ENH: Use more arrow compute functions for string[pyarrow] dtype (#54957)

Author: phofl

pandas/core/arrays/string_arrow.py

@@ -417,7 +417,7 @@ def _str_isupper(self):
 
     def _str_len(self):
         result = pc.utf8_length(self._pa_array)
-        return Int64Dtype().__from_arrow__(result)
+        return self._convert_int_dtype(result)
 
     def _str_lower(self):
         return type(self)(pc.utf8_lower(self._pa_array))
@@ -446,6 +446,29 @@ def _str_rstrip(self, to_strip=None):
             result = pc.utf8_rtrim(self._pa_array, characters=to_strip)
         return type(self)(result)
 
+    def _str_count(self, pat: str, flags: int = 0):
+        if flags:
+            return super()._str_count(pat, flags)
+        result = pc.count_substring_regex(self._pa_array, pat)
+        return self._convert_int_dtype(result)
+
+    def _str_find(self, sub: str, start: int = 0, end: int | None = None):
+        if start != 0 and end is not None:
+            slices = pc.utf8_slice_codeunits(self._pa_array, start, stop=end)
+            result = pc.find_substring(slices, sub)
+            not_found = pc.equal(result, -1)
+            offset_result = pc.add(result, end - start)
+            result = pc.if_else(not_found, result, offset_result)
+        elif start == 0 and end is None:
+            slices = self._pa_array
+            result = pc.find_substring(slices, sub)
+        else:
+            return super()._str_find(sub, start, end)
+        return self._convert_int_dtype(result)
+
+    def _convert_int_dtype(self, result):
+        return Int64Dtype().__from_arrow__(result)
+
 
 class ArrowStringArrayNumpySemantics(ArrowStringArray):
     _storage = "pyarrow_numpy"
@@ -526,34 +549,11 @@ def _str_map(
             return lib.map_infer_mask(arr, f, mask.view("uint8"))
 
     def _convert_int_dtype(self, result):
+        result = result.to_numpy()
         if result.dtype == np.int32:
             result = result.astype(np.int64)
         return result
 
-    def _str_count(self, pat: str, flags: int = 0):
-        if flags:
-            return super()._str_count(pat, flags)
-        result = pc.count_substring_regex(self._pa_array, pat).to_numpy()
-        return self._convert_int_dtype(result)
-
-    def _str_len(self):
-        result = pc.utf8_length(self._pa_array).to_numpy()
-        return self._convert_int_dtype(result)
-
-    def _str_find(self, sub: str, start: int = 0, end: int | None = None):
-        if start != 0 and end is not None:
-            slices = pc.utf8_slice_codeunits(self._pa_array, start, stop=end)
-            result = pc.find_substring(slices, sub)
-            not_found = pc.equal(result, -1)
-            offset_result = pc.add(result, end - start)
-            result = pc.if_else(not_found, result, offset_result)
-        elif start == 0 and end is None:
-            slices = self._pa_array
-            result = pc.find_substring(slices, sub)
-        else:
-            return super()._str_find(sub, start, end)
-        return self._convert_int_dtype(result.to_numpy())
-
     def _cmp_method(self, other, op):
         result = super()._cmp_method(other, op)
         return result.to_numpy(np.bool_, na_value=False)