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GPT-2 Chatbot

Complete Documentation & Project Details for Text Generation & Conversational AI

Project Description

This project implements a GPT-2 chatbot system for text generation and conversational AI. GPT-2 (Generative Pre-trained Transformer 2) uses autoregressive language modeling to generate coherent and contextually relevant text, making it excellent for chatbots and creative text generation. The system includes fine-tuning strategies, response generation, context management, and advanced features like temperature-controlled generation, batch processing, and comprehensive evaluation.

GPT-2 uses transformer decoder architecture with autoregressive generation to produce text one token at a time. The implementation provides complete PyTorch support with Transformers (Hugging Face), comprehensive training pipeline, REST API server, evaluation metrics, and deployment tools for text generation and conversational AI applications.

Project Screenshots

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GPT-2 Chatbot

Core Features

GPT-2 Architecture

  • Autoregressive text generation
  • Transformer decoder layers
  • Pre-trained GPT-2 models (base, medium, large, xl)
  • Fine-tuning for specific domains
  • Natural language generation

Context Management

  • Multi-turn conversation support
  • Session-based context
  • Sliding window context
  • Context-aware responses
  • Conversation history tracking

Text Generation

  • Temperature-controlled generation
  • Top-p (nucleus) sampling
  • Top-k sampling
  • Repetition penalty control
  • Diverse output generation

Batch Generation

  • Batch text generation
  • Multiple prompt processing
  • Efficient GPU utilization
  • JSON and text output formats
  • High-throughput processing

Model Evaluation

  • Perplexity calculation
  • Generation speed metrics
  • BLEU, ROUGE-L, METEOR scores
  • Response quality scoring
  • Comprehensive metrics

REST API Server

  • Flask-based API
  • Multiple endpoints
  • CORS enabled
  • Request logging
  • Production-ready

Advanced Features

Evaluation Metrics

  • BLEU scores (1-4 grams)
  • METEOR score
  • ROUGE-L score
  • Perplexity calculation
  • Batch evaluation support

Data Augmentation

  • Synonym replacement
  • Paraphrasing techniques
  • Noise injection
  • Automated dataset expansion

Response Ranking

  • Multi-factor ranking system
  • Similarity-based (50%)
  • Intent confidence (20%)
  • Sentiment matching (30%)

Conversation Analytics

  • Dataset statistics
  • Word frequency analysis
  • Topic distribution
  • Conversation length analysis
  • Export capabilities

REST API Endpoints

Endpoint Method Description Request Body Response
/api/chat POST Main chat interface {"message": "text", "session_id": "optional"} Generated response with metadata
/api/generate POST Text generation {"prompt": "text", "max_length": 100, "temperature": 0.7} Generated text
/api/batch POST Batch text generation {"prompts": ["text1", "text2"], "max_length": 100} List of generated texts
/api/evaluate POST Evaluate model performance {"test_file": "path", "model": "gpt2"} Perplexity and speed metrics
/api/health GET Health check N/A Server status
/api/clear POST Clear conversation {"session_id": "optional"} Success message

Technologies Used

This GPT-2 chatbot project is built using modern deep learning and web technologies. The core implementation uses Python as the primary programming language, PyTorch for deep learning operations, and the Transformers library from Hugging Face for GPT-2 model integration. The project includes a Flask-based REST API for web integration, Jupyter Notebook support for interactive development and demonstrations, and comprehensive evaluation metrics for assessing model performance.

The GPT-2 model variants (base, medium, large, xl) are provided by Hugging Face, enabling easy access to pre-trained models and fine-tuning capabilities. The system supports autoregressive text generation with temperature control, top-p and top-k sampling, making it suitable for various text generation and conversational AI applications.

