大模型学习记录（八）---------RAG评估

1.从PDF获取数据做RAG

python 复制代码

import os
from langchain.schema import Document
from dotenv import load_dotenv
from langchain_community.vectorstores import FAISS
from langchain.text_splitter import RecursiveCharacterTextSplitter
from langchain_community.embeddings import HuggingFaceBgeEmbeddings, FastEmbedEmbeddings, FakeEmbeddings
import os
import bs4
from dotenv import load_dotenv
from langchain_openai import ChatOpenAI
from langchain_community.document_loaders import WebBaseLoader
from langchain_community.vectorstores import FAISS
from langchain_text_splitters import RecursiveCharacterTextSplitter
from langchain_openai import ChatOpenAI
from langchain.chains import RetrievalQA
from langchain_community.document_loaders import PyPDFLoader
load_dotenv()

# 读取pdf文件



if __name__ == '__main__':
    file_path = r"E:\my_code\llm_system\resource2_RAG\llama2.pdf"
    loader = PyPDFLoader(file_path)
    docs = loader.load()

    # 分割文档, 将文本分割为多个文档片段
    text_splitter = RecursiveCharacterTextSplitter(
        chunk_size=256,                     # 每个文档片段的最大字符数
        chunk_overlap=50,                   # 每个文档片段之间的重叠字符数
    )
    split_docs = text_splitter.split_documents(docs)
    # 对文本进行编码，size和分割文档的chunk_size不是同一个概念，size是每个文档片段的向量维度，常用768，1024
    embedding = FakeEmbeddings(size=768)
    # 对文档片段进行编码
    embeddings = embedding.embed_documents([doc.page_content for doc in split_docs])
    

    # 创建向量存储，使用FAISS.from_embeddings方法
    # 需要创建(text, embedding)元组的列表
    text_embeddings = list(zip([doc.page_content for doc in split_docs], embeddings))
    # 元数据也需要单独提取
    metadatas = [doc.metadata for doc in split_docs]
    vectordb = FAISS.from_embeddings(text_embeddings, embedding, metadatas=metadatas)
    # 也可以使用FAISS.from_documents方法创建向量存储， 使用from_documents方法时，会自动调用模型对象的 .embed_documents() 方法来生成向量
    # vectordb = FAISS.from_documents(split_docs, embedding)
    index_folder_path = "data/faiss_index"

    index_name = "0"

    # 保存索引
    vectordb.save_local(index_folder_path, index_name)

    # 加载索引  allow_dangerous_deserialization 加载由不受信任的源生成的索引文件时需要
    vectordb = FAISS.load_local(index_folder_path, embedding, index_name, allow_dangerous_deserialization=True)

    # 创建检索器
    retriever = vectordb.as_retriever(search_kwargs={"k": 2})
    from langchain_openai import ChatOpenAI

    # 创建模型,API key可以直接写在代码里，也可以从本地环境获取
    api_key = os.getenv("DEEPSEEK_API_KEY")
    llm = ChatOpenAI(temperature=0, model_name="deepseek-chat", api_key=api_key, base_url="https://api.deepseek.com/beta")
    from langchain.chains import RetrievalQA

    # 创建链
    chain = RetrievalQA.from_chain_type(llm=llm,
                                        chain_type="stuff",
                                        retriever=retriever,
                                        return_source_documents=True)

    # 运行链
    response = chain.invoke("什么是llama2")
    print(response)

2.RAG评估

python 复制代码

import os
from langchain.schema import Document
from dotenv import load_dotenv
from langchain_community.vectorstores import FAISS
from langchain.text_splitter import RecursiveCharacterTextSplitter
from langchain_community.embeddings import HuggingFaceBgeEmbeddings, FastEmbedEmbeddings, FakeEmbeddings
import os
import bs4
from dotenv import load_dotenv
from langchain_openai import ChatOpenAI
from langchain_community.document_loaders import WebBaseLoader
from langchain_community.vectorstores import FAISS
from langchain_text_splitters import RecursiveCharacterTextSplitter
from langchain_openai import ChatOpenAI
from langchain.chains import RetrievalQA
from langchain_community.document_loaders import PyPDFLoader
load_dotenv()

