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Jade Choghari 32fc5504cc add various experiments for wavelet 2026-02-13 10:27:02 +00:00
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# Action tokenizer benchmark
## Questions
What is the trade-off between:
- **Compression**: how many tokens are needed to represent an action chunk (e.g. horizon × action_dim floats)?
- **Reconstruction quality**: how well does encode-then-decode preserve the original actions?
- **Speed**: how long does encoding and decoding take per chunk?
How to choose an action tokenizer?
- Which tokenizer architecture (e.g. dct + BPE, DCT + BPE)?
- Which **action horizon** and **encoded dimensions** to use?
- Which **normalization** (QUANTILES, MEAN_STD, MIN_MAX) and **delta transform** (relative vs absolute actions)?
- How do reconstruction error and compression ratio vary across datasets and tokenizer settings?
This benchmark loads action chunks from a LeRobot dataset using the same pipeline as `lerobot-train-tokenizer`, runs a trained action tokenizer in encode/decode mode, and reports reconstruction error, compression stats, and timing. Results are saved as JSON under `outputs/` for comparison and analysis.
## Variables
**Dataset & chunking**
- **repo_id**: LeRobot dataset (e.g. `lerobot/pusht`). Action statistics and normalization are taken from the dataset metadata when available.
- **action_horizon**: Number of future steps per action chunk (must match the tokenizers training).
- **encoded_dims**: Dimension ranges to encode (e.g. `0:6` or `0:6,7:14`). Must match the tokenizer.
- **max_episodes**: Cap on episodes to load (default: all).
- **sample_fraction**: Fraction of chunks to sample per episode (default `0.2`) to keep runtime manageable.
**Transform & normalization**
- **normalization_mode**: `IDENTITY`, `MEAN_STD`, `MIN_MAX`, `QUANTILES`, `QUANTILE10`. Should match the tokenizers training.
- **delta_dims**: Comma-separated dimension indices for delta (relative) transform.
- **use_delta_transform**: Whether to convert actions to relative to current state for those dimensions.
- **state_key**: Dataset key for state (e.g. `observation.state`) used when applying delta transform.
**Tokenizer & evaluation**
- **action_tokenizer_path**: Path or HuggingFace repo id of the trained tokenizer (e.g. `outputs/wavetoken`).
- **max_chunks_for_reconstruction**: Max number of chunks to use for reconstruction and timing (default `500`) to limit runtime.
### Main parameters
| parameter | default | description |
| -------------------------------- | ---------------------------- | ------------------------------------------------ |
| **action_tokenizer_path** | (required) | Path or Hub id of the trained action tokenizer. |
| **repo_id** | (required) | LeRobot dataset repo id. |
| **action_horizon** | `10` | Future steps per chunk. |
| **encoded_dims** | `0:6` | Dimension ranges to encode (e.g. `0:6,7:14`). |
| **normalization_mode** | `QUANTILES` | Normalization mode for actions. |
| **max_episodes** | all | Max episodes to load. |
| **sample_fraction** | `0.2` | Fraction of chunks sampled per episode. |
| **max_chunks_for_reconstruction**| `500` | Chunks used for reconstruction and timing. |
| **output_dir** | `outputs/action_tokenizer_benchmark` | Directory for results JSON. |
## Metrics
**Reconstruction (lower is better)**
- **reconstruction_mae**: Mean absolute error between original and decoded action chunks.
- **reconstruction_mse**: Mean squared error.
- **reconstruction_rmse**: Root mean squared error.
- **reconstruction_max_abs_error**: Maximum absolute error over all dimensions and samples.
- **per_dimension_mae**: MAE per action dimension (list of length `action_dim`).
**Compression**
- **compression_ratio**: Ratio (action_horizon × action_dim) / mean number of tokens. Higher means more compression.
- **mean_token_length**, **std_token_length**: Mean and standard deviation of token count per chunk.
- **min_token_length**, **max_token_length**: Min and max token count.