Python 3.8+ PyTorch 2.0+ Transformers 4.30+ Hugging Face GPT-2 Text Generation Language Modeling Jupyter Notebook Flask 2.3+ Evaluation Metrics

Installation & Usage

Installation

Install all required dependencies for the GPT-2 chatbot project:

# Install all requirements pip install -r requirements.txt # The GPT-2 model will be automatically downloaded # from Hugging Face on first use

Quick Setup

Set up the project structure and verify installation:

# Run quick setup script python quick_start.py setup # Test imports python quick_start.py test-imports # Run quick test python quick_start.py quick-test

Training the Model

Fine-tune the GPT-2 model on your text dataset:

# Basic training python train.py --train_file data/train.txt --output_dir models/fine_tuned_gpt2 # Training with custom parameters python train.py --train_file data/train.txt \ --output_dir models/fine_tuned_gpt2 \ --epochs 3 \ --batch_size 4 \ --learning_rate 5e-5 \ --model_name gpt2

Interactive Chatbot

Run the chatbot in interactive mode for conversations:

# Run chatbot with default model python chatbot.py # Run with trained model python chatbot.py --fine_tuned_path models/fine_tuned_gpt2 # Run with custom model variant python chatbot.py --model_name gpt2-medium # Commands in chat: # - Type 'quit', 'exit', or 'bye' to end # - Type 'clear' to clear context # - Type 'save' to save conversation # - Type 'load ' to load conversation # - Type 'stats' to see conversation statistics

REST API Server

Start the Flask API server for web integration:

# Start API server (default port 5000) python app.py # API will be available at http://localhost:5000 # Example API calls: # POST /api/chat - {"message": "Hello", "session_id": "user123"} # POST /api/generate - {"prompt": "Once upon a time", "max_length": 100} # POST /api/batch - {"prompts": ["Prompt 1", "Prompt 2"]} # POST /api/evaluate - {"test_file": "data/val.txt", "model": "gpt2"} # GET /api/health # POST /api/clear - {"session_id": "user123"}

Batch Text Generation

Generate text from multiple prompts at once:

# Generate from text file python batch_generate.py --input data/sample_prompts.txt --output results.json # Generate from JSON file python batch_generate.py --input data/sample_prompts.json --output results.json # This will process multiple prompts efficiently # and save results in JSON format

Evaluation Metrics

Evaluate chatbot responses using comprehensive metrics:

from evaluate_model import evaluate_model # Evaluate model on test dataset results = evaluate_model( model_name='gpt2', test_file='data/val.txt', device='cuda' ) # Returns dictionary with: # - perplexity: Language model perplexity # - avg_generation_time: Average generation time per token # - tokens_per_second: Generation speed # - total_tokens: Total tokens processed # Print detailed results for metric, value in results.items(): print(f"{metric}: {value:.4f}") # Advanced evaluation with multiple metrics from advanced_evaluation import AdvancedEvaluator evaluator = AdvancedEvaluator() scores = evaluator.evaluate( reference="Hello, how can I help you?", candidate="Hi there! How may I assist you?" ) # Returns BLEU, ROUGE-L, METEOR, and semantic similarity scores

Metric Descriptions:

  • BLEU (1-4): Measures n-gram precision between reference and candidate
  • METEOR: Considers synonyms and word order, more semantic than BLEU
  • ROUGE-L: Measures longest common subsequence, good for longer responses
  • Perplexity: Measures how well the model predicts the next word

Conversation Analytics

Analyze your conversation dataset:

# Generate conversation statistics python conversation_stats.py # This will display: # - Total conversations # - Word frequency analysis # - Topic distribution # - Conversation length statistics

Export Conversations

Export conversations to various formats:

# Export conversations python export_conversations.py # Exports to: # - CSV format # - Plain text format # - Training format # - Statistics export

Jupyter Notebook

Open the interactive Jupyter notebook for demonstrations:

# Start Jupyter notebook jupyter notebook notebooks/fine_tune_gpt2.ipynb # Or use JupyterLab jupyter lab notebooks/text_generation_demo.ipynb

Project Structure

gpt2-chatbot/
├── README.md # Main documentation
├── requirements.txt # Python dependencies
├── config.py # Configuration settings
├── LICENSE # License file
├── PROJECT_INFO.md # Project overview
│
├── Core Modules
│ ├── chatbot.py # Interactive chatbot
│ ├── generate_text.py # Text generation script
│ ├── batch_generate.py # Batch text generation
│ ├── train.py # Fine-tuning script
│ ├── conversation_manager.py # Conversation management
│ └── utils.py # Utility functions
│
├── Advanced Features
│ ├── advanced_evaluation.py # Advanced evaluation metrics
│ ├── advanced_train.py # Multi-domain training
│ ├── evaluate_model.py # Model evaluation
│ ├── model_comparison.py # Model comparison tools
│ ├── prompt_templates.py # Prompt engineering
│ └── response_quality.py # Response quality scoring
│
├── API & Services
│ ├── app.py # Flask web API
│ └── index.html # Web interface
│
├── Data
│ ├── train.txt # Training data
│ ├── val.txt # Validation data
│ ├── domain_technical.txt # Technical domain data
│ ├── domain_creative.txt # Creative writing samples
│ └── sample_prompts.txt # Sample prompts
│
├── Models
│ └── (trained model checkpoints)
│
├── Notebooks
│ ├── fine_tune_gpt2.ipynb # Fine-tuning notebook
│ └── text_generation_demo.ipynb # Generation demo
│
└── Conversations
└── (saved conversations)

