Merge pull request #5879 from madsbk/concat_sub_types

[REVIEW] concat(): support sub-types and object wrappers

CHANGELOG.md

@@ -183,6 +183,7 @@
 - PR #5853 Disable `fixed_point` for use in `copy_if`
 - PR #5854 Raise informative error in `DataFrame.iterrows` and `DataFrame.itertuples`
 - PR #5863 Explicitly require `ucx-py` on CI
+- PR #5879 Added support of sub-types and object wrappers in concat()
 - PR #5884 Use S3 bucket directly for benchmark plugni
 - PR #5881 Add in JVM extractListElement and stringSplitRecord
 - PR #5885 Add in java support for merge sort

python/cudf/cudf/core/reshape.py

@@ -190,7 +190,22 @@ def concat(objs, axis=0, ignore_index=False, sort=None):
     if len(objs) == 0:
         raise ValueError("All objects passed were None")
 
-    typs = set(type(o) for o in objs)
+    # Retrieve the base types of `objs`. In order to support sub-types
+    # and object wrappers, we use `isinstance()` instead of comparing
+    # types directly
+    typs = set()
+    for o in objs:
+        if isinstance(o, cudf.MultiIndex):
+            typs.add(cudf.MultiIndex)
+        if issubclass(type(o), Index):
+            typs.add(type(o))
+        elif isinstance(o, DataFrame):
+            typs.add(DataFrame)
+        elif isinstance(o, Series):
+            typs.add(Series)
+        else:
+            raise ValueError(f"cannot concatenate object of type {type(o)}")
+
     allowed_typs = {Series, DataFrame}
 
     param_axis = _axis_map.get(axis, None)