.. DO NOT EDIT. .. THIS FILE WAS AUTOMATICALLY GENERATED BY SPHINX-GALLERY. .. TO MAKE CHANGES, EDIT THE SOURCE PYTHON FILE: .. "tutorials/dqn_with_rnn.py" .. LINE NUMBERS ARE GIVEN BELOW. .. only:: html .. note:: :class: sphx-glr-download-link-note :ref:`Go to the end ` to download the full example code .. rst-class:: sphx-glr-example-title .. _sphx_glr_tutorials_dqn_with_rnn.py: Recurrent DQN: Training recurrent policies ========================================== **Author**: `Vincent Moens `_ .. _RNN_tuto: .. grid:: 2 .. grid-item-card:: :octicon:`mortar-board;1em;` What you will learn * How to incorporating an RNN in an actor in TorchRL * How to use that memory-based policy with a replay buffer and a loss module .. grid-item-card:: :octicon:`list-unordered;1em;` Prerequisites * PyTorch v2.0.0 * gym[mujoco] * tqdm .. GENERATED FROM PYTHON SOURCE LINES 26-59 Overview -------- Memory-based policies are crucial not only when the observations are partially observable but also when the time dimension must be taken into account to make informed decisions. Recurrent neural network have long been a popular tool for memory-based policies. The idea is to keep a recurrent state in memory between two consecutive steps, and use this as an input to the policy along with the current observation. This tutorial shows how to incorporate an RNN in a policy using TorchRL. Key learnings: - Incorporating an RNN in an actor in TorchRL; - Using that memory-based policy with a replay buffer and a loss module. The core idea of using RNNs in TorchRL is to use TensorDict as a data carrier for the hidden states from one step to another. We'll build a policy that reads the previous recurrent state from the current TensorDict, and writes the current recurrent states in the TensorDict of the next state: .. figure:: /_static/img/rollout_recurrent.png :alt: Data collection with a recurrent policy As this figure shows, our environment populates the TensorDict with zeroed recurrent states which are read by the policy together with the observation to produce an action, and recurrent states that will be used for the next step. When the :func:`~torchrl.envs.utils.step_mdp` function is called, the recurrent states from the next state are brought to the current TensorDict. Let's see how this is implemented in practice. .. GENERATED FROM PYTHON SOURCE LINES 61-72 If you are running this in Google Colab, make sure you install the following dependencies: .. code-block:: bash !pip3 install torchrl !pip3 install gym[mujoco] !pip3 install tqdm Setup ----- .. GENERATED FROM PYTHON SOURCE LINES 72-108 .. code-block:: Python import torch import tqdm from tensordict.nn import ( TensorDictModule as Mod, TensorDictSequential, TensorDictSequential as Seq, ) from torch import nn from torchrl.collectors import SyncDataCollector from torchrl.data import LazyMemmapStorage, TensorDictReplayBuffer from torchrl.envs import ( Compose, ExplorationType, GrayScale, InitTracker, ObservationNorm, Resize, RewardScaling, set_exploration_type, StepCounter, ToTensorImage, TransformedEnv, ) from torchrl.envs.libs.gym import GymEnv from torchrl.modules import ConvNet, EGreedyModule, LSTMModule, MLP, QValueModule from torchrl.objectives import DQNLoss, SoftUpdate is_fork = multiprocessing.get_start_method() == "fork" device = ( torch.device(0) if torch.cuda.is_available() and not is_fork else torch.device("cpu") ) .. GENERATED FROM PYTHON SOURCE LINES 129-166 Environment ----------- As usual, the first step is to build our environment: it helps us define the problem and build the policy network accordingly. For this tutorial, we'll be running a single pixel-based instance of the CartPole gym environment with some custom transforms: turning to grayscale, resizing to 84x84, scaling down the rewards and normalizing the observations. .. note:: The :class:`~torchrl.envs.transforms.StepCounter` transform is accessory. Since the CartPole task goal is to make trajectories as long as possible, counting the steps can help us track the performance of our policy. Two transforms are important for the purpose of this tutorial: - :class:`~torchrl.envs.transforms.InitTracker` will