dataframe: add copy interface

Signed-off-by: mgqa34 <mgq3374541@163.com>
Signed-off-by: sagewe <wbwmat@gmail.com>

python/fate/arch/dataframe/_dataframe.py

@@ -13,6 +13,7 @@
 #  See the License for the specific language governing permissions and
 #  limitations under the License.
 #
+import copy
 import operator
 from typing import List, Union
 
@@ -537,6 +538,14 @@ def _merge_list(lhs, rhs):
     def iloc(self, indexes):
         ...
 
+    def copy(self) -> "DataFrame":
+        return DataFrame(
+            self._ctx,
+            self._block_table.mapValues(lambda v: v),
+            copy.deepcopy(self.partition_order_mappings),
+            self._data_manager.duplicate()
+        )
+
     @classmethod
     def hstack(cls, stacks: List["DataFrame"]) -> "DataFrame":
         from .ops._dimension_scaling import hstack