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import math
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import warnings
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from collections import deque
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from typing import Callable, List
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import einops
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import numpy as np
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import torch
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import torch.nn.functional as F # noqa: N812
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import torchvision
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from huggingface_hub import PyTorchModelHubMixin
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from torch import Tensor, nn
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from torch.optim.lr_scheduler import LambdaLR
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from lerobot.common.policies.normalize import Normalize, Unnormalize
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from lerobot.common.policies.utils import get_device_from_parameters, populate_queues
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from lerobot.common.policies.vqbet.configuration_vqbet import VQBeTConfig
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from lerobot.common.policies.vqbet.vqbet_utils import GPT, ResidualVQ
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# ruff: noqa: N806
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class VQBeTPolicy(nn.Module, PyTorchModelHubMixin):
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"""
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VQ-BeT Policy as per "Behavior Generation with Latent Actions"
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"""
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name = "vqbet"
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def __init__(
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self,
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config: VQBeTConfig | None = None,
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dataset_stats: dict[str, dict[str, Tensor]] | None = None,
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):
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"""
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Args:
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config: Policy configuration class instance or None, in which case the default instantiation of
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the configuration class is used.
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dataset_stats: Dataset statistics to be used for normalization. If not passed here, it is expected
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that they will be passed with a call to `load_state_dict` before the policy is used.
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"""
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super().__init__()
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if config is None:
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config = VQBeTConfig()
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self.config = config
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self.normalize_inputs = Normalize(
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config.input_shapes, config.input_normalization_modes, dataset_stats
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)
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self.normalize_targets = Normalize(
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config.output_shapes, config.output_normalization_modes, dataset_stats
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)
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self.unnormalize_outputs = Unnormalize(
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config.output_shapes, config.output_normalization_modes, dataset_stats
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)
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self.vqbet = VQBeTModel(config)
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self.expected_image_keys = [k for k in config.input_shapes if k.startswith("observation.image")]
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self.reset()
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def reset(self):
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"""
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Clear observation and action queues. Should be called on `env.reset()`
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queues are populated during rollout of the policy, they contain the n latest observations and actions
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"""
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self._queues = {
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"observation.images": deque(maxlen=self.config.n_obs_steps),
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"observation.state": deque(maxlen=self.config.n_obs_steps),
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"action": deque(maxlen=self.config.action_chunk_size),
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}
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@torch.no_grad
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def select_action(self, batch: dict[str, Tensor]) -> Tensor:
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"""Select a single action given environment observations.
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This method wraps `select_actions` in order to return one action at a time for execution in the
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environment. It works by managing the actions in a queue and only calling `select_actions` when the
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queue is empty.
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"""
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batch = self.normalize_inputs(batch)
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batch["observation.images"] = torch.stack([batch[k] for k in self.expected_image_keys], dim=-4)
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# Note: It's important that this happens after stacking the images into a single key.
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self._queues = populate_queues(self._queues, batch)
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if not self.vqbet.action_head.vqvae_model.discretized.item():
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warnings.warn(
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"To evaluate in the environment, your VQ-BeT model should contain a pretrained Residual VQ.",
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stacklevel=1,
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)
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if len(self._queues["action"]) == 0:
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batch = {k: torch.stack(list(self._queues[k]), dim=1) for k in batch if k in self._queues}
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actions = self.vqbet(batch, rollout=True)[:, : self.config.action_chunk_size]
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# the dimension of returned action is (batch_size, action_chunk_size, action_dim)
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actions = self.unnormalize_outputs({"action": actions})["action"]
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# since the data in the action queue's dimension is (action_chunk_size, batch_size, action_dim), we transpose the action and fill the queue
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self._queues["action"].extend(actions.transpose(0, 1))
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action = self._queues["action"].popleft()
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return action
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def forward(self, batch: dict[str, Tensor]) -> dict[str, Tensor]:
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"""Run the batch through the model and compute the loss for training or validation."""
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batch = self.normalize_inputs(batch)
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batch["observation.images"] = torch.stack([batch[k] for k in self.expected_image_keys], dim=-4)
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batch = self.normalize_targets(batch)
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# VQ-BeT discretizes action using VQ-VAE before training BeT (please refer to section 3.2 in the VQ-BeT paper https://arxiv.org/pdf/2403.03181)
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if not self.vqbet.action_head.vqvae_model.discretized.item():
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# loss: total loss of training RVQ
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# n_different_codes: how many of the total possible VQ codes are being used in single batch (how many of them have at least one encoder embedding as a nearest neighbor). This can be at most `vqvae_n_embed * number of layers of RVQ (=2)`.
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# n_different_combinations: how many different code combinations are being used out of all possible combinations in single batch. This can be at most `vqvae_n_embed ^ number of layers of RVQ (=2)` (hint consider the RVQ as a decision tree).
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loss, n_different_codes, n_different_combinations, recon_l1_error = (
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self.vqbet.action_head.discretize(self.config.n_vqvae_training_steps, batch["action"])
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)
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return {
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"loss": loss,
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"n_different_codes": n_different_codes,
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"n_different_combinations": n_different_combinations,
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"recon_l1_error": recon_l1_error,
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}
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# if Residual VQ is already trained, VQ-BeT trains its GPT and bin prediction head / offset prediction head parts.
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_, loss_dict = self.vqbet(batch, rollout=False)
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return loss_dict
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class SpatialSoftmax(nn.Module):
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"""
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Spatial Soft Argmax operation described in "Deep Spatial Autoencoders for Visuomotor Learning" by Finn et al.
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(https://arxiv.org/pdf/1509.06113). A minimal port of the robomimic implementation.
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At a high level, this takes 2D feature maps (from a convnet/ViT) and returns the "center of mass"
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of activations of each channel, i.e., keypoints in the image space for the policy to focus on.
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Example: take feature maps of size (512x10x12). We generate a grid of normalized coordinates (10x12x2):
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-----------------------------------------------------
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| (-1., -1.) | (-0.82, -1.) | ... | (1., -1.) |
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| (-1., -0.78) | (-0.82, -0.78) | ... | (1., -0.78) |
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| ... | ... | ... | ... |
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| (-1., 1.) | (-0.82, 1.) | ... | (1., 1.) |
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-----------------------------------------------------
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This is achieved by applying channel-wise softmax over the activations (512x120) and computing the dot
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product with the coordinates (120x2) to get expected points of maximal activation (512x2).
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The example above results in 512 keypoints (corresponding to the 512 input channels). We can optionally
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provide num_kp != None to control the number of keypoints. This is achieved by a first applying a learnable
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linear mapping (in_channels, H, W) -> (num_kp, H, W).
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"""
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def __init__(self, input_shape, num_kp=None):
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"""
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Args:
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input_shape (list): (C, H, W) input feature map shape.