stamp the calls to :meth:`~torchrl.envs.EnvBase.reset` by adding a ``"is_init"`` boolean mask in the TensorDict that will track which steps require a reset of the RNN hidden states. - The :class:`~torchrl.envs.transforms.TensorDictPrimer` transform is a bit more technical. It is not required to use RNN policies. However, it instructs the environment (and subsequently the collector) that some extra keys are to be expected. Once added, a call to `env.reset()` will populate the entries indicated in the primer with zeroed tensors. Knowing that these tensors are expected by the policy, the collector will pass them on during collection. Eventually, we'll be storing our hidden states in the replay buffer, which will help us bootstrap the computation of the RNN operations in the loss module (which would otherwise be initiated with 0s). In summary: not including this transform will not impact hugely the training of our policy, but it will make the recurrent keys disappear from the collected data and the replay buffer, which will in turn lead to a slightly less optimal training. Fortunately, the :class:`~torchrl.modules.LSTMModule` we propose is equipped with a helper method to build just that transform for us, so we can wait until we build it! .. GENERATED FROM PYTHON SOURCE LINES 166-180 .. code-block:: Python env = TransformedEnv( GymEnv("CartPole-v1", from_pixels=True, device=device), Compose( ToTensorImage(), GrayScale(), Resize(84, 84), StepCounter(), InitTracker(), RewardScaling(loc=0.0, scale=0.1), ObservationNorm(standard_normal=True, in_keys=["pixels"]), ), ) .. GENERATED FROM PYTHON SOURCE LINES 181-183 As always, we need to initialize manually our normalization constants: .. GENERATED FROM PYTHON SOURCE LINES 183-186 .. code-block:: Python env.transform[-1].init_stats(1000, reduce_dim=[0, 1, 2], cat_dim=0, keep_dims=[0]) td = env.reset() .. GENERATED FROM PYTHON SOURCE LINES 187-202 Policy ------ Our policy will have 3 components: a :class:`~torchrl.modules.ConvNet` backbone, an :class:`~torchrl.modules.LSTMModule` memory layer and a shallow :class:`~torchrl.modules.MLP` block that will map the LSTM output onto the action values. Convolutional network ~~~~~~~~~~~~~~~~~~~~~ We build a convolutional network flanked with a :class:`torch.nn.AdaptiveAvgPool2d` that will squash the output in a vector of size 64. The :class:`~torchrl.modules.ConvNet` can assist us with this: .. GENERATED FROM PYTHON SOURCE LINES 202-214 .. code-block:: Python feature = Mod( ConvNet( num_cells=[32, 32, 64], squeeze_output=True, aggregator_class=nn.AdaptiveAvgPool2d, aggregator_kwargs={"output_size": (1, 1)}, device=device, ), in_keys=["pixels"], out_keys=["embed"], ) .. GENERATED FROM PYTHON SOURCE LINES 215-218 we execute the first module on a batch of data to gather the size of the output vector: .. GENERATED FROM PYTHON SOURCE LINES 218-220 .. code-block:: Python n_cells = feature(env.reset())["embed"].shape[-1] .. GENERATED FROM PYTHON SOURCE LINES 221-243 LSTM Module ~~~~~~~~~~~ TorchRL provides a specialized :class:`~torchrl.modules.LSTMModule` class to incorporate LSTMs in your code-base. It is a :class:`~tensordict.nn.TensorDictModuleBase` subclass: as such, it has a set of ``in_keys`` and ``out_keys`` that indicate what values should be expected to be read and written/updated during the execution of the module. The class comes with customizable predefined values for these attributes to facilitate its construction. .. note:: *Usage limitations*: The class supports almost all LSTM features such as dropout or multi-layered LSTMs. However, to respect TorchRL's conventions, this LSTM must have the ``batch_first`` attribute set to ``True`` which is **not** the default in PyTorch. However, our :class:`~torchrl.modules.LSTMModule` changes this default behavior, so we're good with a native call. Also, the LSTM cannot have a ``bidirectional`` attribute set to ``True`` as this wouldn't be usable in online settings. In this case, the default value is the correct one. .. GENERATED FROM PYTHON SOURCE LINES 243-252 .. code-block:: Python lstm = LSTMModule( input_size=n_cells, hidden_size=128, device=device, in_key="embed", out_key="embed", ) .. GENERATED FROM PYTHON SOURCE LINES 253-254 Let us look at the LSTM Module class, specifically its in and out_keys: .. GENERATED FROM PYTHON SOURCE LINES 254-257 .. code-block:: Python print("in_keys", lstm.in_keys) print("out_keys", lstm.out_keys) .. rst-class:: sphx-glr-script-out .. code-block:: none in_keys ['embed', 'recurrent_state_h', 'recurrent_state_c', 'is_init'] out_keys ['embed', ('next', 'recurrent_state_h'), ('next', 'recurrent_state_c')] .. GENERATED FROM PYTHON SOURCE LINES 258-271 We can see that these values contain the key we indicated as the in_key (and out_key) as well as recurrent key names. The out_keys are preceded by a "next" prefix that indicates that they will need to be written in the "next" TensorDict. We use this convention (which can be overridden by passing the in_keys/out_keys arguments) to make sure that a call to :func:`~torchrl.envs.utils.step_mdp` will move the recurrent state to the root TensorDict, making it available to the RNN during the following call (see figure in the intro). As mentioned earlier, we have one more optional transform to add to our environment to make sure that the recurrent states are passed to the buffer. The :meth:`~torchrl.modules.LSTMModule.make_tensordict_primer` method does exactly that: .. GENERATED FROM PYTHON SOURCE LINES 271-273 .. code-block:: Python env.append_transform(lstm.make_tensordict_primer()) .. rst-class:: sphx-glr-script-out .. code-block:: none TransformedEnv( env=GymEnv(env=CartPole-v1, batch_size=torch.Size([]), device=cpu), transform=Compose( ToTensorImage(keys=['pixels']), GrayScale(keys=['pixels']), Resize(w=84, h=84, interpolation=InterpolationMode.BILINEAR, keys=['pixels']), StepCounter(keys=[]), InitTracker(keys=[]), RewardScaling(loc=0.0000, scale=0.1000, keys=['reward']), ObservationNorm(keys=['pixels']), TensorDictPrimer(primers=CompositeSpec( recurrent_state_h: UnboundedContinuousTensorSpec( shape=torch.Size([1, 128]), space=None, device=cpu, dtype=torch.float32, domain=continuous), recurrent_state_c: UnboundedContinuousTensorSpec( shape=torch.Size([1, 128]), space=None, device=cpu, dtype=torch.float32, domain=continuous), device=cpu, shape=torch.Size([])), default_value={'recurrent_state_h': 0.0, 'recurrent_state_c': 0.0}, random=None))) .. GENERATED FROM PYTHON SOURCE LINES 274-276 and that's it! We can print the environment to check that everything looks good now that we have added the primer: .. GENERATED FROM PYTHON SOURCE LINES 276-278 .. code-block:: Python print(env) .. rst-class:: sphx-glr-script-out .. code-block:: none TransformedEnv( env=GymEnv(env=CartPole-v1, batch_size=torch.Size([]), device=cpu), transform=Compose( ToTensorImage(keys=['pixels']), GrayScale(keys=['pixels']), Resize(w=84, h=84, interpolation=InterpolationMode.BILINEAR, keys=['pixels']), StepCounter(keys=[]), InitTracker(keys=[]), RewardScaling(loc=0.0000, scale=0.1000, keys=['reward']), ObservationNorm(keys=['pixels']), TensorDictPrimer(primers=CompositeSpec( recurrent_state_h: UnboundedContinuousTensorSpec( shape=torch.Size([1, 128]), space=None, device=cpu, dtype=torch.float32, domain=continuous), recurrent_state_c: UnboundedContinuousTensorSpec( shape=torch.Size([1, 128]), space=None, device=cpu, dtype=torch.float32, domain=continuous), device=cpu, shape=torch.Size([])), default_value={'recurrent_state_h': 0.0, 'recurrent_state_c': 0.0}, random=None))) .. GENERATED FROM PYTHON SOURCE LINES 279-285 MLP ~~~ We use a single-layer MLP to represent the action values we'll be using for our policy. .. GENERATED FROM PYTHON SOURCE LINES 285-292 .. code-block:: Python mlp = MLP( out_features=2, num_cells=[ 64, ], device=device, ) .. GENERATED FROM PYTHON SOURCE LINES 293-294 and fill the bias with zeros: .. GENERATED FROM PYTHON SOURCE LINES 294-298 .. code-block:: Python mlp[-1].bias.data.fill_(0.0) mlp = Mod(mlp, in_keys=["embed"], out_keys=["action_value"]) .. GENERATED FROM PYTHON SOURCE LINES 299-310 Using the Q-Values to select an action ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ The last part of our policy is the