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Backport PR #41958 on branch 1.3.x (REGR: Series[dt64/td64].astype(string)) #42028

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8 changes: 8 additions & 0 deletions pandas/_libs/lib.pyx
Original file line number Diff line number Diff line change
Expand Up @@ -716,6 +716,14 @@ cpdef ndarray[object] ensure_string_array(
Py_ssize_t i = 0, n = len(arr)

if hasattr(arr, "to_numpy"):

if hasattr(arr, "dtype") and arr.dtype.kind in ["m", "M"]:
# dtype check to exclude DataFrame
# GH#41409 TODO: not a great place for this
out = arr.astype(str).astype(object)
out[arr.isna()] = na_value
return out

arr = arr.to_numpy()
elif not isinstance(arr, np.ndarray):
arr = np.array(arr, dtype="object")
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17 changes: 11 additions & 6 deletions pandas/tests/frame/methods/test_astype.py
Original file line number Diff line number Diff line change
Expand Up @@ -632,13 +632,9 @@ def test_astype_tz_object_conversion(self, tz):
result = result.astype({"tz": "datetime64[ns, Europe/London]"})
tm.assert_frame_equal(result, expected)

def test_astype_dt64_to_string(self, frame_or_series, tz_naive_fixture, request):
def test_astype_dt64_to_string(self, frame_or_series, tz_naive_fixture):
# GH#41409
tz = tz_naive_fixture
if tz is None:
mark = pytest.mark.xfail(
reason="GH#36153 uses ndarray formatting instead of DTA formatting"
)
request.node.add_marker(mark)

dti = date_range("2016-01-01", periods=3, tz=tz)
dta = dti._data
Expand All @@ -660,6 +656,15 @@ def test_astype_dt64_to_string(self, frame_or_series, tz_naive_fixture, request)
alt = obj.astype(str)
assert np.all(alt.iloc[1:] == result.iloc[1:])

def test_astype_td64_to_string(self, frame_or_series):
# GH#41409
tdi = pd.timedelta_range("1 Day", periods=3)
obj = frame_or_series(tdi)

expected = frame_or_series(["1 days", "2 days", "3 days"], dtype="string")
result = obj.astype("string")
tm.assert_equal(result, expected)

def test_astype_bytes(self):
# GH#39474
result = DataFrame(["foo", "bar", "baz"]).astype(bytes)
Expand Down