rl_code/examples/reward_function/ocr_vqa.py

import re
from typing import Any, Dict, List, Optional
from collections import Counter


def extract_boxed_answer(text: str) -> Optional[str]:
    """
    从文本中提取\boxed{}或\\boxed{}中的答案
    支持多种boxed格式：\boxed{answer}, \\boxed{answer}, \box{answer}
    """
    if not text:
        return None
    
    # 匹配各种boxed格式的正则表达式，按优先级排序
    patterns = [
        r'\\\\boxed\{([^}]*)\}',  # \\boxed{answer} (两个反斜杠)
        r'\\boxed\{([^}]*)\}',    # \boxed{answer} (一个反斜杠)
        r'\\\\box\{([^}]*)\}',    # \\box{answer} (两个反斜杠)
        r'\\box\{([^}]*)\}',      # \box{answer} (一个反斜杠)
        r'boxed\{([^}]*)\}',      # boxed{answer} (无反斜杠)
        r'box\{([^}]*)\}',        # box{answer} (无反斜杠)
    ]
    
    for pattern in patterns:
        matches = re.findall(pattern, text, re.IGNORECASE)
        if matches:
            # 返回最后一个匹配的答案（通常是最终答案）
            return matches[-1].strip()
    
    return None


def extract_answer_from_response(response: str) -> str:
    """
    从响应中提取答案，优先提取boxed答案，如果没有则使用整个响应
    """
    if not response:
        return ""
    
    # 首先尝试提取boxed答案
    boxed_answer = extract_boxed_answer(response)
    if boxed_answer:
        return boxed_answer
    
    # 如果没有boxed格式，尝试其他提取策略
    response = response.strip()
    
    # 寻找常见的答案模式
    answer_patterns = [
        r'(?:answer|final answer|result|solution)[\s\:]*(.+?)(?:\n|$)',
        r'(?:the answer is)[\s\:]*(.+?)(?:\n|$)',
        r'(?:therefore|thus|so)[\s\,]*(.+?)(?:\n|$)',
    ]
    
    for pattern in answer_patterns:
        matches = re.findall(pattern, response, re.IGNORECASE | re.MULTILINE)
        if matches:
            return matches[-1].strip()
    
    # 如果都没找到，返回最后一行或整个响应
    lines = response.split('\n')
    non_empty_lines = [line.strip() for line in lines if line.strip()]
    
    if non_empty_lines:
        return non_empty_lines[-1]
    
    return response


def normalize_text(text: str) -> str:
    """标准化文本用于比较，移除多余空格、标点符号并转换为小写"""
    if not text:
        return ""
    
    # 转换为小写并去除首尾空格
    text = text.lower().strip()
    
    # 移除多余的空白字符
    text = re.sub(r'\s+', ' ', text)
    
    return text.strip()

def token_f1_reward(norm_response: str, norm_ground_truth: str) -> float:
    """基于词袋重叠的 token 级 F1。输入应为已规范化文本。"""
    if not norm_response and not norm_ground_truth:
        return 1.0
    if not norm_response or not norm_ground_truth:
        return 0.0

    response_tokens = norm_response.split()
    ground_truth_tokens = norm_ground_truth.split()

    if not response_tokens or not ground_truth_tokens:
        return 0.0

    response_counts = Counter(response_tokens)
    ground_truth_counts = Counter(ground_truth_tokens)
    common_token_count = sum((response_counts & ground_truth_counts).values())

    if common_token_count == 0:
        return 0.0

    precision = common_token_count / sum(response_counts.values())
    recall = common_token_count / sum(ground_truth_counts.values())

    if precision + recall == 0:
        return 0.0

    return 2 * precision * recall / (precision + recall)


def accuracy_reward(extracted_response: str, ground_truth: str) -> tuple[float, float]:
    """标准化后先尝试直接匹配；不相等则回退到 token 级 F1。"""
    norm_response = normalize_text(extracted_response)
    norm_ground_truth = normalize_text(ground_truth)

    if norm_response == norm_ground_truth:
        return 1.0, 1.0

    return token_f1_reward(norm_response, norm_ground_truth), 0.0


def format_reward(response: str) -> float:
    """检查是否能从boxed格式中提取出答案"""
    if not response or not response.strip():
        return 0.0
    
    # 尝试从boxed格式中提取答案
    extracted_answer = extract_boxed_answer(response)
    
    if extracted_answer is not None and extracted_answer.strip():
        return 1.0  # 成功提取到非空答案
    elif extracted_answer is not None:
        return 0.5  # 有boxed格式但答案为空
    else:
        return 0.0  # 没有boxed格式



def compute_score(reward_inputs: List[Dict[str, Any]], format_weight: float = 0.1) -> List[Dict[str, float]]:
    """
    计算OCR-VQA响应的奖励分数，支持boxed格式的答案提取
    
    Args:
        reward_inputs: 包含response和ground_truth的字典列表
        format_weight: 格式分数的权重（默认0.1）- 检查是否能从boxed中提取答案
        
    Returns:
        包含各种分数的字典列表
    """
    if not isinstance(reward_inputs, list):
        raise ValueError("Please use `reward_type=batch` for OCR-VQA reward function.")
    
    scores = []
    for reward_input in reward_inputs:
        response = reward_input["response"].strip()
        ground_truth = extract_answer_from_response(reward_input["ground_truth"].strip())
        
        # 检查format reward
        format_score = format_reward(response)
        # 提取答案用于详细评估
        extracted_answer = extract_answer_from_response(response)
        # 计算各项分数
        accuracy_score, standard_acc = accuracy_reward(extracted_answer, ground_truth)

        # 计算加权总分
        overall_score = (1 - format_weight) * accuracy_score + format_weight * format_score
        
        scores.append({
            "overall": overall_score,
            "accuracy": accuracy_score,
            "format": format_score,
            "standard_acc": standard_acc,
        })
    
    return scores