一、LangChain简介
github地址:
GitHub - langchain-ai/langchain: ⚡ Building applications with LLMs through composability ⚡
LangChain是一个用于开发由语言模型支持的应用程序的框架。它使应用程序能够:
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具有上下文感知能力:将语言模型与上下文源连接起来(提示说明、几个镜头示例、响应的内容等)
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推理:依靠语言模型进行推理(关于如何根据提供的上下文回答、采取什么操作等)
该框架由几个部分组成。
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LangChain 库:Python 和 JavaScript 库。包含无数组件的接口和集成、将这些组件组合成链和代理的基本运行时,以及链和代理的现成实现。
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LangChain 模板:一系列易于部署的参考架构,适用于各种任务。
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LangServe:用于将 LangChain 链部署为 REST API 的库。
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LangSmith:一个开发者平台,可让您调试、测试、评估和监控基于任何 LLM 框架构建的链,并与 LangChain 无缝集成。
二、为什么学习LangChain
作为一种专为开发基于语言模型的应用而设计的框架,通过 LangChain,我们不仅可以通过 API 调用如 ChatGPT、GPT-4、Llama 2 等大型语言模型,还可以实现更高级的功能。
真正有潜力且具有创新性的应用,不仅仅在于能通过 API 调用语言模型,更重要的是能够具备以下两个特性:
数据感知:能够将语言模型与其他数据源连接起来,从而实现对更丰富、更多样化数据的理解和利用。
具有代理性:能够让语言模型与其环境进行交互,使得模型能够对其环境有更深入的理解,并能够进行有效的响应。
LangChain 框架的设计目标,是使这种 AI 类型的应用成为可能,并帮助我们最大限度地释放大语言模型的潜能。
三、hello world
安装langchain和openai python包。
pip3 install langchain -i https://pypi.tuna.tsinghua.edu.cn/simple/
pip3 install langchain -i https://pypi.tuna.tsinghua.edu.cn/simple/
Looking in indexes: https://pypi.tuna.tsinghua.edu.cn/simple/
Collecting langchain
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Installing collected packages: urllib3, typing-extensions, tenacity, sniffio, PyYAML, packaging, numpy, mypy-extensions, multidict, jsonpointer, idna, greenlet, frozenlist, exceptiongroup, charset-normalizer, certifi, attrs, async-timeout, annotated-types, yarl, typing-inspect, SQLAlchemy, requests, pydantic-core, marshmallow, jsonpatch, anyio, aiosignal, pydantic, dataclasses-json, aiohttp, langsmith, langchain
Successfully installed PyYAML-6.0.1 SQLAlchemy-2.0.23 aiohttp-3.8.6 aiosignal-1.3.1 annotated-types-0.6.0 anyio-3.7.1 async-timeout-4.0.3 attrs-23.1.0 certifi-2023.7.22 charset-normalizer-3.3.2 dataclasses-json-0.6.2 exceptiongroup-1.1.3 frozenlist-1.4.0 greenlet-3.0.1 idna-3.4 jsonpatch-1.33 jsonpointer-2.4 langchain-0.0.335 langsmith-0.0.64 marshmallow-3.20.1 multidict-6.0.4 mypy-extensions-1.0.0 numpy-1.26.2 packaging-23.2 pydantic-2.5.0 pydantic-core-2.14.1 requests-2.31.0 sniffio-1.3.0 tenacity-8.2.3 typing-extensions-4.8.0 typing-inspect-0.9.0 urllib3-2.1.0 yarl-1.9.2
pip3 install openai -i https://pypi.tuna.tsinghua.edu.cn/simple/
(langchain) D:\>pip3 install openai -i https://pypi.tuna.tsinghua.edu.cn/simple/
Looking in indexes: https://pypi.tuna.tsinghua.edu.cn/simple/
Collecting openai
Downloading https://pypi.tuna.tsinghua.edu.cn/packages/38/ae/0a6b73156176c10ff52b94f5444712bcdb8d22dddf68f106c14f0937e390/openai-1.2.4-py3-none-any.whl (220 kB)
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Installing collected packages: h11, distro, colorama, tqdm, httpcore, httpx, openai
Successfully installed colorama-0.4.6 distro-1.8.0 h11-0.14.0 httpcore-1.0.2 httpx-0.25.1 openai-1.2.4 tqdm-4.66.1
(langchain) D:\>
运行hello world
(langchain) D:\>python
Python 3.10.12 | packaged by conda-forge | (main, Jun 23 2023, 22:34:57) [MSC v.1936 64 bit (AMD64)] on win32
Type "help", "copyright", "credits" or "license" for more information.
>>> import os
>>> os.environ["OPENAI_API_KEY"]="你的open ai apikey"
>>> from langchain.llms import OpenAI
>>> llm = OpenAI(model_name="text-davinci-003",max_tokens=200)
>>> text = llm("请给我写一句情人节红玫瑰的中文宣传语")
>>> print(text)
"让满满的爱意萦绕,红玫瑰给你最美的浪漫祝福!"
>>> text = llm("请给我写一句情人节红玫瑰的中文宣传语")
>>> print(text)
"情深缘浓,玫瑰爱相随!"