Installing LangChain

LangChain is not just one library; it is a Chain of Ecosystems. In early 2024, LangChain moved to a modular structure to make it lighter and faster.

1. Modular Structure

As and AI developer, you should understand the three main parts of LangChain:

• langchain-core: The base abstractions (interfaces) for models, prompts, and chains.
• langchain-community: Third-party integrations (Postgres, Pinecone, specific search engines).
• langchain: The higher-level chains and systems that tie everything together.

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2. The Basic Installation

To get started with the standard features, run:

pip install langchain

This will automatically install langchain-core and common utility libraries.

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3. Best Practice: requirements.txt

Never install packages manually without recording them. Create a file named requirements.txt and add:

langchain

Then install using:

pip install -r requirements.txt

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4. Verification

To ensure LangChain is installed correctly, you can run a quick check in Python:

import langchain
print(f"LangChain version: {langchain.__version__}")

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Key Takeaways

• LangChain is Modular; you only install what you need.
• pip install langchain is the entry point for most users.
• Use a requirements.txt file to manage your project's history.
• Installation verification is a crucial step in every setup.