colossalai

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from typing import Optional
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import torch.nn as nn
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from transformers.models.gpt2.configuration_gpt2 import GPT2Config
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from transformers.models.gpt2.modeling_gpt2 import GPT2Model
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from ..base import Critic
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class GPTCritic(Critic):
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    """
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    GPT Critic model.
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    Args:
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        pretrained (str): Pretrained model name or path.
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        config (GPT2Config): Model config.
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        lora_rank (int): Rank of the LO-RA decomposition.
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        lora_train_bias (str): LoRA bias training mode.
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    """
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    def __init__(
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        self,
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        pretrained: Optional[str] = None,
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        config: Optional[GPT2Config] = None,
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        lora_rank: int = 0,
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        lora_train_bias: str = "none",
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        **kwargs,
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    ) -> None:
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        if pretrained is not None:
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            model = GPT2Model.from_pretrained(pretrained)
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        elif config is not None:
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            model = GPT2Model(config)
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        else:
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            model = GPT2Model(GPT2Config())
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        value_head = nn.Linear(model.config.n_embd, 1)
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        super().__init__(model, value_head, lora_rank, lora_train_bias, **kwargs)
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