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import numpy as np
import pytest
from pandas.core.dtypes import dtypes
from pandas.core.dtypes.common import is_extension_array_dtype
import pandas as pd
import pandas._testing as tm
from pandas.core.arrays import ExtensionArray
class DummyDtype(dtypes.ExtensionDtype):
pass
class DummyArray(ExtensionArray):
def __init__(self, data) -> None:
self.data = data
def __array__(self, dtype):
return self.data
@property
def dtype(self):
return DummyDtype()
def astype(self, dtype, copy=True):
# we don't support anything but a single dtype
if isinstance(dtype, DummyDtype):
if copy:
return type(self)(self.data)
return self
return np.array(self, dtype=dtype, copy=copy)
class TestExtensionArrayDtype:
@pytest.mark.parametrize(
"values",
[
pd.Categorical([]),
pd.Categorical([]).dtype,
pd.Series(pd.Categorical([])),
DummyDtype(),
DummyArray(np.array([1, 2])),
],
)
def test_is_extension_array_dtype(self, values):
assert is_extension_array_dtype(values)
@pytest.mark.parametrize("values", [np.array([]), pd.Series(np.array([]))])
def test_is_not_extension_array_dtype(self, values):
assert not is_extension_array_dtype(values)
def test_astype():
arr = DummyArray(np.array([1, 2, 3]))
expected = np.array([1, 2, 3], dtype=object)
result = arr.astype(object)
tm.assert_numpy_array_equal(result, expected)
result = arr.astype("object")
tm.assert_numpy_array_equal(result, expected)
def test_astype_no_copy():
arr = DummyArray(np.array([1, 2, 3], dtype=np.int64))
result = arr.astype(arr.dtype, copy=False)
assert arr is result
result = arr.astype(arr.dtype)
assert arr is not result
@pytest.mark.parametrize("dtype", [dtypes.CategoricalDtype(), dtypes.IntervalDtype()])
def test_is_extension_array_dtype(dtype):
assert isinstance(dtype, dtypes.ExtensionDtype)
assert is_extension_array_dtype(dtype)
class CapturingStringArray(pd.arrays.StringArray):
"""Extend StringArray to capture arguments to __getitem__"""
def __getitem__(self, item):
self.last_item_arg = item
return super().__getitem__(item)
def test_ellipsis_index():
# GH#42430 1D slices over extension types turn into N-dimensional slices
# over ExtensionArrays
df = pd.DataFrame(
{"col1": CapturingStringArray(np.array(["hello", "world"], dtype=object))}
)
_ = df.iloc[:1]
# String comparison because there's no native way to compare slices.
# Before the fix for GH#42430, last_item_arg would get set to the 2D slice
# (Ellipsis, slice(None, 1, None))
out = df["col1"].array.last_item_arg
assert str(out) == "slice(None, 1, None)"