From 471b7776229d8d88a45b7c33b1984dd6da08a90c Mon Sep 17 00:00:00 2001
From: Brock <jbrockmendel@gmail.com>
Date: Sat, 21 Jan 2023 15:39:28 -0800
Subject: [PATCH] ENH: support min/max/sum for pyarrow duration dtypes

---
 pandas/core/arrays/arrow/array.py      | 12 +++++++++++-
 pandas/tests/extension/base/groupby.py |  1 +
 pandas/tests/extension/test_arrow.py   |  4 ----
 3 files changed, 12 insertions(+), 5 deletions(-)

diff --git a/pandas/core/arrays/arrow/array.py b/pandas/core/arrays/arrow/array.py
index e2a74ea6f5351..a6a83feb24435 100644
--- a/pandas/core/arrays/arrow/array.py
+++ b/pandas/core/arrays/arrow/array.py
@@ -1033,8 +1033,15 @@ def pyarrow_meth(data, skip_nulls, **kwargs):
             if pyarrow_meth is None:
                 # Let ExtensionArray._reduce raise the TypeError
                 return super()._reduce(name, skipna=skipna, **kwargs)
+
+        data_to_reduce = self._data
+
+        pa_dtype = self._data.type
+        if name in ["min", "max", "sum"] and pa.types.is_duration(pa_dtype):
+            data_to_reduce = self._data.cast(pa.int64())
+
         try:
-            result = pyarrow_meth(self._data, skip_nulls=skipna, **kwargs)
+            result = pyarrow_meth(data_to_reduce, skip_nulls=skipna, **kwargs)
         except (AttributeError, NotImplementedError, TypeError) as err:
             msg = (
                 f"'{type(self).__name__}' with dtype {self.dtype} "
@@ -1045,6 +1052,9 @@ def pyarrow_meth(data, skip_nulls, **kwargs):
             raise TypeError(msg) from err
         if pc.is_null(result).as_py():
             return self.dtype.na_value
+
+        if name in ["min", "max", "sum"] and pa.types.is_duration(pa_dtype):
+            result = result.cast(pa_dtype)
         return result.as_py()
 
     def __setitem__(self, key, value) -> None:
diff --git a/pandas/tests/extension/base/groupby.py b/pandas/tests/extension/base/groupby.py
index 3a9dbe9dfb384..200a494997116 100644
--- a/pandas/tests/extension/base/groupby.py
+++ b/pandas/tests/extension/base/groupby.py
@@ -137,6 +137,7 @@ def test_in_numeric_groupby(self, data_for_grouping):
             or is_string_dtype(dtype)
             or is_period_dtype(dtype)
             or is_object_dtype(dtype)
+            or dtype.kind == "m"  # in particular duration[*][pyarrow]
         ):
             expected = pd.Index(["B", "C"])
             result = df.groupby("A").sum().columns
diff --git a/pandas/tests/extension/test_arrow.py b/pandas/tests/extension/test_arrow.py
index a7c243cdfe74f..91a725234359a 100644
--- a/pandas/tests/extension/test_arrow.py
+++ b/pandas/tests/extension/test_arrow.py
@@ -539,10 +539,6 @@ def test_reduce_series(self, data, all_numeric_reductions, skipna, request):
             "sem",
         ] and pa.types.is_temporal(pa_dtype):
             request.node.add_marker(xfail_mark)
-        elif all_numeric_reductions in ["sum", "min", "max"] and pa.types.is_duration(
-            pa_dtype
-        ):
-            request.node.add_marker(xfail_mark)
         elif pa.types.is_boolean(pa_dtype) and all_numeric_reductions in {
             "sem",
             "std",