ENH: support pathlib.Path division in StringArray (pandas-dev#62229)

Author: jbrockmendel

pandas/core/arrays/arrow/array.py

@@ -2,6 +2,7 @@
 
 import functools
 import operator
+from pathlib import Path
 import re
 import textwrap
 from typing import (
@@ -951,7 +952,23 @@ def _logical_method(self, other, op) -> Self:
         else:
             return self._evaluate_op_method(other, op, ARROW_LOGICAL_FUNCS)
 
-    def _arith_method(self, other, op) -> Self:
+    def _arith_method(self, other, op) -> Self | npt.NDArray[np.object_]:
+        if (
+            op in [operator.truediv, roperator.rtruediv]
+            and isinstance(other, Path)
+            and (
+                pa.types.is_string(self._pa_array.type)
+                or pa.types.is_large_string(self._pa_array.type)
+            )
+        ):
+            # GH#61940
+            return np.array(
+                [
+                    op(x, other) if isinstance(x, str) else self.dtype.na_value
+                    for x in self
+                ],
+                dtype=object,
+            )
         return self._evaluate_op_method(other, op, ARROW_ARITHMETIC_FUNCS)
 
     def equals(self, other) -> bool:

pandas/core/arrays/string_.py

@@ -2,6 +2,7 @@
 
 from functools import partial
 import operator
+from pathlib import Path
 from typing import (
     TYPE_CHECKING,
     Any,
@@ -1065,7 +1066,7 @@ def _cmp_method(self, other, op):
         mask = isna(self) | isna(other)
         valid = ~mask
 
-        if not lib.is_scalar(other):
+        if lib.is_list_like(other):
             if len(other) != len(self):
                 # prevent improper broadcasting when other is 2D
                 raise ValueError(
@@ -1081,6 +1082,9 @@ def _cmp_method(self, other, op):
             result = np.empty_like(self._ndarray, dtype="object")
             result[mask] = self.dtype.na_value
             result[valid] = op(self._ndarray[valid], other)
+            if isinstance(other, Path):
+                # GH#61940
+                return result
             return self._from_backing_data(result)
         else:
             # logical

pandas/tests/strings/test_strings.py

@@ -2,6 +2,7 @@
     datetime,
     timedelta,
 )
+from pathlib import Path
 
 import numpy as np
 import pytest
@@ -824,3 +825,24 @@ def test_reversed_logical_ops(any_string_dtype):
         result = left ^ right
     expected = left ^ right.astype(bool)
     tm.assert_series_equal(result, expected)
+
+
+def test_pathlib_path_division(any_string_dtype, request):
+    # GH#61940
+    if any_string_dtype == object:
+        mark = pytest.mark.xfail(
+            reason="with NA present we go through _masked_arith_op which "
+            "raises TypeError bc Path is not recognized by lib.is_scalar."
+        )
+        request.applymarker(mark)
+
+    item = Path("/Users/Irv/")
+    ser = Series(["A", "B", NA], dtype=any_string_dtype)
+
+    result = item / ser
+    expected = Series([item / "A", item / "B", ser.dtype.na_value], dtype=object)
+    tm.assert_series_equal(result, expected)
+
+    result = ser / item
+    expected = Series(["A" / item, "B" / item, ser.dtype.na_value], dtype=object)
+    tm.assert_series_equal(result, expected)