Mastering GPT-3: A Comprehensive Guide to Fine-Tuning with OpenAI, Complete with Examples

Kapil Khatik
10 min readFeb 18, 2023

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Introduction

Before diving into fine-tuning a GPT-3 model, it’s important to understand what a language model is and how GPT-3 works.

A language model is a type of artificial intelligence algorithm that can generate and understand human language. It works by predicting the next word or sequence of words in a given piece of text, based on the words that have come before it.

GPT-3 (Generative Pre-trained Transformer 3) is a large, powerful language model developed by OpenAI that has been trained on a massive corpus of text data. It has been trained using a transformer architecture, which is a type of neural network that is designed to handle sequential data, such as natural language.

Because of its massive size and extensive training, GPT-3 is capable of performing a wide variety of language-based tasks, including text generation, text completion, translation, and more.

However, GPT-3 is a general-purpose language model, which means it has been trained on a broad range of data and doesn’t have specific knowledge about any particular domain or task. This is where fine-tuning comes in.

By fine-tuning a GPT-3 model on a specific task or domain, you can customize it to perform better on that task, making it more accurate and effective. This is done by feeding the model with examples specific to the task, which allows it to learn the patterns and rules that are relevant to that task.

What does fine-tuning a GPT-3 model mean?

Fine-tuning a GPT-3 model means training the pre-trained GPT-3 language model on a specific task or domain to improve its performance on that task.

GPT-3 is a large pre-trained language model that has been trained on a vast amount of diverse data. Fine-tuning allows you to adapt the pre-trained model to a specific task, such as sentiment analysis, machine translation, question answering, or any other language-based task.

During fine-tuning, you start with the pre-trained GPT-3 model and train it further on a smaller dataset that is specific to the task at hand. This process involves initializing the pre-trained model with the pre-trained weights and then fine-tuning the model’s parameters on the smaller dataset.

The fine-tuning process typically involves several rounds of training, where the model’s performance is evaluated on a validation set to determine if further training is necessary. Once the model achieves satisfactory performance on the validation set, it can be used to generate predictions on a new test set.

Fine-tuning a GPT-3 model can improve its accuracy and effectiveness for specific tasks, making it a powerful tool for natural language processing applications.

Creating Synthetic Data for Machine Learning with GPT-3: A Guide

Synthetic data is artificially created data that can be used to train machine learning models when real-world data is not available or to test models when real-world data is not suitable. In this guide, we’ll explore how to create synthetic data with GPT-3, a text generator that can be used to generate text based on prompts.

Here are the steps to create synthetic data with GPT-3:

  1. Define a prompt or series of prompts that will be used to generate the synthetic data.
  2. Feed the prompt into the GPT-3 text generator to generate the synthetic data.
  3. Alternatively, use a question generator to create a list of questions about a topic, which can be used to generate training data or test a person’s knowledge about a certain topic.
  4. Use the synthetic data to train and test machine learning models by splitting the data into training and test sets.

Synthetic data can be a valuable tool for training and testing machine learning models. It can be used when real data is not available or when you want to protect the privacy of people whose data you are using. Additionally, synthetic data can be generated for any purpose you can imagine, making it a versatile tool that can be used in many different ways.

What makes GPT-3 fine-tuning better than prompting?

  • Fine-tuning GPT-3 on a specific task allows the model to adapt to the task’s patterns and rules, resulting in more accurate and relevant outputs.
  • Prompting GPT-3 with a task-specific input can generate related but suboptimal results.
  • Fine-tuning helps GPT-3 generalize better to new examples, as it can learn the underlying patterns and structures of the task.
  • Fine-tuning enables GPT-3 to achieve better performance and accuracy, especially for complex or specialized tasks.
  • Fine-tuning allows you to customize GPT-3 for a specific domain or industry, which can be highly valuable for businesses and organizations.

Advantages of Fine-Tuning a GPT-3 Model

Fine-tuning a GPT-3 model can provide a number of advantages, including:

  1. Enhanced Accuracy: By training the model on specific tasks or datasets, it can improve performance, leading to greater accuracy.
  2. Improved Robustness: A fine-tuned model is more robust, meaning it’s less prone to overfitting than a non-fine-tuned model. This is particularly useful when dealing with limited data.
  3. Better Generalization: Fine-tuning can lead to better generalization to new data, particularly for complex tasks or datasets.
  4. Increased Interpretability: Fine-tuning can improve a model’s interpretability, making it easier to understand how it works and what it has learned.

