Change comment

ml-agents/mlagents/trainers/ppo/trainer.py

         n_sequences = max(
             int(self.hyperparameters.batch_size / self.policy.sequence_length), 1
         )
-
-        advantages = self.update_buffer["advantages"].get_batch()
+        # Normalize advantages
+        advantages = np.array(self.update_buffer["advantages"].get_batch())
-            (advantages - advantages.mean()) / (advantages.std() + 1e-10)
+            list((advantages - advantages.mean()) / (advantages.std() + 1e-10))
         )
         num_epoch = self.hyperparameters.num_epoch
         batch_update_stats = defaultdict(list)

ml-agents/mlagents/trainers/tests/test_buffer.py

     b = AgentBuffer()
     for step in range(9):
         b["vector_observation"].append(
-            [
-                100 * fake_agent_id + 10 * step + 1,
-                100 * fake_agent_id + 10 * step + 2,
-                100 * fake_agent_id + 10 * step + 3,
-            ]
+            np.array(
+                [
+                    100 * fake_agent_id + 10 * step + 1,
+                    100 * fake_agent_id + 10 * step + 2,
+                    100 * fake_agent_id + 10 * step + 3,
+                ],
+                dtype=np.float32,
+            )
-            [100 * fake_agent_id + 10 * step + 4, 100 * fake_agent_id + 10 * step + 5]
+            np.array(
+                [
+                    100 * fake_agent_id + 10 * step + 4,
+                    100 * fake_agent_id + 10 * step + 5,
+                ],
+                dtype=np.float32,
+            )
         )
     return b
 
     a = agent_1_buffer["vector_observation"].get_batch(
         batch_size=2, training_length=1, sequential=True
     )
-    assert_array(np.array(a), np.array([[171, 172, 173], [181, 182, 183]]))
+    assert len(a) == 2
+    assert_array(
+        np.array(a), np.array([[171, 172, 173], [181, 182, 183]], dtype=np.float32)
+    )
     a = agent_2_buffer["vector_observation"].get_batch(
         batch_size=2, training_length=3, sequential=True
     )
                 [261, 262, 263],
                 [271, 272, 273],
                 [281, 282, 283],
-            ]
+            ],
+            dtype=np.float32,
         ),
     )
     a = agent_2_buffer["vector_observation"].get_batch(

ml-agents/mlagents/trainers/buffer.py

 import numpy as np
 import h5py
-from typing import List, BinaryIO
+from typing import List, BinaryIO, Any
 import itertools
 
 from mlagents_envs.exception import UnityException
 
     class AgentBufferField(list):
         """
-        AgentBufferField is a list of numpy arrays. When an agent collects a field, you can add it to his
-        AgentBufferField with the append method.
+        AgentBufferField is a list of data, usually numpy arrays. When an agent collects a field,
+        you can add it to its AgentBufferField with the append method.
         """
 
         def __init__(self):
         def __str__(self):
             return str(np.array(self).shape)
 
-        def append(self, element: np.ndarray, padding_value: float = 0.0) -> None:
+        def append(self, element: Any, padding_value: Any = 0.0) -> None:
-            Adds an element to this list. Also lets you change the padding
+            Adds an element to this AgentBuffer. Also lets you change the padding
             type, so that it can be set on append (e.g. action_masks should
             be padded with 1.)
             :param element: The element to append to the list.
             self.padding_value = padding_value
 
-        def extend(self, data: np.ndarray) -> None:
-            """
-            Adds a list of np.arrays to the end of the list of np.arrays.
-            :param data: The np.array list to append.
+        def set(self, data: List[Any]) -> None:
-            self += list(np.array(data, dtype=np.float32))
-
-        def set(self, data):
-            """
-            Sets the list of np.array to the input data
-            :param data: The np.array list to be set.
+            Sets the AgentBuffer to the provided list
+            :param data: The list to be set.
-            dtype = None
-            if data is not None and len(data) and isinstance(data[0], float):
-                dtype = np.float32
-            self[:] = list(np.array(data, dtype=dtype))
+            self[:] = data
 
         def get_batch(
             self,
-        ) -> np.ndarray:
+        ) -> List[Any]:
-            from the list of np.array
+            from the AgentBuffer.
             :param batch_size: The number of elements to retrieve. If None:
             All elements will be retrieved.
             :param training_length: The length of the sequence to be retrieved. If
                     )
                 if batch_size * training_length > len(self):
                     padding = np.array(self[-1], dtype=np.float32) * self.padding_value
-                    return np.array(
-                        [padding] * (training_length - leftover) + self[:],
-                        dtype=np.float32,
-                    )
+                    return [padding] * (training_length - leftover) + self[:]
-                    return np.array(
-                        self[len(self) - batch_size * training_length :],
-                        dtype=np.float32,
-                    )
+                    return self[len(self) - batch_size * training_length :]
             else:
                 # The sequences will have overlapping elements
                 if batch_size is None:
                 tmp_list: List[np.ndarray] = []
                 for end in range(len(self) - batch_size + 1, len(self) + 1):
                     tmp_list += self[end - training_length : end]
-                return np.array(tmp_list, dtype=np.float32)
+                return tmp_list
 
         def reset_field(self) -> None:
             """