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如何为 ReAct 代理添加线程级内存

前提条件

本指南假设你熟悉以下内容：

本指南将展示如何为预构建的 ReAct 代理添加内存。有关如何开始使用预构建的 ReAct 代理，请参阅本教程。

我们可以通过将检查点器传递给 create_react_agent 函数，为代理添加内存。

安装设置

首先，让我们安装所需的软件包并设置我们的 API 密钥。

%%capture --no-stderr
%pip install -U langgraph langchain-openai

import getpass
import os


def _set_env(var: str):
    if not os.environ.get(var):
        os.environ[var] = getpass.getpass(f"{var}: ")


_set_env("OPENAI_API_KEY")

为 LangGraph 开发设置 LangSmith

注册 LangSmith 以快速发现问题并提升你的 LangGraph 项目的性能。LangSmith 允许你使用跟踪数据来调试、测试和监控使用 LangGraph 构建的大语言模型应用程序 — 点击 此处 了解更多关于如何开始使用的信息。

代码

# First we initialize the model we want to use.
from langchain_openai import ChatOpenAI

model = ChatOpenAI(model="gpt-4o", temperature=0)


# For this tutorial we will use custom tool that returns pre-defined values for weather in two cities (NYC & SF)

from langchain_core.tools import tool


@tool
def get_weather(location: str) -> str:
    """Use this to get weather information."""
    if any([city in location.lower() for city in ["nyc", "new york city"]]):
        return "It might be cloudy in nyc"
    elif any([city in location.lower() for city in ["sf", "san francisco"]]):
        return "It's always sunny in sf"
    else:
        return f"I am not sure what the weather is in {location}"


tools = [get_weather]

# We can add "chat memory" to the graph with LangGraph's checkpointer
# to retain the chat context between interactions
from langgraph.checkpoint.memory import MemorySaver

memory = MemorySaver()

# Define the graph

from langgraph.prebuilt import create_react_agent

graph = create_react_agent(model, tools=tools, checkpointer=memory)

API Reference: tool

使用方法

让我们与它进行多次交互，以展示它能够记住信息。 

def print_stream(stream):
    for s in stream:
        message = s["messages"][-1]
        if isinstance(message, tuple):
            print(message)
        else:
            message.pretty_print()


config = {"configurable": {"thread_id": "1"}}
inputs = {"messages": [("user", "What's the weather in NYC?")]}

print_stream(graph.stream(inputs, config=config, stream_mode="values"))

================================ Human Message =================================

What's the weather in NYC?
================================== Ai Message ==================================
Tool Calls:
  get_weather (call_xM1suIq26KXvRFqJIvLVGfqG)
 Call ID: call_xM1suIq26KXvRFqJIvLVGfqG
  Args:
    city: nyc
================================= Tool Message =================================
Name: get_weather

It might be cloudy in nyc
================================== Ai Message ==================================

The weather in NYC might be cloudy.
请注意，当我们传递相同的线程 ID 时，聊天历史记录会被保留。

inputs = {"messages": [("user", "What's it known for?")]}
print_stream(graph.stream(inputs, config=config, stream_mode="values"))

================================ Human Message =================================

What's it known for?
================================== Ai Message ==================================

New York City (NYC) is known for a variety of iconic landmarks, cultural institutions, and vibrant neighborhoods. Some of the most notable aspects include:

1. **Statue of Liberty**: A symbol of freedom and democracy.
2. **Times Square**: Known for its bright lights, Broadway theaters, and bustling atmosphere.
3. **Central Park**: A large urban park offering a green oasis in the middle of the city.
4. **Empire State Building**: An iconic skyscraper with an observation deck offering panoramic views of the city.
5. **Broadway**: Famous for its world-class theater productions.
6. **Wall Street**: The financial hub of the United States.
7. **Museums**: Including the Metropolitan Museum of Art, the Museum of Modern Art (MoMA), and the American Museum of Natural History.
8. **Diverse Cuisine**: A melting pot of culinary experiences from around the world.
9. **Cultural Diversity**: A rich tapestry of cultures, languages, and traditions.
10. **Fashion**: A global fashion capital, home to New York Fashion Week.

These are just a few highlights of what makes NYC a unique and vibrant city.

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