Add list type of feeding

Author: reyoung

python/paddle/v2/data_feeder.py

@@ -13,7 +13,7 @@
 # limitations under the License.
 
 from py_paddle import DataProviderConverter
-
+import collections
 import paddle.trainer.PyDataProvider2 as pydp2
 
 __all__ = ['DataFeeder']
@@ -75,6 +75,13 @@ def __init__(self, data_types, feeding=None):
         input_types = []
         if feeding is None:
             feeding = default_feeding_map(data_types)
+        elif isinstance(feeding, collections.Sequence):
+            feed_list = feeding
+            feeding = dict()
+            for i, name in enumerate(feed_list):
+                feeding[name] = i
+        elif not isinstance(feeding, dict):
+            raise TypeError("Feeding should be dict or sequence or None.")
 
         self.feeding = feeding
         for each in data_types: