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如何为ReAct Agent添加线程级内存

先决条件

本指南假设您熟悉以下内容：

本指南将演示如何为预构建的ReAct代理添加内存。请参阅此教程以了解如何开始使用预构建的ReAct代理。

我们可以通过将checkpointer传递给create_react_agent函数来为代理添加内存。

设置

首先，让我们安装所需的包并设置我们的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，可以快速发现并解决您的LangGraph项目中的问题，提高性能。LangSmith允许您使用跟踪数据来调试、测试和监控使用LangGraph构建的LLM应用程序——更多关于如何开始的信息，请参阅这里。

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 typing import Literal

from langchain_core.tools import tool


@tool
def get_weather(city: Literal["nyc", "sf"]):
    """Use this to get weather information."""
    if city == "nyc":
        return "It might be cloudy in nyc"
    elif city == "sf":
        return "It's always sunny in sf"
    else:
        raise AssertionError("Unknown city")


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: ChatOpenAI | tool | MemorySaver | create_react_agent

使用方法

让我们多次与它交互，以展示它可以记住信息。

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.
注意，当我们传递相同的线程 ID 时，聊天历史会被保留。

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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