[Doc] Tutorial revamp (#926)

Author: vmoens

.github/workflows/docs.yml

@@ -85,7 +85,7 @@ jobs:
     - name: Get output time
       run: echo "The time was ${{ steps.build.outputs.time }}"
     - name: Deploy
-      if: ${{ github.ref == 'refs/heads/main' }}
+      if: ${{ github.ref == 'refs/heads/main' || github.event_name == 'workflow_dispatch' }}
       uses: JamesIves/github-pages-deploy-action@releases/v4
       with:
           token: ${{ secrets.GITHUB_TOKEN }}

docs/source/_static/img/cartpole.gif

@@ -367,10 +367,9 @@ def _init(self, data: Union[TensorDictBase, torch.Tensor]) -> None:
             )
         elif is_tensorclass(data):
             out = (
-                data.expand(self.max_size, *data.shape)
-                .clone()
-                .zero_()
-                .memmap_(prefix=self.scratch_dir)
+                data.clone()
+                .expand(self.max_size, *data.shape)
+                .memmap_like(prefix=self.scratch_dir)
                 .to(self.device)
             )
             for key, tensor in sorted(
@@ -384,10 +383,9 @@ def _init(self, data: Union[TensorDictBase, torch.Tensor]) -> None:
             # out = TensorDict({}, [self.max_size, *data.shape])
             print("The storage is being created: ")
             out = (
-                data.expand(self.max_size, *data.shape)
-                .to_tensordict()
-                .zero_()
-                .memmap_(prefix=self.scratch_dir)
+                data.clone()
+                .expand(self.max_size, *data.shape)
+                .memmap_like(prefix=self.scratch_dir)
                 .to(self.device)
             )
             for key, tensor in sorted(

docs/source/_static/img/cartpole_demo.gif

@@ -584,23 +584,24 @@ def _assert_tensordict_shape(self, tensordict: TensorDictBase) -> None:
                 f"got {tensordict.batch_size} and {self.batch_size}"
             )
 
-    def rand_step(self, tensordict: Optional[TensorDictBase] = None) -> TensorDictBase:
-        """Performs a random step in the environment given the action_spec attribute.
+    def rand_action(self, tensordict: Optional[TensorDictBase] = None):
+        """Performs a random action given the action_spec attribute.
 
         Args:
-            tensordict (TensorDictBase, optional): tensordict where the resulting info should be written.
+            tensordict (TensorDictBase, optional): tensordict where the resulting action should be written.
 
         Returns:
-            a tensordict object with the new observation after a random step in the environment. The action will
-            be stored with the "action" key.
+            a tensordict object with the "action" entry updated with a random
+            sample from the action-spec.
 
         """
         shape = torch.Size([])
         if tensordict is None:
             tensordict = TensorDict(
                 {}, device=self.device, batch_size=self.batch_size, _run_checks=False
             )
-        elif not self.batch_locked and not self.batch_size:
+
+        if not self.batch_locked and not self.batch_size:
             shape = tensordict.shape
         elif not self.batch_locked and tensordict.shape != self.batch_size:
             raise RuntimeError(
@@ -611,6 +612,20 @@ def rand_step(self, tensordict: Optional[TensorDictBase] = None) -> TensorDictBa
             )
         action = self.action_spec.rand(shape)
         tensordict.set("action", action)
+        return tensordict
+
+    def rand_step(self, tensordict: Optional[TensorDictBase] = None) -> TensorDictBase:
+        """Performs a random step in the environment given the action_spec attribute.
+
+        Args:
+            tensordict (TensorDictBase, optional): tensordict where the resulting info should be written.
+
+        Returns:
+            a tensordict object with the new observation after a random step in the environment. The action will
+            be stored with the "action" key.
+
+        """
+        tensordict = self.rand_action(tensordict)
         return self.step(tensordict)
 
     @property
@@ -680,7 +695,7 @@ def rollout(
         if policy is None:
 
             def policy(td):
-                self.rand_step(td)
+                self.rand_action(td)
                 return td
 
         tensordicts = []
@@ -796,16 +811,18 @@ def to(self, device: DEVICE_TYPING) -> EnvBase:
     def fake_tensordict(self) -> TensorDictBase:
         """Returns a fake tensordict with key-value pairs that match in shape, device and dtype what can be expected during an environment rollout."""
         input_spec = self.input_spec
-        fake_input = input_spec.zero()
         observation_spec = self.observation_spec
         fake_obs = observation_spec.zero()
+        fake_input = input_spec.zero()
+        # the input and output key may match, but the output prevails
+        # Hence we generate the input, and override using the output
+        fake_in_out = fake_input.clone().update(fake_obs)
         reward_spec = self.reward_spec
         fake_reward = reward_spec.zero()
         fake_td = TensorDict(
             {
-                **fake_obs,
+                **fake_in_out,
                 "next": fake_obs.clone(),
-                **fake_input,
                 "reward": fake_reward,
                 "done": torch.zeros(
                     (*self.batch_size, 1), dtype=torch.bool, device=self.device