Add API Examples (#2289)

* (unscrewing things up) (#2288)

* fix: expose a function explicitly building a frame for inference

* fix: first make dataset frame, then make ready for inference

* fix: reducing reliance on lerobot record for policy's ouptuts too

* fix: encapsulating squeezing out + device handling from predict action

* fix: remove duplicated call to build_inference_frame and add a function to only perform data type handling (whole conversion is: keys matching + data type conversion)

* refactor(envs): add custom-observation-size (#2167)

* fix: add MockMotorBus to MockRobot

* rl: first drafts

* add: all components of HIL SERL

* fix: actor block works

* fix: less friction, less friction

* add: hil-serl complete example

* fix: dataset names

* fix: restructuring example folder

* fix: act works but found bug in how ACT works

* fix: same path for both pre and postprocessors

* fix: paths

* add: example usage for act

* add: using ACT example

* fix: training examples

* fix: using examples

* fix: camera index

* fix: rename workflows into tutorial so that the path of the files is lerobot/examples/tutorial/...

* fix: upload everything in one repo

* fix: model name

* fix: simplify model path

* add: VLAs example

---------

Signed-off-by: Francesco Capuano <74058581+fracapuano@users.noreply.github.com>

* fix: minor fix using named attributes

* fix: change model to act

* fix: named attributes for inference frame building

* fix: minor fixes to smolvla

* fix: small changes to pi0

* remove: old file that should have never been committed (ups sorry sorry)

---------

Signed-off-by: Francesco Capuano <74058581+fracapuano@users.noreply.github.com>

examples/tutorial/diffusion/diffusion_using_example.py

@@ -0,0 +1,60 @@
+import torch
+
+from lerobot.cameras.opencv.configuration_opencv import OpenCVCameraConfig
+from lerobot.datasets.lerobot_dataset import LeRobotDatasetMetadata
+from lerobot.policies.diffusion.modeling_diffusion import DiffusionPolicy
+from lerobot.policies.factory import make_pre_post_processors
+from lerobot.policies.utils import build_inference_frame, make_robot_action
+from lerobot.robots.so100_follower.config_so100_follower import SO100FollowerConfig
+from lerobot.robots.so100_follower.so100_follower import SO100Follower
+
+device = torch.device("mps")  # or "cuda" or "cpu"
+model_id = "fracapuano/robot_learning_tutorial_diffusion"
+
+model = DiffusionPolicy.from_pretrained(model_id)
+
+dataset_id = "lerobot/svla_so101_pickplace"
+# This only downloads the metadata for the dataset, ~10s of MB even for large-scale datasets
+dataset_metadata = LeRobotDatasetMetadata(dataset_id)
+preprocess, postprocess = make_pre_post_processors(
+    model.config, model_id, dataset_stats=dataset_metadata.stats
+)
+
+MAX_EPISODES = 5
+MAX_STEPS_PER_EPISODE = 20
+
+
+# # find ports using lerobot-find-port
+follower_port = ...  # something like "/dev/tty.usbmodem58760431631"
+
+# # the robot ids are used the load the right calibration files
+follower_id = ...  # something like "follower_so100"
+
+# Robot and environment configuration
+# Camera keys must match the name and resolutions of the ones used for training!
+# You can check the camera keys expected by a model in the info.json card on the model card on the Hub
+camera_config = {
+    "side": OpenCVCameraConfig(index_or_path=0, width=640, height=480, fps=30),
+    "up": OpenCVCameraConfig(index_or_path=1, width=640, height=480, fps=30),
+}
+
+robot_cfg = SO100FollowerConfig(port=follower_port, id=follower_id, cameras=camera_config)
+robot = SO100Follower(robot_cfg)
+robot.connect()
+
+
+for _ in range(MAX_EPISODES):
+    for _ in range(MAX_STEPS_PER_EPISODE):
+        obs = robot.get_observation()
+        obs_frame = build_inference_frame(
+            observation=obs, ds_features=dataset_metadata.features, device=device
+        )
+
+        obs = preprocess(obs_frame)
+
+        action = model.select_action(obs)
+        action = postprocess(action)
+        action = make_robot_action(action, dataset_metadata.features)
+        robot.send_action(action)
+
+    print("Episode finished! Starting new episode...")