Configuration Options

Model Configuration (config.py)

Customize model and training parameters in config.py:

# Model Configuration MODEL_NAME = "gpt2" # GPT-2 model variant (gpt2, gpt2-medium, gpt2-large, gpt2-xl) MAX_LENGTH = 100 # Maximum generation length BATCH_SIZE = 4 # Training batch size LEARNING_RATE = 5e-5 # Learning rate NUM_EPOCHS = 3 # Number of training epochs WARMUP_STEPS = 100 # Warmup steps for LR scheduler # Generation Parameters TEMPERATURE = 0.7 # Generation temperature (higher = more creative) TOP_P = 0.9 # Nucleus sampling TOP_K = 50 # Top-K sampling REPETITION_PENALTY = 1.2 # Repetition penalty DO_SAMPLE = True # Enable sampling # Chatbot Configuration CONTEXT_LENGTH = 5 # Previous messages in context SYSTEM_PROMPT = "You are a helpful AI assistant."

Advanced Features Usage

Text Generation

Generate text with customizable parameters:

from generate_text import generate_text from config import MODEL_NAME, DEVICE # Generate text from prompt text = generate_text( prompt="Once upon a time", model_name=MODEL_NAME, max_length=100, temperature=0.7, top_p=0.9, top_k=50, device=DEVICE ) # Returns generated text string # Or use the chatbot class from chatbot import GPTChatbot chatbot = GPTChatbot(model_name='gpt2') response = chatbot.generate_response("Hello, how are you?") print(response)

Batch Text Generation

Generate text from multiple prompts efficiently:

from batch_generate import batch_generate # Generate from list of prompts prompts = [ "Once upon a time", "In a galaxy far away", "The future of AI is" ] results = batch_generate( prompts=prompts, model_name='gpt2', max_length=100, output_file='results.json' ) # Returns list of generated texts # Also saves to JSON file with metadata

Model Evaluation

Evaluate model performance with comprehensive metrics:

from evaluate_model import evaluate_model # Evaluate model on test dataset results = evaluate_model( model_name='gpt2', test_file='data/val.txt', device='cuda' ) # Returns dictionary with: # - perplexity: Language model perplexity # - avg_generation_time: Average time per token # - tokens_per_second: Generation speed # - total_tokens: Total tokens processed # Advanced evaluation from advanced_evaluation import AdvancedEvaluator evaluator = AdvancedEvaluator() scores = evaluator.evaluate( reference="Reference text", candidate="Generated text" ) # Returns BLEU, ROUGE-L, METEOR, semantic similarity

Model Comparison

Compare different GPT-2 variants to find the best model:

from model_comparison import compare_models # Compare different GPT-2 variants models = ['gpt2', 'gpt2-medium', 'gpt2-large'] results = compare_models( models=models, test_prompts=["Prompt 1", "Prompt 2"], max_length=100 ) # Returns comparison with: # - Generation quality scores # - Generation speed # - Memory usage # - Model size # Helps choose best model for your use case

Advanced Prompt Engineering

Use pre-built templates and custom prompts for optimized generation:

from prompt_templates import PromptTemplates templates = PromptTemplates() # Use pre-built templates prompt = templates.get_template('creative_writing') # Returns: "Write a creative story about: {topic}" # Custom prompt builder custom_prompt = templates.build_prompt( style='technical', context='machine learning', instruction='explain' ) # Available templates: # - creative_writing, technical, conversational # - question_answer, summarization, translation

API Usage Examples

Chat Endpoint (cURL)

Send a chat message and get response with intent and sentiment:

curl -X POST http://localhost:5000/api/chat \ -H "Content-Type: application/json" \ -d '{ "message": "Hello, what is GPT-2?", "session_id": "user123" }' # Response: # { # "response": "GPT-2 is a transformer model...", # "session_id": "user123", # "timestamp": "2025-01-15T10:30:00" # }