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num_kp (int): number of keypoints in output. If None, output will have the same number of channels as input.
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"""
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super().__init__()
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assert len(input_shape) == 3
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self._in_c, self._in_h, self._in_w = input_shape
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if num_kp is not None:
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self.nets = torch.nn.Conv2d(self._in_c, num_kp, kernel_size=1)
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self._out_c = num_kp
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else:
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self.nets = None
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self._out_c = self._in_c
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# we could use torch.linspace directly but that seems to behave slightly differently than numpy
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# and causes a small degradation in pc_success of pre-trained models.
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pos_x, pos_y = np.meshgrid(np.linspace(-1.0, 1.0, self._in_w), np.linspace(-1.0, 1.0, self._in_h))
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pos_x = torch.from_numpy(pos_x.reshape(self._in_h * self._in_w, 1)).float()
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pos_y = torch.from_numpy(pos_y.reshape(self._in_h * self._in_w, 1)).float()
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# register as buffer so it's moved to the correct device.
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self.register_buffer("pos_grid", torch.cat([pos_x, pos_y], dim=1))
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def forward(self, features: Tensor) -> Tensor:
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"""
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Args:
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features: (B, C, H, W) input feature maps.
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Returns:
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(B, K, 2) image-space coordinates of keypoints.
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"""
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if self.nets is not None:
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features = self.nets(features)
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# [B, K, H, W] -> [B * K, H * W] where K is number of keypoints
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features = features.reshape(-1, self._in_h * self._in_w)
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# 2d softmax normalization
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attention = F.softmax(features, dim=-1)
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# [B * K, H * W] x [H * W, 2] -> [B * K, 2] for spatial coordinate mean in x and y dimensions
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expected_xy = attention @ self.pos_grid
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# reshape to [B, K, 2]
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feature_keypoints = expected_xy.view(-1, self._out_c, 2)
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return feature_keypoints
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class VQBeTModel(nn.Module):
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"""VQ-BeT: The underlying neural network for VQ-BeT
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Note: In this code we use the terms `rgb_encoder`, 'policy', `action_head`. The meanings are as follows.
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- The `rgb_encoder` process rgb-style image observations to one-dimensional embedding vectors
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- A `policy` is a minGPT architecture, that takes observation sequences and action query tokens to generate `features`.
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- These `features` pass through the action head, which passes through the code prediction, offset prediction head,
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and finally generates a prediction for the action chunks.
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-------------------------------** legend **-------------------------------
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│ n = n_obs_steps, p = n_action_pred_token, c = action_chunk_size) │
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│ o_{t} : visual observation at timestep {t} │
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│ s_{t} : state observation at timestep {t} │
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│ a_{t} : action at timestep {t} │
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│ A_Q : action_query_token │
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--------------------------------------------------------------------------
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Training Phase 1. Discretize action using Residual VQ (for config.n_vqvae_training_steps steps)
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┌─────────────────┐ ┌─────────────────┐ ┌─────────────────┐
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│ │ │ │ │ │
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│ RVQ encoder │ ─► │ Residual │ ─► │ RVQ Decoder │
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│ (a_{t}~a_{t+p}) │ │ Code Quantizer │ │ │
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│ │ │ │ │ │
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└─────────────────┘ └─────────────────┘ └─────────────────┘
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Training Phase 2.
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timestep {t-n+1} timestep {t-n+2} timestep {t}
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┌─────┴─────┐ ┌─────┴─────┐ ┌─────┴─────┐
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o_{t-n+1} o_{t-n+2} ... o_{t}
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│ │ │
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│ s_{t-n+1} │ s_{t-n+2} ... │ s_{t} p
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│ │ │ │ │ │ ┌───────┴───────┐
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│ │ A_Q │ │ A_Q ... │ │ A_Q ... A_Q
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│ │ │ │ │ │ │ │ │ │
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┌───▼─────▼─────▼─────▼─────▼─────▼─────────────────▼─────▼─────▼───────────────▼───┐
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│ │
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│ GPT │ => policy
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│ │
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└───────────────▼─────────────────▼─────────────────────────────▼───────────────▼───┘
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│ │ │ │
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┌───┴───┐ ┌───┴───┐ ┌───┴───┐ ┌───┴───┐
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code offset code offset code offset code offset
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▼ │ ▼ │ ▼ │ ▼ │ => action_head
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RVQ Decoder │ RVQ Decoder │ RVQ Decoder │ RVQ Decoder │
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└── + ──┘ └── + ──┘ └── + ──┘ └── + ──┘
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▼ ▼ ▼ ▼
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action chunk action chunk action chunk action chunk
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a_{t-n+1} ~ a_{t-n+2} ~ a_{t} ~ ... a_{t+p-1} ~
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a_{t-n+c} a_{t-n+c+1} a_{t+c-1} a_{t+p+c-1}
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▼
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ONLY this chunk is used in rollout!
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"""
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def __init__(self, config: VQBeTConfig):
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super().__init__()
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self.config = config
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self.rgb_encoder = VQBeTRgbEncoder(config)
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self.num_images = len([k for k in config.input_shapes if k.startswith("observation.image")])
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# This action query token is used as a prompt for querying action chunks. Please refer to "A_Q" in the image above.
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# Note: During the forward pass, this token is repeated as many times as needed. The authors also experimented with initializing the necessary number of tokens independently and observed inferior results.
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self.action_token = nn.Parameter(torch.randn(1, 1, self.config.gpt_input_dim))
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# To input state and observation features into GPT layers, we first project the features to fit the shape of input size of GPT.
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self.state_projector = MLP(
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config.output_shapes["action"][0], hidden_channels=[self.config.gpt_input_dim]
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)
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self.rgb_feature_projector = MLP(
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self.rgb_encoder.feature_dim, hidden_channels=[self.config.gpt_input_dim]
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)
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# GPT part of VQ-BeT
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self.policy = GPT(config)
|
|
|
|
|
# bin prediction head / offset prediction head part of VQ-BeT
|
|
|
|
|
self.action_head = VQBeTHead(config)
|
|
|
|
|
|
|
|
|
|
num_tokens = self.config.n_action_pred_token + self.config.action_chunk_size - 1
|
|
|
|
|
self.register_buffer(
|
|
|
|
|
"select_target_actions_indices",
|
|
|
|
|
torch.row_stack([torch.arange(i, i + self.config.action_chunk_size) for i in range(num_tokens)]),
|
|
|
|
|
)
|
|
|
|
|
|
|
|
|
|
def forward(self, batch: dict[str, Tensor], rollout: bool) -> Tensor:
|
|
|
|
|
# Input validation.
|
|
|
|
|
assert set(batch).issuperset({"observation.state", "observation.images"})
|
|
|
|
|
batch_size, n_obs_steps = batch["observation.state"].shape[:2]
|
|
|
|
|
assert n_obs_steps == self.config.n_obs_steps
|
|
|
|
|
|
|
|
|
|
# Extract image feature (first combine batch and sequence dims).
|
|
|
|
|
img_features = self.rgb_encoder(
|
|
|
|
|
einops.rearrange(batch["observation.images"], "b s n ... -> (b s n) ...")
|
|
|
|
|
)
|
|
|
|
|
# Separate batch and sequence dims.
|
|
|
|
|
img_features = einops.rearrange(
|
|
|
|
|
img_features, "(b s n) ... -> b s n ...", b=batch_size, s=n_obs_steps, n=self.num_images
|
|
|
|
|
)
|
|
|
|
|
|
|
|
|
|
# Arrange prior and current observation step tokens as shown in the class docstring.
|
|
|
|
|
# First project features to token dimension.
|
|
|
|
|
rgb_tokens = self.rgb_feature_projector(
|
|
|
|
|
img_features
|
|
|
|
|
) # (batch, obs_step, number of different cameras, projection dims)
|
|
|
|
|
input_tokens = [rgb_tokens[:, :, i] for i in range(rgb_tokens.size(2))]
|
|
|
|
|
input_tokens.append(
|
|
|
|
|
self.state_projector(batch["observation.state"])
|
|
|
|
|
) # (batch, obs_step, projection dims)
|
|
|
|
|
input_tokens.append(einops.repeat(self.action_token, "1 1 d -> b n d", b=batch_size, n=n_obs_steps))
|
|
|
|
|
# Interleave tokens by stacking and rearranging.
|
|
|
|
|
input_tokens = torch.stack(input_tokens, dim=2)
|
|
|
|
|
input_tokens = einops.rearrange(input_tokens, "b n t d -> b (n t) d")
|
|
|
|
|
|
|
|
|
|
len_additional_action_token = self.config.n_action_pred_token - 1
|
|
|
|
|
future_action_tokens = self.action_token.repeat(batch_size, len_additional_action_token, 1)
|
|
|
|
|
|
|
|
|
|
# add additional action query tokens for predicting future action chunks
|
|
|
|
|
input_tokens = torch.cat([input_tokens, future_action_tokens], dim=1)
|
|
|
|
|
|
|
|
|
|
# get action features (pass through GPT)
|
|
|
|
|
features = self.policy(input_tokens)
|
|
|
|
|
# len(self.config.input_shapes) is the number of different observation modes. this line gets the index of action prompt tokens.
|
|
|
|
|
historical_act_pred_index = np.arange(0, n_obs_steps) * (len(self.config.input_shapes) + 1) + len(
|
|
|
|
|
self.config.input_shapes
|
|
|
|
|
)
|
|
|
|
|
|
|
|
|
|
# only extract the output tokens at the position of action query:
|
|
|
|
|
# Behavior Transformer (BeT), and VQ-BeT are both sequence-to-sequence prediction models, mapping sequential observation to sequential action (please refer to section 2.2 in BeT paper https://arxiv.org/pdf/2206.11251).
|
|
|
|
|
# Thus, it predict historical action sequence, in addition to current and future actions (predicting future actions : optional).
|
|
|
|
|
features = torch.cat(
|
|
|
|
|
[features[:, historical_act_pred_index], features[:, -len_additional_action_token:]], dim=1
|
|
|
|
|
)
|
|
|
|
|
# pass through action head
|
|
|
|
|
action_head_output = self.action_head(features)
|
|
|
|
|
# if rollout, VQ-BeT don't calculate loss
|
|
|
|
|
if rollout:
|
|
|
|
|
return action_head_output["predicted_action"][:, n_obs_steps - 1, :].reshape(
|
|
|
|
|
batch_size, self.config.action_chunk_size, -1
|
|
|
|
|
)
|
|
|
|
|
# else, it calculate overall loss (bin prediction loss, and offset loss)
|
|
|
|
|
else:
|
|
|
|
|
output = batch["action"][:, self.select_target_actions_indices]
|
|
|
|
|
loss = self.action_head.loss_fn(action_head_output, output, reduction="mean")
|
|
|
|
|
return action_head_output, loss
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
class VQBeTHead(nn.Module):
|
|
|
|
|
def __init__(self, config: VQBeTConfig):
|
|
|
|
|
"""
|
|
|
|
|
VQBeTHead takes output of GPT layers, and pass the feature through bin prediction head (`self.map_to_cbet_preds_bin`), and offset prediction head (`self.map_to_cbet_preds_offset`)
|
|
|
|
|
|
|
|
|
|
self.map_to_cbet_preds_bin: outputs probability of each code (for each layer).
|
|
|
|
|
The input dimension of `self.map_to_cbet_preds_bin` is same with the output of GPT,
|
|
|
|
|
and the output dimension of `self.map_to_cbet_preds_bin` is `self.vqvae_model.vqvae_num_layers (=fixed as 2) * self.config.vqvae_n_embed`.
|
|
|
|
|
if the agent select the code sequentially, we use self.map_to_cbet_preds_primary_bin and self.map_to_cbet_preds_secondary_bin instead of self._map_to_cbet_preds_bin.
|
|
|
|
|
|
|
|
|
|
self.map_to_cbet_preds_offset: output the predicted offsets for all the codes in all the layers.
|
|
|
|
|
The input dimension of ` self.map_to_cbet_preds_offset` is same with the output of GPT,
|
|
|
|
|
and the output dimension of ` self.map_to_cbet_preds_offset` is `self.vqvae_model.vqvae_num_layers (=fixed as 2) * self.config.vqvae_n_embed * config.action_chunk_size * config.output_shapes["action"][0]`.
