feat(envs): add envs pre-post processor (#2474)

* more changes

* working changes

* more changes

* more fixes

* fix style

* more

* clean

* put axis-1

* more fixes

* more styling fixes:

* iterate on review:

* more changes

* add env processor

* style

* more changes

* add docs

* fix imports

* fix test, add to train

* Update src/lerobot/envs/factory.py

Co-authored-by: Michel Aractingi <michel.aractingi@huggingface.co>
Signed-off-by: Jade Choghari <chogharijade@gmail.com>

* iterate on review

---------

Signed-off-by: Jade Choghari <chogharijade@gmail.com>
Co-authored-by: jade.choghari@huggingface.co <“chogharijade@gmail.com”>
Co-authored-by: Michel Aractingi <michel.aractingi@huggingface.co>

src/lerobot/scripts/lerobot_train.py

@@ -29,7 +29,7 @@ from lerobot.configs.train import TrainPipelineConfig
 from lerobot.datasets.factory import make_dataset
 from lerobot.datasets.sampler import EpisodeAwareSampler
 from lerobot.datasets.utils import cycle
-from lerobot.envs.factory import make_env
+from lerobot.envs.factory import make_env, make_env_pre_post_processors
 from lerobot.envs.utils import close_envs
 from lerobot.optim.factory import make_optimizer_and_scheduler
 from lerobot.policies.factory import make_policy, make_pre_post_processors
@@ -259,6 +259,8 @@ def train(cfg: TrainPipelineConfig, accelerator: Accelerator | None = None):
         logging.info(colored("Output dir:", "yellow", attrs=["bold"]) + f" {cfg.output_dir}")
         if cfg.env is not None:
             logging.info(f"{cfg.env.task=}")
+            logging.info("Creating environment processors")
+            env_preprocessor, env_postprocessor = make_env_pre_post_processors(env_cfg=cfg.env)
         logging.info(f"{cfg.steps=} ({format_big_number(cfg.steps)})")
         logging.info(f"{dataset.num_frames=} ({format_big_number(dataset.num_frames)})")
         logging.info(f"{dataset.num_episodes=}")
@@ -385,6 +387,8 @@ def train(cfg: TrainPipelineConfig, accelerator: Accelerator | None = None):
                     eval_info = eval_policy_all(
                         envs=eval_env,  # dict[suite][task_id] -> vec_env
                         policy=accelerator.unwrap_model(policy),
+                        env_preprocessor=env_preprocessor,
+                        env_postprocessor=env_postprocessor,
                         preprocessor=preprocessor,
                         postprocessor=postprocessor,
                         n_episodes=cfg.eval.n_episodes,