- **p50_token_length**, **p99_token_length**: 50th and 99th percentile token counts.
**Timing (seconds per chunk)**
- **mean_encode_time_sec**: Mean time to encode one chunk.
- **mean_decode_time_sec**: Mean time to decode one chunk.
The JSON output also includes **num_chunks_evaluated** and **total_chunks_available** for context.
## How the benchmark works
1. **Load dataset**: LeRobot dataset is loaded for the given `repo_id` and `root`.
2. **Build action chunks**: For each episode (up to `max_episodes`), action chunks are built with the same logic as `lerobot-train-tokenizer`: sliding window of length `action_horizon`, optional delta transform, and per-episode sampling with `sample_fraction`.
3. **Extract and normalize**: Only `encoded_dims` are kept. Normalization is applied using the datasets action stats when available, according to `normalization_mode`.
4. **Encode / decode**: A random sample of chunks (size `max_chunks_for_reconstruction`) is encoded and then decoded with the tokenizer. Encode and decode times are recorded per chunk.
5. **Compute metrics**: Reconstruction metrics are computed between original and decoded chunks; compression and timing stats are aggregated.
6. **Save results**: A JSON file is written to `output_dir` with name `{timestamp}_{repo_id}_action_tokenizer_results.json`, containing the full config and all metrics.
The pipeline (chunking, dimensions, normalization, delta) must match how the tokenizer was trained; otherwise reconstruction error can be large or the tokenizer may raise.
## Caveats
- The tokenizers **action_horizon** and **action_dim** (and optionally DCT settings) are fixed at training time. The benchmark infers dimensions from the dataset and encoded dims; the tokenizer path must correspond to a model trained with the same horizon and encoded dimensions.
- Reconstruction is evaluated in **normalized space** (the same space the tokenizer sees). For interpretation in raw action space, you would need to invert normalization outside this script.
- Only one tokenizer and one dataset are evaluated per run. To compare tokenizers or datasets, run the script multiple times and compare the saved JSON files.
## Example
Quick run with a local tokenizer and a small number of episodes:
```bash
python benchmarks/tokens/run_action_tokenizer_benchmark.py \
--action-tokenizer-path=outputs/wavetoken \
--repo-id=lerobot/pusht \
--action-horizon=10 \
--max-episodes=50 \
--output-dir=outputs/action_tokenizer_benchmark
```
With delta transform and custom encoded dimensions:
```bash
python benchmarks/tokens/run_action_tokenizer_benchmark.py \
--action-tokenizer-path=outputs/wavetoken \
--repo-id=lerobot/pusht \
--action-horizon=10 \
--encoded-dims=0:6,7:14 \
--delta-dims=0,1,2,3,4,5 \
--use-delta-transform \
--normalization-mode=QUANTILES \
--max-chunks-for-reconstruction=500 \
--output-dir=outputs/action_tokenizer_benchmark
```
Results are written to e.g. `outputs/action_tokenizer_benchmark/2026-02-12_14-30-00_lerobot_pusht_action_tokenizer_results.json`.
## Results
Results are stored as JSON in the directory given by `--output-dir` (default: `outputs/action_tokenizer_benchmark`). Each file contains:
- **config**: All script arguments (tokenizer path, repo_id, action_horizon, encoded_dims, normalization_mode, etc.) for reproducibility.
- **metrics**: All reconstruction, compression, and timing metrics described above.
To compare runs, load and diff or aggregate these JSON files with your own scripts or notebooks.
@@ -0,0 +1,442 @@
#!/usr/bin/env python
# Copyright 2026 The HuggingFace Inc. team. All rights reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
"""Benchmark action tokenization: reconstruction error, compression ratio, and timing.
Loads action chunks from a LeRobot dataset, encodes/decodes them with a trained action
tokenizer, and reports:
- Reconstruction: MAE, MSE, RMSE, max absolute error, per-dimension MAE
- Jerk: mean absolute jerk (original and reconstructed), jerk reconstruction MAE
- Compression: ratio (input size / mean tokens), token length stats
- Timing: mean encode/decode time per chunk
Results are saved to outputs/action_tokenizer_benchmark/<timestamp>_results.json.
