufuncs_with_cast(op, ufunc, sym):
    arr_string = np.array(["a", "b"], dtype="S")
    arr_unicode = np.array(["a", "c"], dtype="U")

# While there is no loop, manual casting is acceptable:
    res1 = ufunc(arr_string, arr_unicode, signature="UU->?", casting="unsafe")
    res2 = ufunc(arr_string, arr_unicode, signature="SS->?", casting="unsafe")

expected = op(arr_string.astype('U'), arr_unicode)
    assert_array_equal(res1, expected)
    assert_array_equal(res2, expected)

@pytest.mark.parametrize(["op", "ufunc", "sym"], COMPARISONS)
@pytest.mark.parametrize("dtypes", [
        ("S2", "S2"), ("S2", "S10"),
        ("<U1", "<U1"), ("<U1", ">U1"), (">U1", ">U1"),
        ("<U1", "<U10"), ("<U1", ">U10")])
@pytest.mark.parametrize("aligned", [True, False])
def test_string_comparisons(op, ufunc, sym, dtypes, aligned):
    # ensure native byte-order for the first view to stay within unicode range
    native_dt = np.dtype(dtypes[0]).newbyteorder("=")
    arr = np.arange(2**15).view(native_dt).astype(dtypes[0])
    if not aligned:
        # Make `arr` unaligned:
        new = np.zeros(arr.nbytes + 1, dtype=np.uint8)[1:].view(dtypes[0])
        new[...] = arr
        arr = new

arr2 = arr.astype(dtypes[1], copy=True)
    np.random.shuffle(arr2)
    arr[0] = arr2[0]  # make sure one matches

expected = [op(d1, d2) for d1, d2 in zip(arr.tolist(), arr2.tolist())]
    assert_array_equal(op(arr, arr2), expected)
    assert_array_equal(ufunc(arr, arr2), expected)
    assert_array_equal(np.compare_chararrays(arr, arr2, sym, False), expected)

expected = [op(d2, d1) for d1, d2 in zip(arr.tolist(), arr2.tolist())]
    assert_array_equal(op(arr2, arr), expected)
    assert_array_equal(ufunc(arr2, arr), expected)
    assert_array_equal(np.compare_chararrays(arr2, arr, sym, False), expected)

@pytest.mark.parametrize(["op", "ufunc", "sym"], COMPARISONS)
@pytest.mark.parametrize("dtypes", [
        ("S2", "S2"), ("S2", "S10"), ("<U1", "<U1"), ("<U1", ">U10")])
def test_string_comparisons_empty(op, ufunc, sym, dtypes):
    arr = np.empty((1, 0, 1, 5), dtype=dtypes[0])
    arr2 = np.empty((100, 1, 0, 1), dtype=dtypes[1])

expected = np.empty(np.broadcast_shapes(arr.shape, arr2.shape), dtype=bool)
    assert_array_equal(op(arr, arr2), expected)
    assert_array_equal(ufunc(arr, arr2), expected)
    assert_array_equal(np.compare_chararrays(arr, arr2, sym, False), expected)

@pytest.mark.parametrize("str_dt", ["S", "U"])
@pytest.mark.parametrize("float_dt", np.typecodes["AllFloat"])
def test_float_to_string_cast(str_dt, float_dt):
    float_dt = np.dtype(float_dt)
    fi = np.finfo(float_dt)
    arr = np.array([np.nan, np.inf, -np.inf, fi.max, fi.min], dtype=float_dt)
    expected = ["nan", "inf", "-inf", repr(fi.max), repr(fi.min)]
    if float_dt.kind == 'c':
        expected = [f"({r}+0j)" for r in expected]

res = arr.astype(str_dt)
    assert_array_equal(res, np.array(expected, dtype=str_dt))

CANCEL