pct change bug issue 21200

pandas/core/groupby/generic.py

@@ -35,25 +35,9 @@
 from pandas.core.generic import NDFrame, _shared_docs
 from pandas.core.groupby import base
 from pandas.core.groupby.groupby import (
-    GroupBy, _apply_docs, _transform_template, _group_selection_context)
-from pandas.core.generic import NDFrame
-from pandas.core.groupby import base
-from pandas.core.dtypes.common import (
-    is_scalar,
-    is_bool,
-    is_datetimelike,
-    is_numeric_dtype,
-    is_integer_dtype,
-    is_interval_dtype,
-    ensure_platform_int,
-    ensure_int64)
-from pandas.core.dtypes.missing import isna, notna
-import pandas.core.algorithms as algorithms
-from pandas.core.frame import DataFrame
-from pandas.core.dtypes.cast import maybe_downcast_to_dtype
-from pandas.core.base import SpecificationError, DataError
-from pandas.core.index import Index, MultiIndex, CategoricalIndex
-from pandas.core.arrays.categorical import Categorical
+    GroupBy, _apply_docs, _transform_template)
+from pandas.core.index import CategoricalIndex, Index, MultiIndex
+import pandas.core.indexes.base as ibase
 from pandas.core.internals import BlockManager, make_block
 from pandas.core.panel import Panel
 from pandas.core.series import Series

pandas/core/groupby/groupby.py

@@ -8,8 +8,6 @@ class providing the base-class of operations.
 """
 
 import collections
-import warnings
-import copy
 from contextlib import contextmanager
 import datetime
 from functools import partial, wraps