Example:
```bash
python benchmarks/tokens/run_action_tokenizer_benchmark.py \
--action-tokenizer-path=outputs/wavetoken \
--repo-id=lerobot/pusht \
--action-horizon=10 \
--max-episodes=50 \
--output-dir=outputs/action_tokenizer_benchmark
```
"""
import argparse
import json
import time
from pathlib import Path
import numpy as np
from lerobot.configs.types import NormalizationMode
from lerobot.datasets.lerobot_dataset import LeRobotDataset
from lerobot.utils.constants import ACTION, OBS_STATE
# Optional: use same helpers as train script if we want to avoid duplication
from lerobot.scripts.lerobot_train_tokenizer import (
apply_normalization,
process_episode,
)
def load_action_chunks(
repo_id: str,
root: str | None,
action_horizon: int,
max_episodes: int | None,
sample_fraction: float,
encoded_dims: str,
delta_dims: str | None,
use_delta_transform: bool,
state_key: str,
normalization_mode: NormalizationMode,
):
"""Load and normalize action chunks from a LeRobot dataset (same pipeline as training)."""
dataset = LeRobotDataset(repo_id=repo_id, root=root)
num_episodes = dataset.num_episodes
if max_episodes is not None:
num_episodes = min(max_episodes, num_episodes)
# Parse encoded dims
encoded_dim_ranges = []
for range_str in encoded_dims.split(","):
start, end = map(int, range_str.strip().split(":"))
encoded_dim_ranges.append((start, end))
total_encoded_dims = sum(end - start for start, end in encoded_dim_ranges)
delta_dim_list = None
if delta_dims is not None and delta_dims.strip():
delta_dim_list = [int(d.strip()) for d in delta_dims.split(",")]
all_chunks = []
for ep_idx in range(num_episodes):
chunks = process_episode(
(
dataset,
ep_idx,
action_horizon,
delta_dim_list,
sample_fraction,
state_key,
use_delta_transform,
)
)
if chunks is not None:
all_chunks.append(chunks)
if not all_chunks:
raise ValueError("No action chunks collected. Check action_horizon and dataset.")
all_chunks = np.concatenate(all_chunks, axis=0)
# Extract encoded dimensions only
encoded_chunks = []
for start, end in encoded_dim_ranges:
encoded_chunks.append(all_chunks[:, :, start:end])
encoded_chunks = np.concatenate(encoded_chunks, axis=-1)
# Normalize
norm_stats = dataset.meta.stats
if norm_stats is not None and ACTION in norm_stats:
action_stats = norm_stats[ACTION]
encoded_dim_indices = []
for start, end in encoded_dim_ranges:
encoded_dim_indices.extend(range(start, end))
encoded_dim_indices = np.array(encoded_dim_indices)
encoded_stats = {}
for stat_name, stat_values in action_stats.items():
if isinstance(stat_values, (list, np.ndarray)):
stat_array = np.array(stat_values)
if len(stat_array) > max(encoded_dim_indices):
encoded_stats[stat_name] = stat_array[encoded_dim_indices]
if encoded_stats:
try:
encoded_chunks = apply_normalization(
encoded_chunks, encoded_stats, normalization_mode, eps=1e-8
)
except ValueError:
pass
return encoded_chunks, total_encoded_dims, action_horizon, dataset.repo_id
def compute_reconstruction_metrics(original: np.ndarray, reconstructed: np.ndarray):
"""Compute reconstruction error metrics (original and reconstructed same shape [N, T, D])."""
diff = reconstructed - original
mae = float(np.mean(np.abs(diff)))
mse = float(np.mean(diff**2))
rmse = float(np.sqrt(mse))
max_abs_err = float(np.max(np.abs(diff)))
# Per-dimension MAE (over N and T)
per_dim_mae = np.mean(np.abs(diff), axis=(0, 1))
per_dim_mae = per_dim_mae.tolist()
return {
"reconstruction_mae": mae,
"reconstruction_mse": mse,
"reconstruction_rmse": rmse,
"reconstruction_max_abs_error": max_abs_err,
"per_dimension_mae": per_dim_mae,
}
def compute_jerk_metrics(original: np.ndarray, reconstructed: np.ndarray) -> dict:
"""Compute jerk (3rd derivative of action w.r.t. time) metrics.