# 读取pdf文件



if __name__ == '__main__':
    file_path = r"E:\my_code\llm_system\resource2_RAG\llama2.pdf"
    loader = PyPDFLoader(file_path)
    docs = loader.load()

    # 分割文档, 将文本分割为多个文档片段
    text_splitter = RecursiveCharacterTextSplitter(
        chunk_size=256,                     # 每个文档片段的最大字符数
        chunk_overlap=50,                   # 每个文档片段之间的重叠字符数
    )
    split_docs = text_splitter.split_documents(docs)
    # 对文本进行编码，size和分割文档的chunk_size不是同一个概念，size是每个文档片段的向量维度，常用768，1024
    embedding = FakeEmbeddings(size=768)
    # 对文档片段进行编码
    embeddings = embedding.embed_documents([doc.page_content for doc in split_docs])
    

    # 创建向量存储，使用FAISS.from_embeddings方法
    # 需要创建(text, embedding)元组的列表
    text_embeddings = list(zip([doc.page_content for doc in split_docs], embeddings))
    # 元数据也需要单独提取
    metadatas = [doc.metadata for doc in split_docs]
    vectordb = FAISS.from_embeddings(text_embeddings, embedding, metadatas=metadatas)
    # 也可以使用FAISS.from_documents方法创建向量存储， 使用from_documents方法时，会自动调用模型对象的 .embed_documents() 方法来生成向量
    # vectordb = FAISS.from_documents(split_docs, embedding)
    index_folder_path = "data/faiss_index"

    index_name = "0"

    # 保存索引
    vectordb.save_local(index_folder_path, index_name)

    # 加载索引  allow_dangerous_deserialization 加载由不受信任的源生成的索引文件时需要
    vectordb = FAISS.load_local(index_folder_path, embedding, index_name, allow_dangerous_deserialization=True)

    # 创建检索器
    retriever = vectordb.as_retriever(search_kwargs={"k": 2})
    from langchain_openai import ChatOpenAI

    # 创建模型,API key可以直接写在代码里，也可以从本地环境获取
    api_key = os.getenv("DEEPSEEK_API_KEY")
    os.environ["OPENAI_API_KEY"] = api_key
    llm = ChatOpenAI(temperature=0, model_name="deepseek-chat", api_key=api_key, base_url="https://api.deepseek.com/beta")
    from langchain.chains import RetrievalQA

    # 创建链
    chain = RetrievalQA.from_chain_type(llm=llm,
                                        chain_type="stuff",
                                        retriever=retriever,
                                        return_source_documents=True)

    # 运行链
    # response = chain.invoke("什么是llama2")
    # print(response)


    questions = ["llama2有多少参数？"]

    ground_truths = ["7B、13B和70B"]
    # 生成 answers 和 contexts
    answers = []
    contexts = []

    for question in questions:
        print(question)
        response = chain.invoke(question)
        print(response['result'], "\n")
        answers.append(response['result'])
        contexts.append([doc.page_content for doc in response['source_documents']])

    from datasets import Dataset

    evaluate_data = {
        "question": questions,
        "answer": answers,
        "contexts": contexts,
        "ground_truth": ground_truths
    }

    evaluate_dataset = Dataset.from_dict(evaluate_data)

    # 对Rag进行评估
    from ragas import evaluate
    from ragas.metrics import (
        faithfulness,
        answer_relevancy,
        context_recall,
        context_precision,
    )
    import os
    from ragas.llms import LangchainLLMWrapper
    from langchain_openai import ChatOpenAI, OpenAIEmbeddings

    # 使用gpt-4o作为评估模型，效果更好但成本更高
    evaluator_llm = LangchainLLMWrapper(ChatOpenAI(model_name="deepseek-chat", api_key=api_key, base_url="https://api.deepseek.com/beta"))
    metrics = [
    faithfulness,
    answer_relevancy,
    context_precision,
    context_recall,
    ]

    # 运行评估
    result = evaluate(
        dataset=evaluate_dataset,
        metrics=metrics,
        llm=evaluator_llm,  # 传入自定义的LLM
        embeddings=embedding, # 传入自定义的嵌入模型
    )
    print(result)