Function test_struct_from_arrays

python/pyarrow/tests/test_array.py:835–911

()

def test_struct_from_arrays():
    a = pa.array([4, 5, 6], type=pa.int64())
    b = pa.array(["bar", None, ""])
    c = pa.array([[1, 2], None, [3, None]])
    expected_list = [
        {'a': 4, 'b': 'bar', 'c': [1, 2]},
        {'a': 5, 'b': None, 'c': None},
        {'a': 6, 'b': '', 'c': [3, None]},
    ]

    # From field names
    arr = pa.StructArray.from_arrays([a, b, c], ["a", "b", "c"])
    assert arr.type == pa.struct(
        [("a", a.type), ("b", b.type), ("c", c.type)])
    assert arr.to_pylist() == expected_list

    with pytest.raises(ValueError):
        pa.StructArray.from_arrays([a, b, c], ["a", "b"])

    arr = pa.StructArray.from_arrays([], [])
    assert arr.type == pa.struct([])
    assert arr.to_pylist() == []

    # From fields
    fa = pa.field("a", a.type, nullable=False)
    fb = pa.field("b", b.type)
    fc = pa.field("c", c.type)
    arr = pa.StructArray.from_arrays([a, b, c], fields=[fa, fb, fc])
    assert arr.type == pa.struct([fa, fb, fc])
    assert not arr.type[0].nullable
    assert arr.to_pylist() == expected_list

    # From structtype
    structtype = pa.struct([fa, fb, fc])
    arr = pa.StructArray.from_arrays([a, b, c], type=structtype)
    assert arr.type == pa.struct([fa, fb, fc])
    assert not arr.type[0].nullable
    assert arr.to_pylist() == expected_list

    with pytest.raises(ValueError):
        pa.StructArray.from_arrays([a, b, c], fields=[fa, fb])

    arr = pa.StructArray.from_arrays([], fields=[])
    assert arr.type == pa.struct([])
    assert arr.to_pylist() == []

    # Inconsistent fields
    fa2 = pa.field("a", pa.int32())
    with pytest.raises(ValueError, match="int64 vs int32"):
        pa.StructArray.from_arrays([a, b, c], fields=[fa2, fb, fc])

    arrays = [a, b, c]
    fields = [fa, fb, fc]
    # With mask
    mask = pa.array([True, False, False])
    arr = pa.StructArray.from_arrays(arrays, fields=fields, mask=mask)
    assert arr.to_pylist() == [None] + expected_list[1:]