LangChain Setup and Usage

Install the LangChain framework and develop AI applications. Chains, memory and tools.

Advanced30 min

Setup Steps

1. Install LangChain via pip:

pip install langchain langchain-openai langchain-community

2. Set environment variables:

export OPENAI_API_KEY="sk-..."
export LANGCHAIN_TRACING_V2=true
export LANGCHAIN_API_KEY="ls__..."

3. Create a simple chain:

python
from langchain_openai import ChatOpenAI
from langchain_core.prompts import ChatPromptTemplate

llm = ChatOpenAI(model="gpt-4o")
prompt = ChatPromptTemplate.from_messages([
    ("system", "You are a helpful assistant."),
    ("user", "{input}")
])
chain = prompt | llm
response = chain.invoke({"input": "Hello!"})
print(response.content)

4. RAG (Retrieval-Augmented Generation) example:

pip install faiss-cpu

5. Document loader usage:

python
from langchain_community.document_loaders import TextLoader
from langchain.text_splitter import RecursiveCharacterTextSplitter
loader = TextLoader('document.txt')
docs = loader.load()
splitter = RecursiveCharacterTextSplitter(chunk_size=1000)
chunks = splitter.split_documents(docs)

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