|
|
|
|
|
"""
|
|
|
|
|
|
|
|
|
|
super().__init__()
|
|
|
|
|
self.config = config
|
|
|
|
|
# init vqvae
|
|
|
|
|
self.vqvae_model = VqVae(config)
|
|
|
|
|
if config.sequentially_select:
|
|
|
|
|
self.map_to_cbet_preds_primary_bin = MLP(
|
|
|
|
|
in_channels=config.gpt_output_dim,
|
|
|
|
|
hidden_channels=[self.config.vqvae_n_embed],
|
|
|
|
|
)
|
|
|
|
|
self.map_to_cbet_preds_secondary_bin = MLP(
|
|
|
|
|
in_channels=config.gpt_output_dim + self.config.vqvae_n_embed,
|
|
|
|
|
hidden_channels=[self.config.vqvae_n_embed],
|
|
|
|
|
)
|
|
|
|
|
else:
|
|
|
|
|
self.map_to_cbet_preds_bin = MLP(
|
|
|
|
|
in_channels=config.gpt_output_dim,
|
|
|
|
|
hidden_channels=[self.vqvae_model.vqvae_num_layers * self.config.vqvae_n_embed],
|
|
|
|
|
)
|
|
|
|
|
self.map_to_cbet_preds_offset = MLP(
|
|
|
|
|
in_channels=config.gpt_output_dim,
|
|
|
|
|
hidden_channels=[
|
|
|
|
|
self.vqvae_model.vqvae_num_layers
|
|
|
|
|
* self.config.vqvae_n_embed
|
|
|
|
|
* config.action_chunk_size
|
|
|
|
|
* config.output_shapes["action"][0],
|
|
|
|
|
],
|
|
|
|
|
)
|
|
|
|
|
# loss
|
|
|
|
|
self._focal_loss_fn = FocalLoss(gamma=2.0)
|
|
|
|
|
|
|
|
|
|
def discretize(self, n_vqvae_training_steps, actions):
|
|
|
|
|
# Resize the action sequence data to fit the action chunk size using a sliding window approach.
|
|
|
|
|
actions = torch.cat(
|
|
|
|
|
[
|
|
|
|
|
actions[:, j : j + self.config.action_chunk_size, :]
|
|
|
|
|
for j in range(actions.shape[1] + 1 - self.config.action_chunk_size)
|
|
|
|
|
],
|
|
|
|
|
dim=0,
|
|
|
|
|
)
|
|
|
|
|
# `actions` is a tensor of shape (new_batch, action_chunk_size, action_dim) where new_batch is the number of possible chunks created from the original sequences using the sliding window.
|
|
|
|
|
|
|
|
|
|
loss, metric = self.vqvae_model.vqvae_forward(actions)
|
|
|
|
|
n_different_codes = sum(
|
|
|
|
|
[len(torch.unique(metric[2][:, i])) for i in range(self.vqvae_model.vqvae_num_layers)]
|
|
|
|
|
)
|
|
|
|
|
n_different_combinations = len(torch.unique(metric[2], dim=0))
|
|
|
|
|
recon_l1_error = metric[0].detach().cpu().item()
|
|
|
|
|
self.vqvae_model.optimized_steps += 1
|
|
|
|
|
# if we updated RVQ more than `n_vqvae_training_steps` steps, we freeze the RVQ part.
|
|
|
|
|
if self.vqvae_model.optimized_steps >= n_vqvae_training_steps:
|
|
|
|
|
self.vqvae_model.discretized = torch.tensor(True)
|
|
|
|
|
self.vqvae_model.vq_layer.freeze_codebook = torch.tensor(True)
|
|
|
|
|
print("Finished discretizing action data!")
|
|
|
|
|
self.vqvae_model.eval()
|
|
|
|
|
for param in self.vqvae_model.vq_layer.parameters():
|
|
|
|
|
param.requires_grad = False
|
|
|
|
|
return loss, n_different_codes, n_different_combinations, recon_l1_error
|
|
|
|
|
|
|
|
|
|
def forward(self, x, **kwargs):
|
|
|
|
|
# N is the batch size, and T is number of action query tokens, which are process through same GPT
|
|
|
|
|
N, T, _ = x.shape
|
|
|
|
|
# we calculate N and T side parallely. Thus, the dimensions would be
|
|
|
|
|
# (batch size * number of action query tokens, action chunk size, action dimension)
|
|
|
|
|
x = einops.rearrange(x, "N T WA -> (N T) WA")
|
|
|
|
|
|
|
|
|
|
# sample offsets
|
|
|
|
|
cbet_offsets = self.map_to_cbet_preds_offset(x)
|
|
|
|
|
cbet_offsets = einops.rearrange(
|
|
|
|
|
cbet_offsets,
|
|
|
|
|
"(NT) (G C WA) -> (NT) G C WA",
|
|
|
|
|
G=self.vqvae_model.vqvae_num_layers,
|
|
|
|
|
C=self.config.vqvae_n_embed,
|
|
|
|
|
)
|
|
|
|
|
# if self.config.sequentially_select is True, bin prediction head first sample the primary code, and then sample secondary code
|
|
|
|
|
if self.config.sequentially_select:
|
|
|
|
|
cbet_primary_logits = self.map_to_cbet_preds_primary_bin(x)
|
|
|
|
|
|
|
|
|
|
# select primary bin first
|
|
|
|
|
cbet_primary_probs = torch.softmax(
|
|
|
|
|
cbet_primary_logits / self.config.bet_softmax_temperature, dim=-1
|
|
|
|
|
)
|
|
|
|
|
NT, choices = cbet_primary_probs.shape
|
|
|
|
|
sampled_primary_centers = einops.rearrange(
|
|
|
|
|
torch.multinomial(cbet_primary_probs.view(-1, choices), num_samples=1),
|
|
|
|
|
"(NT) 1 -> NT",
|
|
|
|
|
NT=NT,
|
|
|
|
|
)
|
|
|
|
|
|
|
|
|
|
cbet_secondary_logits = self.map_to_cbet_preds_secondary_bin(
|
|
|
|
|
torch.cat(
|
|
|
|
|
(x, F.one_hot(sampled_primary_centers, num_classes=self.config.vqvae_n_embed)),
|
|
|
|
|
axis=1,
|
|
|
|
|
)
|
|
|
|
|
)
|
|
|
|
|
cbet_secondary_probs = torch.softmax(
|
|
|
|
|
cbet_secondary_logits / self.config.bet_softmax_temperature, dim=-1
|
|
|
|
|
)
|
|
|
|
|
sampled_secondary_centers = einops.rearrange(
|
|
|
|
|
torch.multinomial(cbet_secondary_probs.view(-1, choices), num_samples=1),
|
|
|
|
|
"(NT) 1 -> NT",
|
|
|
|
|
NT=NT,
|
|
|
|
|
)
|
|
|
|
|
sampled_centers = torch.stack((sampled_primary_centers, sampled_secondary_centers), axis=1)
|
|
|
|
|
cbet_logits = torch.stack([cbet_primary_logits, cbet_secondary_logits], dim=1)
