Files
lerobot/src/lerobot/policies/molmoact2/hf_model/action_tokenizer.py
T
Haoquan Fang 24017e960c Add MolmoAct2 policy (#3604)
* add molmoact2 policy

* add apache headers to molmoact2 files

* simplify molmoact2 package imports

* align molmoact2 feature validation with eo pattern

* remove molmoact2 processor override from factory

* guard molmoact2 transformers imports

* guard molmoact2 processor transformers import

* add scipy dependency to molmoact2 extra

* use a single molmoact2 action queue

* move molmoact2 config logic into config

* fix molmoact2 hf image key resolution

* load molmoact2 without remote code

* lazy import molmoact2 scipy

* format molmoact2 files

* skip molmoact2 tests without optional deps

* fix molmoact2 pre-commit checks

* validate molmoact2 gripper range
2026-05-27 18:58:37 +02:00

238 lines
8.5 KiB
Python

#!/usr/bin/env python
# Copyright 2026 The Allen Institute for Artificial Intelligence and 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.
# ruff: noqa
import logging
import os
from pathlib import Path
from typing import ClassVar
import numpy as np
from tokenizers import ByteLevelBPETokenizer
from tokenizers.trainers import BpeTrainer
from huggingface_hub import snapshot_download
from transformers import PreTrainedTokenizerFast
from transformers.processing_utils import ProcessorMixin
def _hf_token() -> str | None:
return os.environ.get("HF_TOKEN") or os.environ.get("HF_ACCESS_TOKEN")
def _resolve_tokenizer_location(
tokenizer_path: str,
*,
revision: str | None = None,
force_download: bool = False,
) -> str:
local_path = Path(str(tokenizer_path)).expanduser()
if local_path.exists():
return str(local_path)
return snapshot_download(
repo_id=str(tokenizer_path),
repo_type="model",
revision=revision,
force_download=force_download,
ignore_patterns=["*.py", "*.pyc", "__pycache__/*"],
token=_hf_token(),
)
class UniversalActionProcessor(ProcessorMixin):
attributes: ClassVar[list[str]] = ["tokenizer"]
tokenizer_class: str = "AutoTokenizer"
def __init__(
self,
tokenizer: PreTrainedTokenizerFast,
scale: float = 10,
vocab_size: int = 1024,
min_token: int = 0,
*,
action_dim: int | None = None,
time_horizon: int | None = None,
):
self.scale = scale
self.vocab_size = vocab_size
self.min_token = min_token
# Action horizon and dimension needed during decoding. These can be specified
# in three ways (in order of priority):
# 1. passed in as kwargs to decode()
# 2. in the constructor
# 3. cached from the last time decode() was called
self.time_horizon = time_horizon
self.action_dim = action_dim
self.called_time_horizon = time_horizon
self.called_action_dim = action_dim
super().__init__(tokenizer)
self.bpe_tokenizer = self.tokenizer
def __call__(self, action_chunk: np.array) -> np.array:
from scipy.fft import dct
assert action_chunk.ndim <= 3, "Only 3 dimensions supported: [batch, timesteps, action_dim]"
if action_chunk.ndim == 2:
action_chunk = action_chunk[None, ...]
# Cache the time horizon and action dimension for decoding
self.called_time_horizon = action_chunk.shape[-2]
self.called_action_dim = action_chunk.shape[-1]
dct_coeff = dct(action_chunk, axis=1, norm="ortho")
dct_coeff = np.around(dct_coeff * self.scale)
tokens = []
for elem in dct_coeff:
token_str = "".join(map(chr, np.maximum(elem.flatten() - self.min_token, 0).astype(int)))
tokens.append(self.bpe_tokenizer(token_str)["input_ids"])
return tokens
def decode(
self,
tokens: list[list[int]],
*,
time_horizon: int | None = None,
action_dim: int | None = None,
) -> np.array:
from scipy.fft import idct
self.time_horizon = time_horizon or self.time_horizon or self.called_time_horizon
self.action_dim = action_dim or self.action_dim or self.called_action_dim
