ENH: Implement FloatingArray reductions (pandas-dev#36778)

Author: dsaxton

pandas/core/arrays/floating.py

@@ -25,8 +25,7 @@
 from pandas.core.dtypes.dtypes import register_extension_dtype
 from pandas.core.dtypes.missing import isna
 
-from pandas.core import nanops, ops
-from pandas.core.array_algos import masked_reductions
+from pandas.core import ops
 from pandas.core.ops import invalid_comparison
 from pandas.core.ops.common import unpack_zerodim_and_defer
 from pandas.core.tools.numeric import to_numeric
@@ -452,33 +451,21 @@ def cmp_method(self, other):
         name = f"__{op.__name__}__"
         return set_function_name(cmp_method, name, cls)
 
-    def _reduce(self, name: str, skipna: bool = True, **kwargs):
-        data = self._data
-        mask = self._mask
-
-        if name in {"sum", "prod", "min", "max"}:
-            op = getattr(masked_reductions, name)
-            return op(data, mask, skipna=skipna, **kwargs)
-
-        # coerce to a nan-aware float if needed
-        # (we explicitly use NaN within reductions)
-        if self._hasna:
-            data = self.to_numpy("float64", na_value=np.nan)
-
-        op = getattr(nanops, "nan" + name)
-        result = op(data, axis=0, skipna=skipna, mask=mask, **kwargs)
+    def sum(self, skipna=True, min_count=0, **kwargs):
+        nv.validate_sum((), kwargs)
+        return super()._reduce("sum", skipna=skipna, min_count=min_count)
 
-        if np.isnan(result):
-            return libmissing.NA
+    def prod(self, skipna=True, min_count=0, **kwargs):
+        nv.validate_prod((), kwargs)
+        return super()._reduce("prod", skipna=skipna, min_count=min_count)
 
-        return result
+    def min(self, skipna=True, **kwargs):
+        nv.validate_min((), kwargs)
+        return super()._reduce("min", skipna=skipna)
 
-    def sum(self, skipna=True, min_count=0, **kwargs):
-        nv.validate_sum((), kwargs)
-        result = masked_reductions.sum(
-            values=self._data, mask=self._mask, skipna=skipna, min_count=min_count
-        )
-        return result
+    def max(self, skipna=True, **kwargs):
+        nv.validate_max((), kwargs)
+        return super()._reduce("max", skipna=skipna)
 
     def _maybe_mask_result(self, result, mask, other, op_name: str):
         """

pandas/tests/arrays/floating/test_function.py

@@ -112,8 +112,8 @@ def test_value_counts_empty():
 
 @pytest.mark.parametrize("skipna", [True, False])
 @pytest.mark.parametrize("min_count", [0, 4])
-def test_floating_array_sum(skipna, min_count):
-    arr = pd.array([1, 2, 3, None], dtype="Float64")
+def test_floating_array_sum(skipna, min_count, dtype):
+    arr = pd.array([1, 2, 3, None], dtype=dtype)
     result = arr.sum(skipna=skipna, min_count=min_count)
     if skipna and min_count == 0:
         assert result == 6.0
@@ -152,3 +152,26 @@ def test_preserve_dtypes(op):
         index=pd.Index(["a", "b"], name="A"),
     )
     tm.assert_frame_equal(result, expected)
+
+
+@pytest.mark.parametrize("skipna", [True, False])
+@pytest.mark.parametrize("method", ["min", "max"])
+def test_floating_array_min_max(skipna, method, dtype):
+    arr = pd.array([0.0, 1.0, None], dtype=dtype)
+    func = getattr(arr, method)
+    result = func(skipna=skipna)
+    if skipna:
+        assert result == (0 if method == "min" else 1)
+    else:
+        assert result is pd.NA
+
+
+@pytest.mark.parametrize("skipna", [True, False])
+@pytest.mark.parametrize("min_count", [0, 9])
+def test_floating_array_prod(skipna, min_count, dtype):
+    arr = pd.array([1.0, 2.0, None], dtype=dtype)
+    result = arr.prod(skipna=skipna, min_count=min_count)
+    if skipna and min_count == 0:
+        assert result == 2
+    else:
+        assert result is pd.NA