|
|
|
|
|
# if self.config.sequentially_select is False, bin prediction head samples primary and secondary code at once.
|
|
|
|
|
else:
|
|
|
|
|
cbet_logits = self.map_to_cbet_preds_bin(x)
|
|
|
|
|
cbet_logits = einops.rearrange(
|
|
|
|
|
cbet_logits, "(NT) (G C) -> (NT) G C", G=self.vqvae_model.vqvae_num_layers
|
|
|
|
|
)
|
|
|
|
|
cbet_probs = torch.softmax(cbet_logits / self.config.bet_softmax_temperature, dim=-1)
|
|
|
|
|
NT, G, choices = cbet_probs.shape
|
|
|
|
|
sampled_centers = einops.rearrange(
|
|
|
|
|
torch.multinomial(cbet_probs.view(-1, choices), num_samples=1),
|
|
|
|
|
"(NT G) 1 -> NT G",
|
|
|
|
|
NT=NT,
|
|
|
|
|
)
|
|
|
|
|
|
|
|
|
|
device = get_device_from_parameters(self)
|
|
|
|
|
indices = (
|
|
|
|
|
torch.arange(NT, device=device).unsqueeze(1),
|
|
|
|
|
torch.arange(self.vqvae_model.vqvae_num_layers, device=device).unsqueeze(0),
|
|
|
|
|
sampled_centers,
|
|
|
|
|
)
|
|
|
|
|
# Use advanced indexing to sample the values (Extract the only offsets corresponding to the sampled codes.)
|
|
|
|
|
sampled_offsets = cbet_offsets[indices]
|
|
|
|
|
# Then, sum the offsets over the RVQ layers to get a net offset for the bin prediction
|
|
|
|
|
sampled_offsets = sampled_offsets.sum(dim=1)
|
|
|
|
|
with torch.no_grad():
|
|
|
|
|
# Get the centroids (= vectors corresponding to the codes) of each layer to pass it through RVQ decoder
|
|
|
|
|
return_decoder_input = self.vqvae_model.get_embeddings_from_code(sampled_centers).clone().detach()
|
|
|
|
|
# pass the centroids through decoder to get actions.
|
|
|
|
|
decoded_action = self.vqvae_model.get_action_from_latent(return_decoder_input).clone().detach()
|
|
|
|
|
# reshaped extracted offset to match with decoded centroids
|
|
|
|
|
sampled_offsets = einops.rearrange(
|
|
|
|
|
sampled_offsets, "NT (W A) -> NT W A", W=self.config.action_chunk_size
|
|
|
|
|
)
|
|
|
|
|
# add offset and decoded centroids
|
|
|
|
|
predicted_action = decoded_action + sampled_offsets
|
|
|
|
|
predicted_action = einops.rearrange(
|
|
|
|
|
predicted_action,
|
|
|
|
|
"(N T) W A -> N T (W A)",
|
|
|
|
|
N=N,
|
|
|
|
|
T=T,
|
|
|
|
|
W=self.config.action_chunk_size,
|
|
|
|
|
)
|
|
|
|
|
|
|
|
|
|
return {
|
|
|
|
|
"cbet_logits": cbet_logits,
|
|
|
|
|
"predicted_action": predicted_action,
|
|
|
|
|
"sampled_centers": sampled_centers,
|
|
|
|
|
"decoded_action": decoded_action,
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
def loss_fn(self, pred, target, **kwargs):
|
|
|
|
|
"""
|
|
|
|
|
for given ground truth action values (target), and prediction (pred) this function calculates the overall loss.
|
|
|
|
|
|
|
|
|
|
predicted_action: predicted action chunk (offset + decoded centroids)
|
|
|
|
|
sampled_centers: sampled centroids (code of RVQ)
|
|
|
|
|
decoded_action: decoded action, which is produced by passing sampled_centers through RVQ decoder
|
|
|
|
|
NT: batch size * T
|
|
|
|
|
T: number of action query tokens, which are process through same GPT
|
|
|
|
|
cbet_logits: probability of all codes in each layer
|
|
|
|
|
"""
|
|
|
|
|
action_seq = target
|
|
|
|
|
predicted_action = pred["predicted_action"]
|
|
|
|
|
sampled_centers = pred["sampled_centers"]
|
|
|
|
|
decoded_action = pred["decoded_action"]
|
|
|
|
|
NT = predicted_action.shape[0] * predicted_action.shape[1]
|
|
|
|
|
|
|
|
|
|
cbet_logits = pred["cbet_logits"]
|
|
|
|
|
|
|
|
|
|
predicted_action = einops.rearrange(
|
|
|
|
|
predicted_action, "N T (W A) -> (N T) W A", W=self.config.action_chunk_size
|
|
|
|
|
)
|
|
|
|
|
|
|
|
|
|
action_seq = einops.rearrange(action_seq, "N T W A -> (N T) W A")
|
|
|
|
|
# Figure out the loss for the actions.
|
|
|
|
|
# First, we need to find the closest cluster center for each ground truth action.
|
|
|
|
|
with torch.no_grad():
|
|
|
|
|
state_vq, action_bins = self.vqvae_model.get_code(action_seq) # action_bins: NT, G
|
|
|
|
|
|
|
|
|
|
# Now we can compute the loss.
|
|
|
|
|
|
|
|
|
|
# offset loss is L1 distance between the predicted action and ground truth action
|
|
|
|
|
offset_loss = F.l1_loss(action_seq, predicted_action)
|
|
|
|
|
|
|
|
|
|
# calculate primary code prediction loss
|
|
|
|
|
cbet_loss1 = self._focal_loss_fn(
|
|
|
|
|
cbet_logits[:, 0, :],
|
|
|
|
|
action_bins[:, 0],
|
|
|
|
|
)
|
|
|
|
|
# calculate secondary code prediction loss
|
|
|
|
|
cbet_loss2 = self._focal_loss_fn(
|
|
|
|
|
cbet_logits[:, 1, :],
|
|
|
|
|
action_bins[:, 1],
|
|
|
|
|
)
|
|
|
|
|
# add all the prediction loss
|
|
|
|
|
cbet_loss = (
|
|
|
|
|
cbet_loss1 * self.config.primary_code_loss_weight
|
|
|
|
|
+ cbet_loss2 * self.config.secondary_code_loss_weight
|
|
|
|
|
)
|
|
|
|
|
|
|
|
|
|
equal_primary_code_rate = torch.sum((action_bins[:, 0] == sampled_centers[:, 0]).int()) / (NT)
|
|
|
|
|
equal_secondary_code_rate = torch.sum((action_bins[:, 1] == sampled_centers[:, 1]).int()) / (NT)
|
|
|
|
|
|
|
|
|
|
action_mse_error = torch.mean((action_seq - predicted_action) ** 2)
|
|
|
|
|
vq_action_error = torch.mean(torch.abs(action_seq - decoded_action))
|
|
|
|
|
offset_action_error = torch.mean(torch.abs(action_seq - predicted_action))
|
|
|
|
|
action_error_max = torch.max(torch.abs(action_seq - predicted_action))
|
|
|
|
|
|
|
|
|
|
