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2026-07-13 12:47:19 +08:00

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Python

# Copyright Lightning AI. Licensed under the Apache License 2.0, see LICENSE file.
"""Implementation derived from https://github.com/tloen/alpaca-lora"""
import os
from dataclasses import dataclass, field
import torch
from torch.utils.data import DataLoader, random_split
from litgpt.data import DataModule, SFTDataset, get_sft_collate_fn
from litgpt.prompts import PromptStyle
from litgpt.tokenizer import Tokenizer
@dataclass
class LIMA(DataModule):
"""LIMA data module for supervised finetuning."""
mask_prompt: bool = False
"""Whether to mask the prompt section from the label (with ``ignore_index``)."""
val_split_fraction: float = 0.1
"""The fraction of the dataset to use for the validation dataset. The rest is used for training."""
prompt_style: str | PromptStyle = "alpaca"
"""The style to apply to instruction prompts. See `litgpt.prompts` for a list of available styles."""
ignore_index: int = -100
"""The index to use for elements to be ignored in the label."""
seed: int = 42
"""The random seed for creating the train/val splits and shuffling the dataset."""
num_workers: int = 4
"""How many DataLoader processes to use for loading."""
include_multiturn_conversations: bool = False
"""Whether to include multi-turn conversations in the dataset."""
repo_id: str = "GAIR/lima"
"""The Hugging Face dataset repository ID from where to download the data."""
access_token: str | None = field(repr=False, default=os.getenv("HF_TOKEN"))
"""The Hugging Face API token to use for authentication. Can also be set through the
`HF_TOKEN` environment variable."""
tokenizer: Tokenizer | None = field(default=None, init=False, repr=False)
batch_size: int = field(default=1, init=False, repr=False)
max_seq_length: int = field(default=-1, init=False, repr=False)
train_dataset: SFTDataset | None = field(default=None, init=False, repr=False)
test_dataset: SFTDataset | None = field(default=None, init=False, repr=False)
def __post_init__(self):
super().__init__()
if self.access_token is None:
raise ValueError(
"LIMA requires authentication, please set the `HF_TOKEN=your_token` environment"
" variable or pass --access_token=your_token. You can find your token by visiting"
" https://huggingface.co/settings/tokens"
)
if isinstance(self.prompt_style, str):
self.prompt_style = PromptStyle.from_name(self.prompt_style)
def connect(
self, tokenizer: Tokenizer | None = None, batch_size: int = 1, max_seq_length: int | None = None
) -> None:
self.tokenizer = tokenizer
self.batch_size = batch_size
self.max_seq_length = -1 if max_seq_length is None else max_seq_length
def prepare_data(self) -> None:
from datasets import load_dataset
load_dataset(self.repo_id, token=self.access_token)
def setup(self, stage: str = "") -> None:
from datasets import load_dataset
dataset = load_dataset(self.repo_id, token=self.access_token)
data = format_dataset(dataset["train"], self.include_multiturn_conversations)
# Partition the dataset into train and test
train_data, test_data = random_split(
data,
[1.0 - self.val_split_fraction, self.val_split_fraction],
generator=torch.Generator().manual_seed(self.seed),
)
train_data, test_data = list(train_data), list(test_data)
self.train_dataset = SFTDataset(
data=train_data,
tokenizer=self.tokenizer,
prompt_style=self.prompt_style,
max_seq_length=self.max_seq_length,
mask_prompt=self.mask_prompt,
ignore_index=self.ignore_index,
)
self.test_dataset = SFTDataset(
data=test_data,
tokenizer=self.tokenizer,
prompt_style=self.prompt_style,
max_seq_length=self.max_seq_length,
mask_prompt=self.mask_prompt,
ignore_index=self.ignore_index,
)
def train_dataloader(self) -> DataLoader:
return DataLoader(
self.train_dataset,
batch_size=self.batch_size,
shuffle=True,
generator=torch.Generator().manual_seed(self.seed),
num_workers=self.num_workers,
collate_fn=get_sft_collate_fn(max_seq_length=self.max_seq_length, ignore_index=self.ignore_index),
)
def val_dataloader(self) -> DataLoader:
return DataLoader(
self.test_dataset,
batch_size=self.batch_size,
shuffle=False,
num_workers=self.num_workers,
collate_fn=get_sft_collate_fn(max_seq_length=self.max_seq_length, ignore_index=self.ignore_index),
)
def format_dataset(dataset_partition: dict, include_multi_turn_conversations: bool) -> list[dict]:
formatted_ds = []
for entry in dataset_partition:
convo = entry["conversations"]
if include_multi_turn_conversations:
for i in range(0, len(convo) - 1, 2):
formatted_ds.append({"instruction": convo[i], "input": "", "output": convo[i + 1]})
else:
formatted_ds.append({"instruction": convo[0], "input": "", "output": convo[1]})
return formatted_ds