remove the sampler cause the relative index is added (#2521)

Co-authored-by: Michel Aractingi <michel.aractingi@huggingface.co>

src/lerobot/scripts/lerobot_dataset_viz.py

@@ -65,7 +65,6 @@ import argparse
 import gc
 import logging
 import time
-from collections.abc import Iterator
 from pathlib import Path
 
 import numpy as np
@@ -78,19 +77,6 @@ from lerobot.datasets.lerobot_dataset import LeRobotDataset
 from lerobot.utils.constants import ACTION, DONE, OBS_STATE, REWARD
 
 
-class EpisodeSampler(torch.utils.data.Sampler):
-    def __init__(self, dataset: LeRobotDataset, episode_index: int):
-        from_idx = dataset.meta.episodes["dataset_from_index"][episode_index]
-        to_idx = dataset.meta.episodes["dataset_to_index"][episode_index]
-        self.frame_ids = range(from_idx, to_idx)
-
-    def __iter__(self) -> Iterator:
-        return iter(self.frame_ids)
-
-    def __len__(self) -> int:
-        return len(self.frame_ids)
-
-
 def to_hwc_uint8_numpy(chw_float32_torch: torch.Tensor) -> np.ndarray:
     assert chw_float32_torch.dtype == torch.float32
     assert chw_float32_torch.ndim == 3
@@ -119,12 +105,10 @@ def visualize_dataset(
     repo_id = dataset.repo_id
 
     logging.info("Loading dataloader")
-    episode_sampler = EpisodeSampler(dataset, episode_index)
     dataloader = torch.utils.data.DataLoader(
         dataset,
         num_workers=num_workers,
         batch_size=batch_size,
-        sampler=episode_sampler,
     )
 
     logging.info("Starting Rerun")