docstring

stable_baselines3/common/buffers.py

@@ -396,6 +396,23 @@ class RolloutBuffer(BaseBuffer):
 
 
 class NstepReplayBuffer(ReplayBuffer):
+    """
+    Replay Buffer that computes N-step returns.
+
+    :param buffer_size: (int) Max number of element in the buffer
+    :param observation_space: (spaces.Space) Observation space
+    :param action_space: (spaces.Space) Action space
+    :param device: (Union[th.device, str]) PyTorch device
+        to which the values will be converted
+    :param n_envs: (int) Number of parallel environments
+    :param optimize_memory_usage: (bool) Enable a memory efficient variant
+        of the replay buffer which reduces by almost a factor two the memory used,
+        at a cost of more complexity.
+        See https://github.com/DLR-RM/stable-baselines3/issues/37#issuecomment-637501195
+        and https://github.com/DLR-RM/stable-baselines3/pull/28#issuecomment-637559274
+    :param n_step: (int) The number of transitions to consider when computing n-step returns
+    :param gamma:  (float) The discount factor for future rewards.
+    """
     def __init__(
         self,
         buffer_size: int,