loss = cbet_loss + self.config.offset_loss_weight * offset_loss
|
|
|
|
|
|
|
|
|
|
loss_dict = {
|
|
|
|
|
"loss": loss,
|
|
|
|
|
"classification_loss": cbet_loss.detach().cpu().item(),
|
|
|
|
|
"offset_loss": offset_loss.detach().cpu().item(),
|
|
|
|
|
"equal_primary_code_rate": equal_primary_code_rate.detach().cpu().item(),
|
|
|
|
|
"equal_secondary_code_rate": equal_secondary_code_rate.detach().cpu().item(),
|
|
|
|
|
"vq_action_error": vq_action_error.detach().cpu().item(),
|
|
|
|
|
"offset_action_error": offset_action_error.detach().cpu().item(),
|
|
|
|
|
"action_error_max": action_error_max.detach().cpu().item(),
|
|
|
|
|
"action_mse_error": action_mse_error.detach().cpu().item(),
|
|
|
|
|
}
|
|
|
|
|
return loss_dict
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
class VQBeTOptimizer(torch.optim.Adam):
|
|
|
|
|
def __init__(self, policy, cfg):
|
|
|
|
|
vqvae_params = (
|
|
|
|
|
list(policy.vqbet.action_head.vqvae_model.encoder.parameters())
|
|
|
|
|
+ list(policy.vqbet.action_head.vqvae_model.decoder.parameters())
|
|
|
|
|
+ list(policy.vqbet.action_head.vqvae_model.vq_layer.parameters())
|
|
|
|
|
)
|
|
|
|
|
decay_params, no_decay_params = policy.vqbet.policy.configure_parameters()
|
|
|
|
|
decay_params = (
|
|
|
|
|
decay_params
|
|
|
|
|
+ list(policy.vqbet.rgb_encoder.parameters())
|
|
|
|
|
+ list(policy.vqbet.state_projector.parameters())
|
|
|
|
|
+ list(policy.vqbet.rgb_feature_projector.parameters())
|
|
|
|
|
+ [policy.vqbet.action_token]
|
|
|
|
|
+ list(policy.vqbet.action_head.map_to_cbet_preds_offset.parameters())
|
|
|
|
|
)
|
|
|
|
|
|
|
|
|
|
if cfg.policy.sequentially_select:
|
|
|
|
|
decay_params = (
|
|
|
|
|
decay_params
|
|
|
|
|
+ list(policy.vqbet.action_head.map_to_cbet_preds_primary_bin.parameters())
|
|
|
|
|
+ list(policy.vqbet.action_head.map_to_cbet_preds_secondary_bin.parameters())
|
|
|
|
|
)
|
|
|
|
|
else:
|
|
|
|
|
decay_params = decay_params + list(policy.vqbet.action_head.map_to_cbet_preds_bin.parameters())
|
|
|
|
|
|
|
|
|
|
optim_groups = [
|
|
|
|
|
{
|
|
|
|
|
"params": decay_params,
|
|
|
|
|
"weight_decay": cfg.training.adam_weight_decay,
|
|
|
|
|
"lr": cfg.training.lr,
|
|
|
|
|
},
|
|
|
|
|
{
|
|
|
|
|
"params": vqvae_params,
|
|
|
|
|
"weight_decay": 0.0001,
|
|
|
|
|
"lr": cfg.training.vqvae_lr,
|
|
|
|
|
},
|
|
|
|
|
{
|
|
|
|
|
"params": no_decay_params,
|
|
|
|
|
"weight_decay": 0.0,
|
|
|
|
|
"lr": cfg.training.lr,
|
|
|
|
|
},
|
|
|
|
|
]
|
|
|
|
|
super().__init__(
|
|
|
|
|
optim_groups,
|
|
|
|
|
cfg.training.lr,
|
|
|
|
|
cfg.training.adam_betas,
|
|
|
|
|
cfg.training.adam_eps,
|
|
|
|
|
)
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
class VQBeTScheduler(nn.Module):
|
|
|
|
|
def __init__(self, optimizer, cfg):
|
|
|
|
|
super().__init__()
|
|
|
|
|
n_vqvae_training_steps = cfg.training.n_vqvae_training_steps
|
|
|
|
|
|
|
|
|
|
num_warmup_steps = cfg.training.lr_warmup_steps
|
|
|
|
|
num_training_steps = cfg.training.offline_steps
|
|
|
|
|
num_cycles = 0.5
|
|
|
|
|
|
|
|
|
|
def lr_lambda(current_step):
|
|
|
|
|
if current_step < n_vqvae_training_steps:
|
|
|
|
|
return float(1)
|
|
|
|
|
else:
|
|
|
|
|
current_step = current_step - n_vqvae_training_steps
|
|
|
|
|
if current_step < num_warmup_steps:
|
|
|
|
|
return float(current_step) / float(max(1, num_warmup_steps))
|
|
|
|
|
progress = float(current_step - num_warmup_steps) / float(
|
|
|
|
|
max(1, num_training_steps - num_warmup_steps)
|
|
|
|
|
)
|
|
|
|
|
return max(0.0, 0.5 * (1.0 + math.cos(math.pi * float(num_cycles) * 2.0 * progress)))
|
|
|
|
|
|
|
|
|
|
self.lr_scheduler = LambdaLR(optimizer, lr_lambda, -1)
|
|
|
|
|
|
|
|
|
|
def step(self):
|
|
|
|
|
self.lr_scheduler.step()
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
class VQBeTRgbEncoder(nn.Module):
|
|
|
|
|
"""Encode an RGB image into a 1D feature vector.
|
|
|
|
|
|
|
|
|
|
Includes the ability to normalize and crop the image first.
|
|
|
|
|
|
|
|
|
|
Same with DiffusionRgbEncoder from modeling_diffusion.py
|
|
|
|
|
"""
|
|
|
|
|
|
|
|
|
|
def __init__(self, config: VQBeTConfig):
|
|
|
|
|
super().__init__()
|
|
|
|
|
# Set up optional preprocessing.
|
|
|
|
|
if config.crop_shape is not None:
|
|
|
|
|
self.do_crop = True
|
|
|
|
|
# Always use center crop for eval
|
|
|
|
|
self.center_crop = torchvision.transforms.CenterCrop(config.crop_shape)
|
|
|
|
|
if config.crop_is_random:
|
|
|
|
|
self.maybe_random_crop = torchvision.transforms.RandomCrop(config.crop_shape)
|
|
|
|
|
else:
|
|
|
|
|
self.maybe_random_crop = self.center_crop
|
|
|
|
|
else:
|
|
|
|
|
self.do_crop = False
|
|
|
|
|
|
|
|
|
|
# Set up backbone.
|
|
|
|
|
backbone_model = getattr(torchvision.models, config.vision_backbone)(
|
|
|
|
|
weights=config.pretrained_backbone_weights
|
|
|
|
|
)
|
|
|
|
|
# Note: This assumes that the layer4 feature map is children()[-3]
|
|
|
|
|
# TODO(alexander-soare): Use a safer alternative.
|
|
|
|
|
self.backbone = nn.Sequential(*(list(backbone_model.children())[:-2]))
|
|
|
|
|
if config.use_group_norm:
|
|
|
|
|
if config.pretrained_backbone_weights:
|
|
|
|
|
raise ValueError(
|
|
|
|
|
"You can't replace BatchNorm in a pretrained model without ruining the weights!"
