BUG: Fix Series.str has no method "isascii()"

pandas/core/arrays/string_arrow.py

@@ -459,6 +459,9 @@ def _str_isalpha(self):
         result = pc.utf8_is_alpha(self._pa_array)
         return self._result_converter(result)
 
+    def _str_isascii(self):
+        return super()._str_isascii()
+
     def _str_isdecimal(self):
         result = pc.utf8_is_decimal(self._pa_array)
         return self._result_converter(result)

pandas/core/strings/accessor.py

@@ -3320,7 +3320,8 @@ def casefold(self):
 
     This is equivalent to running the Python string method
     :meth:`str.%(method)s` for each element of the Series/Index. If a string
-    has zero characters, ``False`` is returned for that check.
+    has zero characters, ``False`` is returned for that check
+    except for the `isascii` method.
 
     Returns
     -------
@@ -3333,6 +3334,7 @@ def casefold(self):
     Series.str.isalpha : Check whether all characters are alphabetic.
     Series.str.isnumeric : Check whether all characters are numeric.
     Series.str.isalnum : Check whether all characters are alphanumeric.
+    Series.str.isascii : Check whether all characters are ASCII characters.
     Series.str.isdigit : Check whether all characters are digits.
     Series.str.isdecimal : Check whether all characters are decimal.
     Series.str.isspace : Check whether all characters are whitespace.
@@ -3367,6 +3369,13 @@ def casefold(self):
     3    False
     dtype: bool
 
+    >>> s1.str.isascii()
+    0     True
+    1     True
+    2     True
+    3     True
+    dtype: bool
+
     Note that checks against characters mixed with any additional punctuation
     or whitespace will evaluate to false for an alphanumeric check.
 
@@ -3457,6 +3466,7 @@ def casefold(self):
     """
     _doc_args["isalnum"] = {"type": "alphanumeric", "method": "isalnum"}
     _doc_args["isalpha"] = {"type": "alphabetic", "method": "isalpha"}
+    _doc_args["isascii"] = {"type": "ASCII characters", "method": "isascii"}
     _doc_args["isdigit"] = {"type": "digits", "method": "isdigit"}
     _doc_args["isspace"] = {"type": "whitespace", "method": "isspace"}
     _doc_args["islower"] = {"type": "lowercase", "method": "islower"}
@@ -3472,6 +3482,9 @@ def casefold(self):
     isalpha = _map_and_wrap(
         "isalpha", docstring=_shared_docs["ismethods"] % _doc_args["isalpha"]
     )
+    isascii = _map_and_wrap(
+        "isascii", docstring=_shared_docs["ismethods"] % _doc_args["isascii"]
+    )
     isdigit = _map_and_wrap(
         "isdigit", docstring=_shared_docs["ismethods"] % _doc_args["isdigit"]
     )

pandas/core/strings/base.py

@@ -174,6 +174,10 @@ def _str_isalnum(self):
     def _str_isalpha(self):
         pass
 
+    @abc.abstractmethod
+    def _str_isascii(self):
+        pass
+
     @abc.abstractmethod
     def _str_isdecimal(self):
         pass

pandas/core/strings/object_array.py

@@ -409,6 +409,9 @@ def _str_isalnum(self):
     def _str_isalpha(self):
         return self._str_map(str.isalpha, dtype="bool")
 
+    def _str_isascii(self):
+        return self._str_map(str.isascii, dtype="bool")
+
     def _str_isdecimal(self):
         return self._str_map(str.isdecimal, dtype="bool")
 

pandas/tests/strings/conftest.py

@@ -68,6 +68,7 @@
             "get_dummies",
             "isalnum",
             "isalpha",
+            "isascii",
             "isdecimal",
             "isdigit",
             "islower",
@@ -97,7 +98,6 @@
 )
 ids, _, _ = zip(*_any_string_method)  # use method name as fixture-id
 missing_methods = {f for f in dir(StringMethods) if not f.startswith("_")} - set(ids)
-
 # test that the above list captures all methods of StringMethods
 assert not missing_methods
 

pandas/tests/strings/test_strings.py

@@ -217,6 +217,19 @@ def test_ismethods(method, expected, any_string_dtype):
     assert list(result) == expected
 
 
+def test_isascii(any_string_dtype):
+    ser = Series(
+        ["a", "bb", "123", "あ", "\n", "", " ", "¼"],
+        dtype=any_string_dtype,
+    )
+    expected_dtype = "bool" if any_string_dtype in object_pyarrow_numpy else "boolean"
+    result = ser.str.isascii()
+    expected = Series(
+        [True, True, True, False, True, True, True, False], dtype=expected_dtype
+    )
+    tm.assert_series_equal(result, expected)
+
+
 @pytest.mark.parametrize(
     "method, expected",
     [