Args:
original: Action chunks [N, T, D].
reconstructed: Reconstructed action chunks [N, T, D].
Returns:
Dict with mean absolute jerk for original, reconstructed, and jerk reconstruction MAE.
"""
# Jerk = 3rd discrete difference along time axis; need T >= 4
if original.shape[1] < 4:
return {}
jerk_orig = np.diff(original, n=3, axis=1) # (N, T-3, D)
jerk_recon = np.diff(reconstructed, n=3, axis=1)
mae_jerk_orig = float(np.mean(np.abs(jerk_orig)))
mae_jerk_recon = float(np.mean(np.abs(jerk_recon)))
jerk_reconstruction_mae = float(np.mean(np.abs(jerk_recon - jerk_orig)))
return {
"jerk_mae_original": mae_jerk_orig,
"jerk_mae_reconstructed": mae_jerk_recon,
"jerk_reconstruction_mae": jerk_reconstruction_mae,
}
def run_benchmark(
action_chunks: np.ndarray,
action_horizon: int,
action_dim: int,
tokenizer_path: str,
max_chunks_for_reconstruction: int | None = 500,
):
"""Encode/decode action chunks and compute metrics."""
from transformers import AutoProcessor
processor = AutoProcessor.from_pretrained(tokenizer_path, trust_remote_code=True)
n_chunks = len(action_chunks)
sample_size = n_chunks
if max_chunks_for_reconstruction is not None:
sample_size = min(max_chunks_for_reconstruction, n_chunks)
rng = np.random.RandomState(42)
indices = rng.choice(n_chunks, size=sample_size, replace=False)
sample_chunks = action_chunks[indices]
# Encode
token_lengths = []
encode_times = []
all_tokens = []
for i in range(len(sample_chunks)):
chunk = sample_chunks[i : i + 1]
t0 = time.perf_counter()
tokens = processor(chunk)[0]
encode_times.append(time.perf_counter() - t0)
if isinstance(tokens, list):
token_lengths.append(len(tokens))
all_tokens.append(tokens)
else:
n = tokens.shape[0] if hasattr(tokens, "shape") else len(tokens)
token_lengths.append(n)
all_tokens.append(tokens.tolist() if hasattr(tokens, "tolist") else list(tokens))
# Decode (processor keeps time_horizon/action_dim from encode)
decoded_list = []
decode_times = []
for i, tok_list in enumerate(all_tokens):
t0 = time.perf_counter()
recon = processor.decode(
[tok_list],
time_horizon=action_horizon,
action_dim=action_dim,
)
decode_times.append(time.perf_counter() - t0)
decoded_list.append(recon)
decoded = np.concatenate(decoded_list, axis=0)
# Reconstruction metrics
metrics = compute_reconstruction_metrics(sample_chunks, decoded)
# Jerk metrics (3rd derivative along time)
jerk_metrics = compute_jerk_metrics(sample_chunks, decoded)
metrics.update(jerk_metrics)
# Compression
token_lengths = np.array(token_lengths)
input_size = action_horizon * action_dim
compression_ratio = input_size / float(np.mean(token_lengths))
metrics["compression_ratio"] = compression_ratio
metrics["mean_token_length"] = float(np.mean(token_lengths))
metrics["std_token_length"] = float(np.std(token_lengths))
metrics["min_token_length"] = int(np.min(token_lengths))