GPT-3 Fine tuning pricing

The cost of fine-tuning a model is 50% of the cost of the model being fine-tuned. The current fine-tuning rates for GPT-3 models vary based on the specific model being fine-tuned, similar to the rates for model usage.

What does a GPT-3 fine-tuning dataset typically include?

A GPT-3 fine-tuning training dataset typically consists of a set of examples that are specific to the task or domain that you want to fine-tune the model on. The size and format of the dataset can vary depending on the task and the complexity of the data.

  • For a text classification task, the dataset might consist of a set of labeled examples, where each example is a piece of text and a corresponding label indicating the category or class that the text belongs to.
  • For a language generation task, the dataset might consist of a set of text prompts and corresponding target outputs, which the model will use to learn how to generate text that matches the target output for a given prompt.
  • For a question-answering task, the dataset might consist of a set of questions and their corresponding answers, which the model will use to learn how to generate accurate answers to similar questions.
  • For a language translation task, the dataset might consist of a set of parallel text examples in two languages, which the model will use to learn how to translate text from one language to another.

Here are a couple of examples to illustrate what a GPT-3 fine-tuning training dataset might look like for different tasks:

  1. Text classification: Suppose you want to fine-tune GPT-3 to classify news articles into categories such as sports, politics, and entertainment. You might create a dataset that consists of a set of labeled news articles from different sources, where each article is associated with a category label. For example:
Article: “Lionel Messi scores hat-trick as Barcelona win against Real Madrid.”
Category: Sports
Article: “Donald Trump announces new tariffs on Chinese imports.”
Category: Politics
Article: “Taylor Swift wins Album of the Year at the Grammys.”
Category: Entertainment

2. Language generation: Suppose you want to fine-tune GPT-3 to generate product descriptions for an online shopping website. You might create a dataset that consists of a set of text prompts and corresponding target outputs. For example:

Prompt: “Please write a product description for a portable blender.”
Target output: “This sleek and compact blender is perfect for on-the-go smoothies and shakes. Its powerful motor and durable blades make it easy to blend even tough ingredients, while its lightweight design and rechargeable battery make it ideal for travel and outdoor adventures.”
Prompt: “Please write a product description for a smartwatch.”
Target output: “Stay connected and organized with our stylish and feature-packed smartwatch. With its intuitive touch screen and advanced health monitoring capabilities, this watch is the perfect companion for busy professionals and fitness enthusiasts. Its long-lasting battery and water-resistant design make it a reliable choice for any activity.”

These are just a couple of examples, and the format and size of the dataset will vary depending on the specific task and the complexity of the data.
The training dataset has to be in jsonl format where each document is separated by a new line.

GPT-3 Fine tuning Steps

Step 1: Prepare the Training Dataset

The first step in fine-tuning GPT-3 is to prepare a training dataset that is specific to your use case. This dataset should consist of a large collection of text data that is relevant to the task or domain you are targeting. The format of the dataset will vary depending on the specific task, but it typically consists of a set of text prompts and corresponding target outputs. The dataset can be prepared in any text format, but for ease of use, many people prefer to use the JSONL (JSON Lines) format.

For example, if you want to fine-tune GPT-3 to generate product descriptions for an online shopping website, you might prepare a dataset that consists of a set of text prompts (e.g., “Please write a product description for a portable blender”) and corresponding target outputs (e.g., “This sleek and compact blender is perfect for on-the-go smoothies and shakes…”). You can use any method you prefer to collect and curate the dataset, such as web scraping or manual data entry.

What does a typical JSONL file for a GPT-3 fine-tuning dataset look like?

{"prompt": "<prompt text>", "completion": "<ideal generated text>"}
{"prompt": "<prompt text>", "completion": "<ideal generated text>"}
{"prompt": "<prompt text>", "completion": "<ideal generated text>"}
....