Q-Value Module. The Q-Value module :class:`~torchrl.modules.tensordict_module.QValueModule` will read the ``"action_values"`` key that is produced by our MLP and from it, gather the action that has the maximum value. The only thing we need to do is to specify the action space, which can be done either by passing a string or an action-spec. This allows us to use Categorical (sometimes called "sparse") encoding or the one-hot version of it. .. GENERATED FROM PYTHON SOURCE LINES 310-312 .. code-block:: Python qval = QValueModule(action_space=env.action_spec) .. rst-class:: sphx-glr-script-out .. code-block:: pytb Traceback (most recent call last): File "/pytorch/rl/docs/source/reference/generated/tutorials/dqn_with_rnn.py", line 310, in qval = QValueModule(action_space=env.action_spec) File "/pytorch/rl/torchrl/modules/tensordict_module/actors.py", line 455, in __init__ raise TypeError("Using specs in action_space is deprecated") TypeError: Using specs in action_space is deprecated .. GENERATED FROM PYTHON SOURCE LINES 313-322 .. note:: TorchRL also provides a wrapper class :class:`torchrl.modules.QValueActor` that wraps a module in a Sequential together with a :class:`~torchrl.modules.tensordict_module.QValueModule` like we are doing explicitly here. There is little advantage to do this and the process is less transparent, but the end results will be similar to what we do here. We can now put things together in a :class:`~tensordict.nn.TensorDictSequential` .. GENERATED FROM PYTHON SOURCE LINES 322-324 .. code-block:: Python stoch_policy = Seq(feature, lstm, mlp, qval) .. GENERATED FROM PYTHON SOURCE LINES 325-331 DQN being a deterministic algorithm, exploration is a crucial part of it. We'll be using an :math:`\epsilon`-greedy policy with an epsilon of 0.2 decaying progressively to 0. This decay is achieved via a call to :meth:`~torchrl.modules.EGreedyModule.step` (see training loop below). .. GENERATED FROM PYTHON SOURCE LINES 331-339 .. code-block:: Python exploration_module = EGreedyModule( annealing_num_steps=1_000_000, spec=env.action_spec, eps_init=0.2 ) stoch_policy = TensorDictSequential( stoch_policy, exploration_module, ) .. GENERATED FROM PYTHON SOURCE LINES 340-354 Using the model for the loss ~~~~~~~~~~~~~~~~~~~~~~~~~~~~ The model as we've built it is well equipped to be used in sequential settings. However, the class :class:`torch.nn.LSTM` can use a cuDNN-optimized backend to run the RNN sequence faster on GPU device. We would not want to miss such an opportunity to speed up our training loop! To use it, we just need to tell the LSTM module to run on "recurrent-mode" when used by the loss. As we'll usually want to have two copies of the LSTM module, we do this by calling a :meth:`~torchrl.modules.LSTMModule.set_recurrent_mode` method that will return a new instance of the LSTM (with shared weights) that will assume that the input data is sequential in nature. .. GENERATED FROM PYTHON SOURCE LINES 354-356 .. code-block:: Python policy = Seq(feature, lstm.set_recurrent_mode(True), mlp, qval) .. GENERATED FROM PYTHON SOURCE LINES 357-360 Because we still have a couple of uninitialized parameters we should initialize them before creating an optimizer and such. .. GENERATED FROM PYTHON SOURCE LINES 360-362 .. code-block:: Python policy(env.reset()) .. GENERATED FROM PYTHON SOURCE LINES 363-374 DQN Loss -------- Out DQN loss requires us to pass the policy and, again, the action-space. While this may seem redundant, it is important as we want to make sure that the :class:`~torchrl.objectives.DQNLoss` and the :class:`~torchrl.modules.tensordict_module.QValueModule` classes are compatible, but aren't strongly dependent on each other. To use the Double-DQN, we ask for a ``delay_value`` argument that will create a non-differentiable copy of the network parameters to be used as a target network. .. GENERATED FROM PYTHON SOURCE LINES 374-376 .. code-block:: Python loss_fn = DQNLoss(policy, action_space=env.action_spec, delay_value=True) .. GENERATED FROM PYTHON SOURCE LINES 377-381 Since we are using a double DQN, we need to update the target parameters. We'll use a :class:`~torchrl.objectives.SoftUpdate` instance to carry out this work. .. GENERATED FROM PYTHON SOURCE LINES 381-385 .. code-block:: Python updater = SoftUpdate(loss_fn, eps=0.95) optim = torch.optim.Adam(policy.parameters(), lr=3e-4) .. GENERATED FROM PYTHON SOURCE LINES 386-401 Collector and replay buffer --------------------------- We build the simplest data collector there is. We'll try to train our algorithm with a million frames, extending the buffer with 50 frames at a time. The buffer will be designed to store 20 thousands trajectories of 50 steps each. At each optimization step (16 per data collection), we'll collect 4 items from our buffer, for a total of 200 transitions. We'll use a :class:`~torchrl.data.replay_buffers.LazyMemmapStorage` storage to keep the data on disk. .. note:: For the sake of efficiency, we're only running a few thousands iterations here. In a real setting, the total number of frames should be set to 1M. .. GENERATED FROM PYTHON SOURCE LINES 401-406 .. code-block:: Python collector = SyncDataCollector(env, stoch_policy, frames_per_batch=50, total_frames=200) rb = TensorDictReplayBuffer( storage=LazyMemmapStorage(20_000), batch_size=4, prefetch=10 ) .. GENERATED FROM PYTHON SOURCE LINES 407-413 Training loop ------------- To keep track of the progress, we will run the policy in the environment once every 50 data collection, and plot the results after training. .. GENERATED FROM PYTHON SOURCE LINES 413-449 .. code-block:: Python utd = 16 pbar = tqdm.tqdm(total=1_000_000) longest = 0 traj_lens = [] for i, data in enumerate(collector): if i == 0: print( "Let us print the first batch of data.\nPay attention to the key names " "which will reflect what can be found in this data structure, in particular: " "the output of the QValueModule (action_values, action and chosen_action_value)," "the 'is_init' key that will tell us if a step is initial or not, and the " "recurrent_state keys.\n", data, ) pbar.update(data.numel()) # it is important to pass data that is not flattened rb.extend(data.unsqueeze(0).to_tensordict().cpu()) for _ in range(utd): s = rb.sample().to(device, non_blocking=True) loss_vals = loss_fn(s) loss_vals["loss"].backward() optim.step() optim.zero_grad() longest = max(longest, data["step_count"].max().item()) pbar.set_description( f"steps: {longest}, loss_val: {loss_vals['loss'].item(): 4.4f}, action_spread: {data['action'].sum(0)}" ) exploration_module.step(data.numel()) updater.step() with set_exploration_type(ExplorationType.MODE), torch.no_grad(): rollout = env.rollout(10000, stoch_policy) traj_lens.append(rollout.get(("next", "step_count")).max().item()) .. GENERATED FROM PYTHON SOURCE LINES 450-452 Let's plot our results: .. GENERATED FROM PYTHON SOURCE LINES 452-459 .. code-block:: Python if traj_lens: from matplotlib import pyplot as plt plt.plot(traj_lens) plt.xlabel("Test collection") plt.title("Test trajectory lengths") .. GENERATED FROM PYTHON SOURCE LINES 460-478 Conclusion ---------- We have seen how an RNN can be incorporated in a policy in TorchRL. You should now be able: - Create an LSTM module that acts as a :class:`~tensordict.nn.TensorDictModule` - Indicate to the LSTM module that a reset is needed via an :class:`~torchrl.envs.transforms.InitTracker` transform - Incorporate this module in a policy and in a loss module - Make sure that the collector is made aware of the recurrent state entries such that they can be stored in the replay buffer along with the rest of the data Further Reading --------------- - The TorchRL documentation can be found `here `_. .. rst-class:: sphx-glr-timing **Total running time of the script:** (0 minutes 37.175 seconds) **Estimated memory usage:** 4059 MB .. _sphx_glr_download_tutorials_dqn_with_rnn.py: .. only:: html .. container:: sphx-glr-footer sphx-glr-footer-example .. container:: sphx-glr-download sphx-glr-download-jupyter :download:`Download Jupyter notebook: dqn_with_rnn.ipynb ` .. container:: sphx-glr-download sphx-glr-download-python :download:`Download Python source code: dqn_with_rnn.py ` .. only:: html .. rst-class:: sphx-glr-signature `Gallery generated by Sphinx-Gallery `_