README.md

```python
from openrlhf.models.model import get_llm_for_sequence_regression
from transformers import AutoTokenizer
from typing import List
import torch
import regex as re
def strip_sequence(text, pad_token, eos_token):
    pad_token_escaped = re.escape(pad_token)
    eos_token_escaped = re.escape(eos_token)

    pattern = f"^({eos_token_escaped}|{pad_token_escaped})+"
    text = re.sub(pattern, "", text)

    pattern = f"({eos_token_escaped}|{pad_token_escaped})+$"
    text = re.sub(pattern, "", text)
    return text

class RewardModelProxy:
    def __init__(
        self, 
        reward_pretrain:str,
        max_len:int,
        batch_size:int,
        normalize_reward:bool=False,
        flash_attn:bool=True,
        bf16:bool=True,
        load_in_4bit:bool=False,
        value_head_prefix:str="score",
        disable_fast_tokenizer:bool=False,
    ):
        
        self.reward_model = get_llm_for_sequence_regression(
            reward_pretrain,
            "reward",
            normalize_reward=normalize_reward,
            use_flash_attention_2=flash_attn,
            bf16=bf16,
            load_in_4bit=load_in_4bit,
            value_head_prefix=value_head_prefix,
            device_map="cuda:5",
        )
        self.reward_model.eval()

        self.tokenizer = AutoTokenizer.from_pretrained(reward_pretrain, trust_remote_code=True, use_fast=not disable_fast_tokenizer)
        self.max_length = max_len
        self.batch_size = batch_size

    def get_reward(self, conversations:List[List[dict]]):
        if self.batch_size is None:
            batch_size = len(conversations)
        else:
            batch_size = self.batch_size
        
        queries = []
        for conversation in conversations:
            query = self.tokenizer.apply_chat_template(conversation, tokenize=False, add_generation_prompt=False)
            queries.append(query)

        # remove pad_token
        for i in range(len(queries)):
            queries[i] = (
                strip_sequence(queries[i], self.tokenizer.pad_token, self.tokenizer.eos_token)
                + self.tokenizer.eos_token
            )

        scores = []
        # batch
        with torch.no_grad():
            for i in range(0, len(queries), batch_size):
                inputs = self.tokenize_fn(
                    queries[i : min(len(queries), i + batch_size)], device=self.reward_model.device
                )
                r = self.reward_model(inputs["input_ids"], inputs["attention_mask"])
                r = r.tolist()
                scores.extend(r)
        return scores

    def tokenize_fn(self, texts, device):
        batch = self.tokenizer(
            texts,
            return_tensors="pt",
            add_special_tokens=False,
            max_length=self.max_length,
            padding=True,
            truncation=True,
        )
        return {k: v.to(device) for k, v in batch.items()}

    def __call__(self, conversations:List[List[dict]]):
        return self.get_reward(conversations)
    
RM = RewardModelProxy(
    "CodeDPO/Qwen2.5-Coder-7B_with_margin_scalebt",
    max_len=2048,
    batch_size=8,
)
conversations = [
    [
        {"role": "system", "content": "Hello, how can I help you today?"},
        {"role": "user", "content": "I want to book a flight."},
    ],
]

scores = RM(conversations)
print(scores)
```