Step 2: Train a New Fine-tuned Model

Once you have prepared your training dataset, you can use it to train a new fine-tuned model. This involves providing the dataset to GPT-3 as input and allowing it to adjust its weights to improve its performance on the specific task. This process can take several hours or even days, depending on the size of the dataset and the complexity of the task.

For example,

import openai
import requests

openai.api_key = “INSERT_YOUR_API_KEY_HERE”

def fine_tune_model(prompt, dataset, model_engine=”davinci”, num_epochs=3, batch_size=4):

headers = {
“Content-Type”: “application/json”,
“Authorization”: f”Bearer {openai.api_key}”,
}

data = {
“model”: f”{model_engine}-0",
“dataset”: dataset,
“prompt”: prompt,
“num_epochs”: num_epochs,
“batch_size”: batch_size
}

url = “https://api.openai.com/v1/fine-tunes"
response = requests.post(url, headers=headers, json=data)

if response.status_code != 200:
raise ValueError(“Failed to fine-tune the model.”)

# Get the ID of the fine-tuned model
model_id = response.json()[“model_id”]
return model_id

The fine_tune_model function takes in the following parameters:

  • prompt: A string containing the text prompt to use for fine-tuning.
  • dataset: The name of the training dataset to use for fine-tuning.
  • model_engine: The name of the GPT-3 model to use for fine-tuning. Default is 'davinci'.
  • num_epochs: The number of epochs to use for fine-tuning. Default is 3.
  • batch_size: The batch size to use for fine-tuning. Default is 4.

The function returns the ID of the fine-tuned GPT-3 model, which can then be used in subsequent API calls.

Note that you will need to replace INSERT_YOUR_API_KEY_HERE with your actual OpenAI API key in order to use this code. Additionally, you should make sure that your API key has the fine-tune scope enabled.

Accessing Fine-Tuned GPT-3 Models Using the OpenAI API: A Step-by-Step Guide

Here are the steps to access the fine-tuned GPT-3 model using the OpenAI API after you have obtained its ID from the fine_tune_model function:

  1. Set your OpenAI API key using openai.api_key = "YOUR_API_KEY".
  2. Call the openai.Completion.create() function to generate text completions from the fine-tuned model. You will need to provide the ID of the fine-tuned model as the model parameter and your prompt as the prompt parameter.

Here is an example of how to use the openai.Completion.create() function to generate text from a fine-tuned GPT-3 model:

import openai

openai.api_key = "YOUR_API_KEY"
fine_tuned_model_id = "YOUR_FINE_TUNED_MODEL_ID"
prompt = "YOUR_PROMPT"

response = openai.Completion.create(
model=fine_tuned_model_id,
prompt=prompt,
max_tokens=100
)

output_text = response.choices[0].text
print(output_text)

In this example, the model parameter is set to fine_tuned_model_id (the ID of the fine-tuned model), and the prompt parameter is set to prompt. The max_tokens parameter sets the maximum number of tokens that the model should generate in response to the prompt.

The openai.Completion.create() function returns a JSON object containing a list of possible text completions. In this example, we are using response.choices[0].text to retrieve the text of the first completion in the list.

Note that you will need to replace YOUR_API_KEY and YOUR_FINE_TUNED_MODEL_ID with your actual API key and the ID of your fine-tuned model, respectively.

Conclusion

Fine-tuning a GPT-3 model with Python can significantly improve its performance on a specific task. The model can be adjusted or “tuned” to better suit the task at hand, resulting in increased accuracy, robustness, generalization, and interpretability.

Furthermore, fine-tuning can reduce the amount of data required to train a model for a specific task, making the process more efficient. However, it is essential to consider the quality of the dataset and the parameters of the model that will be adjusted during the fine-tuning process.

It is also important to monitor the performance of the model during and after fine-tuning. By carefully considering these factors, one can create a high-quality, fine-tuned GPT-3 model.

Ultimately, the decision to fine-tune a model or rely on prompt designing depends on the specific use case. It is recommended to try out various methods and GPT-3 engines to determine the approach that yields the highest quality outputs across a variety of scenarios.

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Kapil Khatik

Passionate about Python & Machine Learning | Fostering innovation in the AI space.