metrics["max_token_length"] = int(np.max(token_lengths))
metrics["p50_token_length"] = float(np.percentile(token_lengths, 50))
metrics["p99_token_length"] = float(np.percentile(token_lengths, 99))
# Timing (seconds per chunk)
metrics["mean_encode_time_sec"] = float(np.mean(encode_times))
metrics["mean_decode_time_sec"] = float(np.mean(decode_times))
metrics["num_chunks_evaluated"] = sample_size
metrics["total_chunks_available"] = n_chunks
return metrics
def main(
action_tokenizer_path: str,
repo_id: str,
root: str | None = None,
action_horizon: int = 10,
max_episodes: int | None = 100,
sample_fraction: float = 0.2,
encoded_dims: str = "0:6",
delta_dims: str | None = None,
use_delta_transform: bool = False,
state_key: str = OBS_STATE,
normalization_mode: str = "QUANTILES",
max_chunks_for_reconstruction: int | None = 500,
output_dir: str | None = None,
):
if output_dir is None:
output_dir = "outputs/action_tokenizer_benchmark"
output_path = Path(output_dir)
output_path.mkdir(parents=True, exist_ok=True)
try:
norm_mode = NormalizationMode(normalization_mode)
except ValueError:
norm_mode = NormalizationMode.QUANTILES
print("Loading action chunks...")
encoded_chunks, action_dim, horizon, _ = load_action_chunks(
repo_id=repo_id,
root=root,
action_horizon=action_horizon,
max_episodes=max_episodes,
sample_fraction=sample_fraction,
encoded_dims=encoded_dims,
delta_dims=delta_dims,
use_delta_transform=use_delta_transform,
state_key=state_key,
normalization_mode=norm_mode,
)
print(f"Loaded {len(encoded_chunks)} chunks, shape {encoded_chunks.shape} (H={horizon}, D={action_dim})")
print("Running tokenizer benchmark...")
metrics = run_benchmark(
action_chunks=encoded_chunks,
action_horizon=horizon,
action_dim=action_dim,
tokenizer_path=action_tokenizer_path,
max_chunks_for_reconstruction=max_chunks_for_reconstruction,
)
# Attach config for reproducibility
results = {
"config": {
"action_tokenizer_path": action_tokenizer_path,
"repo_id": repo_id,
"action_horizon": action_horizon,
"max_episodes": max_episodes,
"sample_fraction": sample_fraction,
"encoded_dims": encoded_dims,
"delta_dims": delta_dims,
"use_delta_transform": use_delta_transform,
"state_key": state_key,
"normalization_mode": normalization_mode,
},
"metrics": metrics,
}
timestamp = time.strftime("%Y-%m-%d_%H-%M-%S")
safe_repo = repo_id.replace("/", "_")
out_file = output_path / f"{timestamp}_{safe_repo}_action_tokenizer_results.json"
with open(out_file, "w") as f:
json.dump(results, f, indent=2)
print(f"Results saved to {out_file}")
print("Metrics:")
for k, v in metrics.items():
if isinstance(v, list):
print(f" {k}: (length {len(v)})")
else:
print(f" {k}: {v}")
return results
if __name__ == "__main__":
parser = argparse.ArgumentParser(
description="Benchmark action tokenization (reconstruction error, compression, timing)."
