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Getting Started Introduction to LangChain and OpenAI Chat API

This guide provides a clear, concise walkthrough for using LangChain to interact with OpenAI's Chat API. You'll learn to set up your environment, securely configure your API key, and generate responses using LangChain's powerful features.

This tutorial assumes you have an OpenAI API key. We'll demonstrate how to store this key securely within a .env file for best practices.

Before You Begin Prerequisites and Setup

Ensure you have a valid OpenAI API key. Also, make sure you have Python installed on your system.

First, create a new project directory and navigate into it using your terminal.

Package Installation Installing Required Packages

Use pip to install the necessary packages. Open your terminal and run the following command:

```bash pip install langchain openai python-dotenv ```

API Key Configuration Creating a .env File

Create a .env file in your project's root directory. This file will securely store your OpenAI API key. This protects your key from being directly exposed in your code. Add the following line, replacing 'YOUR_OPENAI_API_KEY' with your actual key:

``` OPENAI_API_KEY=YOUR_OPENAI_API_KEY ```

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Python Script Creating the

Create a Python script (e.g., 'main.py') and paste the following code. This script imports the required libraries, loads your API key, and uses LangChain to interact with the OpenAI Chat API.

```python import os from dotenv import load_dotenv from langchain.llms import OpenAI load_dotenv() OPENAI_API_KEY = os.getenv("OPENAI_API_KEY") if not OPENAI_API_KEY: raise ValueError("OpenAI API key not found. Please set the OPENAI_API_KEY environment variable.") llm = OpenAI(openai_api_key=OPENAI_API_KEY, model_name="gpt-3.5-turbo-instruct") # Or any other OpenAI model response = llm("Write a short poem about LangChain.") print(response) ```

Running the Script Executing the Code

Save the Python script. Then, in your terminal, navigate to the directory containing the script and run it using:

```bash python main.py ```

The script will use LangChain and your OpenAI API key to generate a response.

Wrapping Up Conclusion and Next Steps

Congratulations! You've successfully integrated LangChain with the OpenAI Chat API. You've learned the fundamental steps needed to set up your environment, configure your API key securely, and generate text using LangChain.

From here, explore advanced features like prompt templates, different OpenAI models (e.g., GPT-4), and handling different input types to build more complex and interactive applications.