ENH: Implement more string accessors through PyArrow (pandas-dev#54960)

Author: phofl

pandas/core/arrays/string_arrow.py

@@ -50,6 +50,8 @@
 
 
 if TYPE_CHECKING:
+    from collections.abc import Sequence
+
     from pandas._typing import (
         Dtype,
         Scalar,
@@ -337,19 +339,13 @@ def _str_startswith(self, pat: str, na=None):
         result = pc.starts_with(self._pa_array, pattern=pat)
         if not isna(na):
             result = result.fill_null(na)
-        result = self._result_converter(result)
-        if not isna(na):
-            result[isna(result)] = bool(na)
-        return result
+        return self._result_converter(result)
 
     def _str_endswith(self, pat: str, na=None):
         result = pc.ends_with(self._pa_array, pattern=pat)
         if not isna(na):
             result = result.fill_null(na)
-        result = self._result_converter(result)
-        if not isna(na):
-            result[isna(result)] = bool(na)
-        return result
+        return self._result_converter(result)
 
     def _str_replace(
         self,
@@ -368,6 +364,12 @@ def _str_replace(
         result = func(self._pa_array, pattern=pat, replacement=repl, max_replacements=n)
         return type(self)(result)
 
+    def _str_repeat(self, repeats: int | Sequence[int]):
+        if not isinstance(repeats, int):
+            return super()._str_repeat(repeats)
+        else:
+            return type(self)(pc.binary_repeat(self._pa_array, repeats))
+
     def _str_match(
         self, pat: str, case: bool = True, flags: int = 0, na: Scalar | None = None
     ):
@@ -382,6 +384,19 @@ def _str_fullmatch(
             pat = f"{pat}$"
         return self._str_match(pat, case, flags, na)
 
+    def _str_slice(
+        self, start: int | None = None, stop: int | None = None, step: int | None = None
+    ):
+        if stop is None:
+            return super()._str_slice(start, stop, step)
+        if start is None:
+            start = 0
+        if step is None:
+            step = 1
+        return type(self)(
+            pc.utf8_slice_codeunits(self._pa_array, start=start, stop=stop, step=step)
+        )
+
     def _str_isalnum(self):
         result = pc.utf8_is_alnum(self._pa_array)
         return self._result_converter(result)