How to install Langchain on an M2 Macbook

and develop a simple Q/A app.

Photo by Patrick Tomasso on Unsplash

Recently I started playing with Langchain, which is a popular framework for large language models. Langchain enables you to quickly create a chatbot (or an agent) by using OpenAI’s ChatGPT.

While installing Langchain on an M2 Macbook is quite straightforward with:

pip install langchain

The problem arose later on when I tried to develop a simple app, which answers questions from a text document:

import os
import glob
from langchain.document_loaders import TextLoader
from langchain.indexes import VectorstoreIndexCreator
from langchain.chat_models import ChatOpenAI

os.environ['OPENAI_API_KEY'] = OPENAI_API_KEY

loader_list = []
for filepath in glob.glob('*.txt'):
    print(filepath)
    loader = TextLoader(filepath)
    loader_list.append(loader)

index = VectorstoreIndexCreator().from_loaders(loader_list)

def answer_promth(prompt):
    return index.query(prompt, llm=ChatOpenAI())

The chroma DB is the AI-native open-source embedding database. The app uses it for memory.

While running the code above on an M2 Macbook you might encounter an error:

ValueError: Could not import chromadb python package. Please install it with `pip install chromadb`.

If you’re a Python developer, you know that the solution is to run to install the missing dependency:

pip install chromadb

But you might encounter another error while installing it:

note: This error originates from a subprocess, and is likely not a problem with pip.
  ERROR: Failed building wheel for hnswlib
Failed to build hnswlib
ERROR: Could not build wheels for hnswlib, which is required to install pyproject.toml-based projects

The solution that worked for me was to install conda with miniforge:

brew install miniforge
conda init zsh
conda activate base
conda install chromadb

Then the installation works out of the box.

Let me know if this solution also worked for you.