DEPR: actually deprecate cascaded_union in favor of unary_union (#2074)

geopandas/base.py

@@ -6,7 +6,6 @@ from pandas import DataFrame, Series
 
 from shapely.geometry import box
 from shapely.geometry.base import BaseGeometry
-from shapely.ops import cascaded_union
 
 from .array import GeometryArray, GeometryDtype
 
@@ -699,8 +698,13 @@ GeometryCollection
 
     @property
     def cascaded_union(self):
-        """Deprecated: Return the unary_union of all geometries"""
-        return cascaded_union(np.asarray(self.geometry.values))
+        """Deprecated: use `unary_union` instead"""
+        warn(
+            "The 'cascaded_union' attribute is deprecated, use 'unary_union' instead",
+            FutureWarning,
+            stacklevel=2,
+        )
+        return self.geometry.values.unary_union()
 
     @property
     def unary_union(self):

geopandas/tests/test_geom_methods.py

@@ -350,6 +350,16 @@ class TestGeomMethods:
 
         self._test_unary_topological("unary_union", expected, g)
 
+    def test_cascaded_union_deprecated(self):
+        p1 = self.t1
+        p2 = Polygon([(2, 0), (3, 0), (3, 1)])
+        g = GeoSeries([p1, p2])
+        with pytest.warns(
+            FutureWarning, match="The 'cascaded_union' attribute is deprecated"
+        ):
+            result = g.cascaded_union
+        assert result == g.unary_union
+
     def test_contains(self):
         expected = [True, False, True, False, False, False, False]
         assert_array_dtype_equal(expected, self.g0.contains(self.t1))

geopandas/tests/test_pandas_methods.py

@@ -476,7 +476,7 @@ def test_groupby(df):
     assert_frame_equal(res, exp)
 
     # applying on the geometry column
-    res = df.groupby("value2")["geometry"].apply(lambda x: x.cascaded_union)
+    res = df.groupby("value2")["geometry"].apply(lambda x: x.unary_union)
     if compat.PANDAS_GE_11:
         exp = GeoSeries(
             [shapely.geometry.MultiPoint([(0, 0), (2, 2)]), Point(1, 1)],