|
|
|
|
|
)
|
|
|
|
|
self.backbone = _replace_submodules(
|
|
|
|
|
root_module=self.backbone,
|
|
|
|
|
predicate=lambda x: isinstance(x, nn.BatchNorm2d),
|
|
|
|
|
func=lambda x: nn.GroupNorm(num_groups=x.num_features // 16, num_channels=x.num_features),
|
|
|
|
|
)
|
|
|
|
|
|
|
|
|
|
# Set up pooling and final layers.
|
|
|
|
|
# Use a dry run to get the feature map shape.
|
|
|
|
|
# The dummy input should take the number of image channels from `config.input_shapes` and it should
|
|
|
|
|
# use the height and width from `config.crop_shape` if it is provided, otherwise it should use the
|
|
|
|
|
# height and width from `config.input_shapes`.
|
|
|
|
|
image_keys = [k for k in config.input_shapes if k.startswith("observation.image")]
|
|
|
|
|
assert len(image_keys) == 1
|
|
|
|
|
image_key = image_keys[0]
|
|
|
|
|
dummy_input_h_w = (
|
|
|
|
|
config.crop_shape if config.crop_shape is not None else config.input_shapes[image_key][1:]
|
|
|
|
|
)
|
|
|
|
|
dummy_input = torch.zeros(size=(1, config.input_shapes[image_key][0], *dummy_input_h_w))
|
|
|
|
|
with torch.inference_mode():
|
|
|
|
|
dummy_feature_map = self.backbone(dummy_input)
|
|
|
|
|
feature_map_shape = tuple(dummy_feature_map.shape[1:])
|
|
|
|
|
self.pool = SpatialSoftmax(feature_map_shape, num_kp=config.spatial_softmax_num_keypoints)
|
|
|
|
|
self.feature_dim = config.spatial_softmax_num_keypoints * 2
|
|
|
|
|
self.out = nn.Linear(config.spatial_softmax_num_keypoints * 2, self.feature_dim)
|
|
|
|
|
self.relu = nn.ReLU()
|
|
|
|
|
|
|
|
|
|
def forward(self, x: Tensor) -> Tensor:
|
|
|
|
|
"""
|
|
|
|
|
Args:
|
|
|
|
|
x: (B, C, H, W) image tensor with pixel values in [0, 1].
|
|
|
|
|
Returns:
|
|
|
|
|
(B, D) image feature.
|
|
|
|
|
"""
|
|
|
|
|
# Preprocess: maybe crop (if it was set up in the __init__).
|
|
|
|
|
if self.do_crop:
|
|
|
|
|
if self.training: # noqa: SIM108
|
|
|
|
|
x = self.maybe_random_crop(x)
|
|
|
|
|
else:
|
|
|
|
|
# Always use center crop for eval.
|
|
|
|
|
x = self.center_crop(x)
|
|
|
|
|
# Extract backbone feature.
|
|
|
|
|
x = torch.flatten(self.pool(self.backbone(x)), start_dim=1)
|
|
|
|
|
# Final linear layer with non-linearity.
|
|
|
|
|
x = self.relu(self.out(x))
|
|
|
|
|
return x
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
def _replace_submodules(
|
|
|
|
|
root_module: nn.Module, predicate: Callable[[nn.Module], bool], func: Callable[[nn.Module], nn.Module]
|
|
|
|
|
) -> nn.Module:
|
|
|
|
|
"""
|
|
|
|
|
Args:
|
|
|
|
|
root_module: The module for which the submodules need to be replaced
|
|
|
|
|
predicate: Takes a module as an argument and must return True if the that module is to be replaced.
|
|
|
|
|
func: Takes a module as an argument and returns a new module to replace it with.
|
|
|
|
|
Returns:
|
|
|
|
|
The root module with its submodules replaced.
|
|
|
|
|
"""
|
|
|
|
|
if predicate(root_module):
|
|
|
|
|
return func(root_module)
|
|
|
|
|
|
|
|
|
|
replace_list = [k.split(".") for k, m in root_module.named_modules(remove_duplicate=True) if predicate(m)]
|
|
|
|
|
for *parents, k in replace_list:
|
|
|
|
|
parent_module = root_module
|
|
|
|
|
if len(parents) > 0:
|
|
|
|
|
parent_module = root_module.get_submodule(".".join(parents))
|
|
|
|
|
if isinstance(parent_module, nn.Sequential):
|
|
|
|
|
src_module = parent_module[int(k)]
|
|
|
|
|
else:
|
|
|
|
|
src_module = getattr(parent_module, k)
|
|
|
|
|
tgt_module = func(src_module)
|
|
|
|
|
if isinstance(parent_module, nn.Sequential):
|
|
|
|
|
parent_module[int(k)] = tgt_module
|
|
|
|
|
else:
|
|
|
|
|
setattr(parent_module, k, tgt_module)
|
|
|
|
|
# verify that all BN are replaced
|
|
|
|
|
assert not any(predicate(m) for _, m in root_module.named_modules(remove_duplicate=True))
|
|
|
|
|
return root_module
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
class VqVae(nn.Module):
|
|
|
|
|
def __init__(
|
|
|
|
|
self,
|
|
|
|
|
config: VQBeTConfig,
|
|
|
|
|
):
|
|
|
|
|
"""
|
|
|
|
|
VQ-VAE is composed of three parts: encoder, vq_layer, and decoder.
|
|
|
|
|
Encoder and decoder are MLPs consisting of an input, output layer, and hidden layer, respectively.
|
|
|
|
|
The vq_layer uses residual VQs.
|
|
|
|
|
|
|
|
|
|
This class contains functions for training the encoder and decoder along with the residual VQ layer (for trainign phase 1),
|
|
|
|
|
as well as functions to help BeT training part in training phase 2.