)
parser.add_argument(
"--action-tokenizer-path",
type=str,
required=True,
help="Path or HuggingFace repo id of the trained action tokenizer (e.g. outputs/wavetoken).",
)
parser.add_argument(
"--repo-id",
type=str,
required=True,
help="LeRobot dataset repo id (e.g. lerobot/pusht).",
)
parser.add_argument(
"--root",
type=str,
default=None,
help="Root directory for LeRobot datasets.",
)
parser.add_argument(
"--action-horizon",
type=int,
default=10,
help="Number of future steps per action chunk.",
)
parser.add_argument(
"--max-episodes",
type=int,
default=None,
help="Max episodes to use (default: all).",
)
parser.add_argument(
"--sample-fraction",
type=float,
default=0.2,
help="Fraction of chunks to sample per episode.",
)
parser.add_argument(
"--encoded-dims",
type=str,
default="0:6",
help="Dimension ranges to encode (e.g. 0:6,7:14).",
)
parser.add_argument(
"--delta-dims",
type=str,
default=None,
help="Comma-separated dimensions for delta transform.",
)
parser.add_argument(
"--use-delta-transform",
action="store_true",
help="Apply delta (relative) transform to specified dimensions.",
)
parser.add_argument(
"--state-key",
type=str,
default=OBS_STATE,
help="Dataset key for state (for delta transform).",
)
parser.add_argument(
"--normalization-mode",
type=str,
default="QUANTILES",
choices=[m.value for m in NormalizationMode],
help="Normalization mode for actions.",
)
parser.add_argument(
"--max-chunks-for-reconstruction",
type=int,
default=500,
help="Max chunks to use for reconstruction metrics (default: 500).",
)
parser.add_argument(
"--output-dir",
type=str,
default="outputs/action_tokenizer_benchmark",
help="Directory to save results JSON (default: outputs/action_tokenizer_benchmark).",
)
args = parser.parse_args()
main(
action_tokenizer_path=args.action_tokenizer_path,
repo_id=args.repo_id,
root=args.root,
action_horizon=args.action_horizon,
max_episodes=args.max_episodes,
sample_fraction=args.sample_fraction,
encoded_dims=args.encoded_dims,
delta_dims=args.delta_dims,
use_delta_transform=args.use_delta_transform,
state_key=args.state_key,
normalization_mode=args.normalization_mode,
max_chunks_for_reconstruction=args.max_chunks_for_reconstruction,
output_dir=args.output_dir,
)
@@ -166,9 +166,9 @@ def apply_normalization(
if q01 is None or q99 is None:
raise ValueError("QUANTILES mode requires 'q01' and 'q99' in stats")
denom = np.maximum(q99 - q01, eps)
# Clip to quantile range then normalize to [-1, 1]
clipped = np.clip(data, q01, q99)
return 2.0 * (clipped - q01) / denom - 1.0
# No clipping: match training pipeline NormalizerProcessorStep so tokenizer
# is fit on the full range of normalized values (including tails outside [-1, 1]).
return 2.0 * (data - q01) / denom - 1.0
if mode == NormalizationMode.QUANTILE10:
q10 = stats.get("q10")
@@ -176,9 +176,8 @@ def apply_normalization(
if q10 is None or q90 is None:
raise ValueError("QUANTILE10 mode requires 'q10' and 'q90' in stats")
denom = np.maximum(q90 - q10, eps)
# Clip to quantile range then normalize to [-1, 1]
clipped = np.clip(data, q10, q90)
return 2.0 * (clipped - q10) / denom - 1.0
# No clipping: match training pipeline NormalizerProcessorStep.
return 2.0 * (data - q10) / denom - 1.0
raise ValueError(f"Unsupported normalization mode: {mode}")
@@ -306,7 +305,7 @@ def train_fast_tokenizer(
# download the tokenizer source code (not pretrained weights)
# we'll train a new tokenizer on our own data
base_tokenizer = AutoProcessor.from_pretrained("physical-intelligence/fast", trust_remote_code=True)
base_tokenizer = AutoProcessor.from_pretrained("/fsx/jade_choghari/outputs/libero_tokenizer_wavetoken1", trust_remote_code=True)
# convert action_chunks array to list of arrays (expected by .fit())
action_data_list = [action_chunks[i] for i in range(len(action_chunks))]
@@ -320,6 +319,8 @@ def train_fast_tokenizer(
vocab_size=vocab_size,
time_horizon=action_chunks.shape[1], # action_horizon
action_dim=action_chunks.shape[2], # encoded dimensions
wavelet="dmey",
level=1,
)
print("✓ Tokenizer training complete!")