python：字典反转

import json
import os

def reverse_drug_mapping():
    """
    反转药物ID和序号的映射关系并保存到新文件
    
    从 node2id.json 读取 {drugbank_id: 药物序号} 的映射，
    反转为 {药物序号: drugbank_id} 并保存到 id2node.json
    """
    # 定义文件路径
    input_path = r"D:\LLaMA-Factory\data\drugbank_smiles\node2id.json"
    output_path = r"D:\LLaMA-Factory\data\drugbank_smiles\id2node.json"
    
    # 1. 读取原始JSON文件
    with open(input_path, 'r', encoding='utf-8') as f:
        node2id = json.load(f)
    # 2. 反转字典映射 {drugbank_id: 药物序号} -> {药物序号: drugbank_id}
    id2node = {v: k for k, v in node2id.items()}
    
    
    # 4. 将反转后的字典写入新JSON文件
    with open(output_path, 'w', encoding='utf-8') as f:
        json.dump(id2node, f, indent=4, ensure_ascii=False)
            

if __name__ == "__main__":
    reverse_drug_mapping()