fix bug in augment_dataset_quantile_stats.py that was not detecting… (#2106)

* fix bug in `augment_dataset_quantile_stats.py` that was not detecting the image features because we were looping over hf_dataset. Now we loop over the dataset itself

* Update src/lerobot/datasets/v30/augment_dataset_quantile_stats.py

Signed-off-by: Michel Aractingi <michel.aractingi@huggingface.co>

---------

Signed-off-by: Michel Aractingi <michel.aractingi@huggingface.co>
Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

src/lerobot/datasets/v30/augment_dataset_quantile_stats.py

@@ -40,10 +40,12 @@ from pathlib import Path
 
 import numpy as np
 import torch
+from huggingface_hub import HfApi
+from requests import HTTPError
 from tqdm import tqdm
 
 from lerobot.datasets.compute_stats import DEFAULT_QUANTILES, aggregate_stats, get_feature_stats
-from lerobot.datasets.lerobot_dataset import LeRobotDataset
+from lerobot.datasets.lerobot_dataset import CODEBASE_VERSION, LeRobotDataset
 from lerobot.datasets.utils import write_stats
 from lerobot.utils.utils import init_logging
 
@@ -85,13 +87,27 @@ def process_single_episode(dataset: LeRobotDataset, episode_idx: int) -> dict:
     start_idx = dataset.meta.episodes[episode_idx]["dataset_from_index"]
     end_idx = dataset.meta.episodes[episode_idx]["dataset_to_index"]
 
+    collected_data: dict[str, list] = {}
+    for idx in range(start_idx, end_idx):
+        item = dataset[idx]
+        for key, value in item.items():
+            if key not in dataset.features:
+                continue
+
+            if key not in collected_data:
+                collected_data[key] = []
+            collected_data[key].append(value)
+
     ep_stats = {}
-    for key, data in dataset.hf_dataset[start_idx:end_idx].items():
+    for key, data_list in collected_data.items():
         if dataset.features[key]["dtype"] == "string":
             continue
 
-        data = torch.stack(data).cpu().numpy()
+        data = torch.stack(data_list).cpu().numpy()
         if dataset.features[key]["dtype"] in ["image", "video"]:
+            if data.dtype == np.uint8:
+                data = data.astype(np.float32) / 255.0
+
             axes_to_reduce = (0, 2, 3)
             keepdims = True
         else:
@@ -103,12 +119,9 @@ def process_single_episode(dataset: LeRobotDataset, episode_idx: int) -> dict:
         )
 
         if dataset.features[key]["dtype"] in ["image", "video"]:
-            for k, v in ep_stats[key].items():
-                if dataset.features[key]["dtype"] == "video":
-                    v = v / 255.0
-                if k != "count":
-                    v = np.squeeze(v, axis=0)
-                ep_stats[key][k] = v
+            ep_stats[key] = {
+                k: v if k == "count" else np.squeeze(v, axis=0) for k, v in ep_stats[key].items()
+            }
 
     return ep_stats
 
@@ -121,25 +134,39 @@ def compute_quantile_stats_for_dataset(dataset: LeRobotDataset) -> dict[str, dic
 
     Returns:
         Dictionary containing aggregated statistics with quantiles
+
+    Note:
+        Video decoding operations are not thread-safe, so we process episodes sequentially
+        when video keys are present. For datasets without videos, we use parallel processing
+        with ThreadPoolExecutor for better performance.
     """
     logging.info(f"Computing quantile statistics for dataset with {dataset.num_episodes} episodes")
 
     episode_stats_list = []
-    max_workers = min(dataset.num_episodes, 16)
+    has_videos = len(dataset.meta.video_keys) > 0
 
-    with concurrent.futures.ThreadPoolExecutor(max_workers=max_workers) as executor:
-        future_to_episode = {
-            executor.submit(process_single_episode, dataset, episode_idx): episode_idx
-            for episode_idx in range(dataset.num_episodes)
-        }
+    if has_videos:
+        logging.info("Dataset contains video keys - using sequential processing for thread safety")
+        for episode_idx in tqdm(range(dataset.num_episodes), desc="Processing episodes"):
+            ep_stats = process_single_episode(dataset, episode_idx)
+            episode_stats_list.append(ep_stats)
+    else:
+        logging.info("Dataset has no video keys - using parallel processing for better performance")
+        max_workers = min(dataset.num_episodes, 16)
 
-        episode_results = {}
-        with tqdm(total=dataset.num_episodes, desc="Processing episodes") as pbar:
-            for future in concurrent.futures.as_completed(future_to_episode):
-                episode_idx = future_to_episode[future]
-                ep_stats = future.result()
-                episode_results[episode_idx] = ep_stats
-                pbar.update(1)
+        with concurrent.futures.ThreadPoolExecutor(max_workers=max_workers) as executor:
+            future_to_episode = {
+                executor.submit(process_single_episode, dataset, episode_idx): episode_idx
+                for episode_idx in range(dataset.num_episodes)
+            }
+
+            episode_results = {}
+            with tqdm(total=dataset.num_episodes, desc="Processing episodes") as pbar:
+                for future in concurrent.futures.as_completed(future_to_episode):
+                    episode_idx = future_to_episode[future]
+                    ep_stats = future.result()
+                    episode_results[episode_idx] = ep_stats
+                    pbar.update(1)
 
         for episode_idx in range(dataset.num_episodes):
             if episode_idx in episode_results:
@@ -186,6 +213,14 @@ def augment_dataset_with_quantile_stats(
     logging.info("Successfully updated dataset with quantile statistics")
     dataset.push_to_hub()
 
+    hub_api = HfApi()
+    try:
+        hub_api.delete_tag(repo_id, tag=CODEBASE_VERSION, repo_type="dataset")
+    except HTTPError as e:
+        logging.info(f"tag={CODEBASE_VERSION} probably doesn't exist. Skipping exception ({e})")
+        pass
+    hub_api.create_tag(repo_id, tag=CODEBASE_VERSION, revision=None, repo_type="dataset")
+
 
 def main():
     """Main function to run the augmentation script."""