Package folder structure (#1417)

* Move files

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* Update doc symlinks

* Update instructions paths

* Fix imports

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src/lerobot/optim/optimizers.py

@@ -0,0 +1,230 @@
+#!/usr/bin/env python
+
+# Copyright 2024 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.
+import abc
+from dataclasses import asdict, dataclass, field
+from pathlib import Path
+from typing import Any
+
+import draccus
+import torch
+from safetensors.torch import load_file, save_file
+
+from lerobot.constants import (
+    OPTIMIZER_PARAM_GROUPS,
+    OPTIMIZER_STATE,
+)
+from lerobot.datasets.utils import flatten_dict, unflatten_dict, write_json
+from lerobot.utils.io_utils import deserialize_json_into_object
+
+
+@dataclass
+class OptimizerConfig(draccus.ChoiceRegistry, abc.ABC):
+    lr: float
+    weight_decay: float
+    grad_clip_norm: float
+
+    @property
+    def type(self) -> str:
+        return self.get_choice_name(self.__class__)
+
+    @classmethod
+    def default_choice_name(cls) -> str | None:
+        return "adam"
+
+    @abc.abstractmethod
+    def build(self) -> torch.optim.Optimizer | dict[str, torch.optim.Optimizer]:
+        """
+        Build the optimizer. It can be a single optimizer or a dictionary of optimizers.
+        NOTE: Multiple optimizers are useful when you have different models to optimize.
+        For example, you can have one optimizer for the policy and another one for the value function
+        in reinforcement learning settings.
+
+        Returns:
+            The optimizer or a dictionary of optimizers.
+        """
+        raise NotImplementedError
+
+
+@OptimizerConfig.register_subclass("adam")
+@dataclass
+class AdamConfig(OptimizerConfig):
+    lr: float = 1e-3
+    betas: tuple[float, float] = (0.9, 0.999)
+    eps: float = 1e-8
+    weight_decay: float = 0.0
+    grad_clip_norm: float = 10.0
+
+    def build(self, params: dict) -> torch.optim.Optimizer:
+        kwargs = asdict(self)
+        kwargs.pop("grad_clip_norm")
+        return torch.optim.Adam(params, **kwargs)
+
+
+@OptimizerConfig.register_subclass("adamw")
+@dataclass
+class AdamWConfig(OptimizerConfig):
+    lr: float = 1e-3
+    betas: tuple[float, float] = (0.9, 0.999)
+    eps: float = 1e-8
+    weight_decay: float = 1e-2
+    grad_clip_norm: float = 10.0
+
+    def build(self, params: dict) -> torch.optim.Optimizer:
+        kwargs = asdict(self)
+        kwargs.pop("grad_clip_norm")
+        return torch.optim.AdamW(params, **kwargs)
+
+
+@OptimizerConfig.register_subclass("sgd")
+@dataclass
+class SGDConfig(OptimizerConfig):
+    lr: float = 1e-3
+    momentum: float = 0.0
+    dampening: float = 0.0
+    nesterov: bool = False
+    weight_decay: float = 0.0
+    grad_clip_norm: float = 10.0
+
+    def build(self, params: dict) -> torch.optim.Optimizer:
+        kwargs = asdict(self)
+        kwargs.pop("grad_clip_norm")
+        return torch.optim.SGD(params, **kwargs)
+
+
+@OptimizerConfig.register_subclass("multi_adam")
+@dataclass
+class MultiAdamConfig(OptimizerConfig):
+    """Configuration for multiple Adam optimizers with different parameter groups.
+
+    This creates a dictionary of Adam optimizers, each with its own hyperparameters.
+
+    Args:
+        lr: Default learning rate (used if not specified for a group)
+        weight_decay: Default weight decay (used if not specified for a group)
+        optimizer_groups: Dictionary mapping parameter group names to their hyperparameters
+        grad_clip_norm: Gradient clipping norm
+    """
+
+    lr: float = 1e-3
+    weight_decay: float = 0.0
+    grad_clip_norm: float = 10.0
+    optimizer_groups: dict[str, dict[str, Any]] = field(default_factory=dict)
+
+    def build(self, params_dict: dict[str, list]) -> dict[str, torch.optim.Optimizer]:
+        """Build multiple Adam optimizers.
+
+        Args:
+            params_dict: Dictionary mapping parameter group names to lists of parameters
+                         The keys should match the keys in optimizer_groups
+
+        Returns:
+            Dictionary mapping parameter group names to their optimizers
+        """
+        optimizers = {}
+
+        for name, params in params_dict.items():
+            # Get group-specific hyperparameters or use defaults
+            group_config = self.optimizer_groups.get(name, {})
+
+            # Create optimizer with merged parameters (defaults + group-specific)
+            optimizer_kwargs = {
+                "lr": group_config.get("lr", self.lr),
+                "betas": group_config.get("betas", (0.9, 0.999)),
+                "eps": group_config.get("eps", 1e-5),
+                "weight_decay": group_config.get("weight_decay", self.weight_decay),
+            }
+
+            optimizers[name] = torch.optim.Adam(params, **optimizer_kwargs)
+
+        return optimizers
+
+
+def save_optimizer_state(
+    optimizer: torch.optim.Optimizer | dict[str, torch.optim.Optimizer], save_dir: Path
+) -> None:
+    """Save optimizer state to disk.
+
+    Args:
+        optimizer: Either a single optimizer or a dictionary of optimizers.
+        save_dir: Directory to save the optimizer state.
+    """
+    if isinstance(optimizer, dict):
+        # Handle dictionary of optimizers
+        for name, opt in optimizer.items():
+            optimizer_dir = save_dir / name
+            optimizer_dir.mkdir(exist_ok=True, parents=True)
+            _save_single_optimizer_state(opt, optimizer_dir)
+    else:
+        # Handle single optimizer
+        _save_single_optimizer_state(optimizer, save_dir)
+
+
+def _save_single_optimizer_state(optimizer: torch.optim.Optimizer, save_dir: Path) -> None:
+    """Save a single optimizer's state to disk."""
+    state = optimizer.state_dict()
+    param_groups = state.pop("param_groups")
+    flat_state = flatten_dict(state)
+    save_file(flat_state, save_dir / OPTIMIZER_STATE)
+    write_json(param_groups, save_dir / OPTIMIZER_PARAM_GROUPS)
+
+
+def load_optimizer_state(
+    optimizer: torch.optim.Optimizer | dict[str, torch.optim.Optimizer], save_dir: Path
+) -> torch.optim.Optimizer | dict[str, torch.optim.Optimizer]:
+    """Load optimizer state from disk.
+
+    Args:
+        optimizer: Either a single optimizer or a dictionary of optimizers.
+        save_dir: Directory to load the optimizer state from.
+
+    Returns:
+        The updated optimizer(s) with loaded state.
+    """
+    if isinstance(optimizer, dict):
+        # Handle dictionary of optimizers
+        loaded_optimizers = {}
+        for name, opt in optimizer.items():
+            optimizer_dir = save_dir / name
+            if optimizer_dir.exists():
+                loaded_optimizers[name] = _load_single_optimizer_state(opt, optimizer_dir)
+            else:
+                loaded_optimizers[name] = opt
+        return loaded_optimizers
+    else:
+        # Handle single optimizer
+        return _load_single_optimizer_state(optimizer, save_dir)
+
+
+def _load_single_optimizer_state(optimizer: torch.optim.Optimizer, save_dir: Path) -> torch.optim.Optimizer:
+    """Load a single optimizer's state from disk."""
+    current_state_dict = optimizer.state_dict()
+    flat_state = load_file(save_dir / OPTIMIZER_STATE)
+    state = unflatten_dict(flat_state)
+
+    # Handle case where 'state' key might not exist (for newly created optimizers)
+    if "state" in state:
+        loaded_state_dict = {"state": {int(k): v for k, v in state["state"].items()}}
+    else:
+        loaded_state_dict = {"state": {}}
+
+    if "param_groups" in current_state_dict:
+        param_groups = deserialize_json_into_object(
+            save_dir / OPTIMIZER_PARAM_GROUPS, current_state_dict["param_groups"]
+        )
+        loaded_state_dict["param_groups"] = param_groups
+
+    optimizer.load_state_dict(loaded_state_dict)
+    return optimizer