# Cache the time horizon and action dimension for the next call
self.called_time_horizon = self.time_horizon
self.called_action_dim = self.action_dim
assert self.time_horizon is not None and self.action_dim is not None, (
"Tokenizer not initialized, call encode() once or pass in time_horizon and action_dim."
)
decoded_actions = []
for token in tokens:
try:
decoded_tokens = self.bpe_tokenizer.decode(token)
decoded_dct_coeff = np.array(list(map(ord, decoded_tokens))) + self.min_token
decoded_dct_coeff = decoded_dct_coeff.reshape(-1, self.action_dim)
assert decoded_dct_coeff.shape == (
self.time_horizon,
self.action_dim,
), (
f"Decoded DCT coefficients have shape {decoded_dct_coeff.shape}, expected ({self.time_horizon}, {self.action_dim})"
)
except Exception as e:
print(f"Error decoding tokens: {e}")
print(f"Tokens: {token}")
decoded_dct_coeff = np.zeros((self.time_horizon, self.action_dim))
decoded_actions.append(idct(decoded_dct_coeff / self.scale, axis=0, norm="ortho"))
return np.stack(decoded_actions)
@classmethod
def fit(
cls,
action_data: list[np.array],
scale: float = 10,
vocab_size: int = 1024,
*,
time_horizon: int | None = None,
action_dim: int | None = None,
) -> "UniversalActionProcessor":
from scipy.fft import dct
# Run DCT over all inputs
dct_tokens = [dct(a, axis=0, norm="ortho").flatten() for a in action_data]
# Quantize and find min token
max_token = int(np.around(np.concatenate(dct_tokens) * scale).max())
min_token = int(np.around(np.concatenate(dct_tokens) * scale).min())
min_vocab_size = max_token - min_token
assert min_vocab_size <= vocab_size, (
f"Vocab size {vocab_size} is too small for the range of tokens {min_vocab_size}"
)
if min_vocab_size + 100 > vocab_size:
logging.warning(
f"Initial alphabet size {min_vocab_size} is almost as large as the vocab"
f"size {vocab_size}, consider increasing vocab size"
)
# Make token iterator for BPE training
def _token_iter():
for tokens in dct_tokens:
rounded_tokens = np.around(tokens * scale) - min_token
rounded_tokens = rounded_tokens.astype(int)
string = "".join(map(chr, rounded_tokens))
yield string
# Train BPE tokenizer
bpe = ByteLevelBPETokenizer()
# Set up the entire range of possible tokens as the initial alphabet
alphabet = [chr(i) for i in range(max_token - min_token + 1)]
trainer = BpeTrainer(
vocab_size=vocab_size,
min_frequency=2,
show_progress=True,
special_tokens=[],
initial_alphabet=alphabet,
max_token_length=10000,
)
# Train the inner tokenizer (don't use ByteLevelBPETokenizer.train_from_iterator()
# because it doesn't support custom alphabets)
bpe._tokenizer.train_from_iterator(_token_iter(), trainer=trainer)
return cls(
PreTrainedTokenizerFast(tokenizer_object=bpe, clean_up_tokenization_spaces=False),
scale=scale,
vocab_size=vocab_size,
min_token=min_token,
time_horizon=time_horizon,
action_dim=action_dim,
)
@classmethod
def from_pretrained_local(
cls,
pretrained_model_name_or_path: str,
*,
revision: str | None = None,
force_download: bool = False,
) -> "UniversalActionProcessor":
location = Path(
_resolve_tokenizer_location(
pretrained_model_name_or_path,
revision=revision,
force_download=force_download,
)
)
processor_config = {}
processor_config_path = location / "processor_config.json"
if processor_config_path.exists():
import json
processor_config = json.loads(processor_config_path.read_text())
tokenizer = PreTrainedTokenizerFast.from_pretrained(str(location))
return cls(
tokenizer,
scale=processor_config.get("scale", 10),
vocab_size=processor_config.get("vocab_size", 1024),
min_token=processor_config.get("min_token", 0),
action_dim=processor_config.get("action_dim"),
time_horizon=processor_config.get("time_horizon"),
)