|
|
|
|
|
"""
|
|
|
|
|
|
|
|
|
|
super().__init__()
|
|
|
|
|
self.config = config
|
|
|
|
|
# 'discretized' indicates whether the Residual VQ part is trained or not. (After finishing the training, we set discretized=True)
|
|
|
|
|
self.register_buffer("discretized", torch.tensor(False))
|
|
|
|
|
self.optimized_steps = 0
|
|
|
|
|
# we use the fixed number of layers for Residual VQ across all environments.
|
|
|
|
|
self.vqvae_num_layers = 2
|
|
|
|
|
|
|
|
|
|
self.vq_layer = ResidualVQ(
|
|
|
|
|
dim=config.vqvae_embedding_dim,
|
|
|
|
|
num_quantizers=self.vqvae_num_layers,
|
|
|
|
|
codebook_size=config.vqvae_n_embed,
|
|
|
|
|
)
|
|
|
|
|
|
|
|
|
|
self.encoder = MLP(
|
|
|
|
|
in_channels=self.config.output_shapes["action"][0] * self.config.action_chunk_size,
|
|
|
|
|
hidden_channels=[
|
|
|
|
|
config.vqvae_enc_hidden_dim,
|
|
|
|
|
config.vqvae_enc_hidden_dim,
|
|
|
|
|
config.vqvae_embedding_dim,
|
|
|
|
|
],
|
|
|
|
|
)
|
|
|
|
|
self.decoder = MLP(
|
|
|
|
|
in_channels=config.vqvae_embedding_dim,
|
|
|
|
|
hidden_channels=[
|
|
|
|
|
config.vqvae_enc_hidden_dim,
|
|
|
|
|
config.vqvae_enc_hidden_dim,
|
|
|
|
|
self.config.output_shapes["action"][0] * self.config.action_chunk_size,
|
|
|
|
|
],
|
|
|
|
|
)
|
|
|
|
|
|
|
|
|
|
def get_embeddings_from_code(self, encoding_indices):
|
|
|
|
|
# This function gets code indices as inputs, and outputs embedding vectors corresponding to the code indices.
|
|
|
|
|
with torch.no_grad():
|
|
|
|
|
z_embed = self.vq_layer.get_codebook_vector_from_indices(encoding_indices)
|
|
|
|
|
# since the RVQ has multiple layers, it adds the vectors in the axis of layers to provide a vector for that code combination.
|
|
|
|
|
z_embed = z_embed.sum(dim=0)
|
|
|
|
|
return z_embed
|
|
|
|
|
|
|
|
|
|
def get_action_from_latent(self, latent):
|
|
|
|
|
# given latent vector, this function outputs the decoded action.
|
|
|
|
|
output = self.decoder(latent)
|
|
|
|
|
if self.config.action_chunk_size == 1:
|
|
|
|
|
return einops.rearrange(output, "N (T A) -> N T A", A=self.config.output_shapes["action"][0])
|
|
|
|
|
else:
|
|
|
|
|
return einops.rearrange(output, "N (T A) -> N T A", A=self.config.output_shapes["action"][0])
|
|
|
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def get_code(self, state):
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# in phase 2 of VQ-BeT training, we need a `ground truth labels of action data` to calculate the Focal loss for code prediction head. (please refer to section 3.3 in the paper https://arxiv.org/pdf/2403.03181)
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# this function outputs the `GT code` of given action using frozen encoder and quantization layers. (please refer to Figure 2. in the paper https://arxiv.org/pdf/2403.03181)
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state = einops.rearrange(state, "N T A -> N (T A)")
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with torch.no_grad():
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state_rep = self.encoder(state)
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state_rep_shape = state_rep.shape[:-1]
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state_rep_flat = state_rep.view(state_rep.size(0), -1, state_rep.size(1))
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state_rep_flat, vq_code, vq_loss_state = self.vq_layer(state_rep_flat)
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state_vq = state_rep_flat.view(*state_rep_shape, -1)
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vq_code = vq_code.view(*state_rep_shape, -1)
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vq_loss_state = torch.sum(vq_loss_state)
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return state_vq, vq_code
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def vqvae_forward(self, state):
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# This function passes the given data through Residual VQ with Encoder and Decoder. Please refer to section 3.2 in the paper https://arxiv.org/pdf/2403.03181).
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state = einops.rearrange(state, "N T A -> N (T A)")
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# We start with passing action (or action chunk) at:t+n through the encoder ϕ.
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state_rep = self.encoder(state)
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state_rep_shape = state_rep.shape[:-1]
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state_rep_flat = state_rep.view(state_rep.size(0), -1, state_rep.size(1))
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# The resulting latent embedding vector x = ϕ(at:t+n) is then mapped to an embedding vector in the codebook of the RVQ layers by the nearest neighbor look-up.
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state_rep_flat, vq_code, vq_loss_state = self.vq_layer(state_rep_flat)
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state_vq = state_rep_flat.view(*state_rep_shape, -1)
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vq_code = vq_code.view(*state_rep_shape, -1)
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# since the RVQ has multiple layers, it adds the vectors in the axis of layers to provide a vector for that code combination.
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vq_loss_state = torch.sum(vq_loss_state)
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# Then, the discretized vector zq(x) is reconstructed as ψ(zq(x)) by passing through the decoder ψ.
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dec_out = self.decoder(state_vq)
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# Calculate L1 reconstruction loss
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encoder_loss = (state - dec_out).abs().mean()
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# add encoder reconstruction loss and commitment loss
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rep_loss = encoder_loss + vq_loss_state * 5
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metric = (
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encoder_loss.clone().detach(),
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vq_loss_state.clone().detach(),
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vq_code,
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rep_loss.item(),
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)
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return rep_loss, metric
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class FocalLoss(nn.Module):
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"""
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From https://github.com/notmahi/miniBET/blob/main/behavior_transformer/bet.py
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"""
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def __init__(self, gamma: float = 0, size_average: bool = True):
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super().__init__()
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self.gamma = gamma
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self.size_average = size_average
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def forward(self, input, target):
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if len(input.shape) == 3:
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N, T, _ = input.shape
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logpt = F.log_softmax(input, dim=-1)
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logpt = logpt.gather(-1, target.view(N, T, 1)).view(N, T)
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elif len(input.shape) == 2:
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logpt = F.log_softmax(input, dim=-1)
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logpt = logpt.gather(-1, target.view(-1, 1)).view(-1)
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pt = logpt.exp()
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loss = -1 * (1 - pt) ** self.gamma * logpt
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if self.size_average:
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return loss.mean()
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else:
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return loss.sum()
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class MLP(torch.nn.Sequential):
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def __init__(
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self,
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in_channels: int,
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hidden_channels: List[int],
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):
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layers = []
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in_dim = in_channels
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for hidden_dim in hidden_channels[:-1]:
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layers.append(torch.nn.Linear(in_dim, hidden_dim))
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layers.append(torch.nn.ReLU())
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in_dim = hidden_dim
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layers.append(torch.nn.Linear(in_dim, hidden_channels[-1]))
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super().__init__(*layers)
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Seungjae Lee
GitHub