Text Generation (cURL)

Generate text from a prompt:

curl -X POST http://localhost:5000/api/generate \ -H "Content-Type: application/json" \ -d '{ "prompt": "Once upon a time", "max_length": 100, "temperature": 0.7 }' # Response: # { # "generated_text": "Once upon a time, in a land far away...", # "length": 100 # }

Batch Generation (cURL)

Generate text from multiple prompts:

curl -X POST http://localhost:5000/api/batch \ -H "Content-Type: application/json" \ -d '{ "prompts": ["Prompt 1", "Prompt 2", "Prompt 3"], "max_length": 100 }' # Response: # { # "results": [ # {"prompt": "Prompt 1", "generated": "..."}, # {"prompt": "Prompt 2", "generated": "..."} # ] # }

Model Evaluation (cURL)

Evaluate model performance:

curl -X POST http://localhost:5000/api/evaluate \ -H "Content-Type: application/json" \ -d '{ "test_file": "data/val.txt", "model": "gpt2" }' # Response: # { # "perplexity": 25.3, # "avg_generation_time": 0.05, # "tokens_per_second": 20.0 # }

Python Requests Example

Use the API with Python requests library:

import requests # Chat endpoint response = requests.post( 'http://localhost:5000/chat', json={ 'message': 'Hello, how are you?', 'session_id': 'user123' } ) data = response.json() print(f"Bot: {data['response']}") print(f"Intent: {data['intent']}") print(f"Sentiment: {data['sentiment']}") # Get context context = requests.get('http://localhost:5000/context/user123') print(context.json()) # Clear context requests.delete('http://localhost:5000/context/user123')

GPT-2 Model Variants

Model Parameters Size Use Case Speed
gpt2 117M ~500 MB Fast inference, basic tasks Fastest
gpt2-medium 345M ~1.4 GB Balanced quality/speed Fast
gpt2-large 762M ~3.0 GB Higher quality generation Moderate
gpt2-xl 1.5B ~6.0 GB Best quality, research Slower

Dataset Information

Training Datasets

The project includes multiple domain-specific datasets for fine-tuning:

  • General training data (train.txt, val.txt)
  • Technical domain data
  • Creative writing samples
  • Conversation samples (Q&A pairs)
  • Science & technology topics
  • Business & economics content
  • Health & wellness topics
  • Education & learning content
  • Philosophy & ethics topics
  • History & culture content
  • Sample prompts (text and JSON formats)
  • Advanced training examples

Data Format

Training data is stored in plain text format (one example per line):

# train.txt format (one example per line) Machine learning is a subset of artificial intelligence. GPT-2 is a transformer-based language model. Natural language processing enables computers to understand text. Deep learning uses neural networks with multiple layers. Text generation creates coherent sequences of words. # For batch generation, JSON format: [ {"prompt": "Once upon a time", "max_length": 100}, {"prompt": "In a galaxy far away", "max_length": 100} ]

Adding Custom Training Data

Add your own text data for fine-tuning:

# Simply append to training file with open('data/train.txt', 'a', encoding='utf-8') as f: f.write("Your custom training text here.\n") f.write("Each line is a separate training example.\n") f.write("The model will learn from these examples.\n") # Or create a new domain-specific file with open('data/domain_custom.txt', 'w', encoding='utf-8') as f: f.write("Domain-specific training data...\n") # Use in training python train.py --train_file data/domain_custom.txt --output_dir models/custom

Troubleshooting & Best Practices

Common Issues

  • CUDA Out of Memory: Reduce batch_size in config.py, use smaller model (gpt2 instead of gpt2-large), or use CPU mode
  • Model Not Found: Ensure GPT-2 model downloads correctly from Hugging Face on first run
  • Slow Generation: Use smaller model (gpt2 or gpt2-medium) or reduce max_length
  • API Connection Error: Check if app.py is running on port 5000
  • Import Errors: Verify all dependencies installed: pip install -r requirements.txt
  • Context Too Long: Reduce CONTEXT_LENGTH in config.py or MAX_LENGTH
  • Repetitive Output: Adjust temperature (higher) or repetition_penalty (higher) in config.py

Best Practices

  • Training Data: Use diverse, high-quality text data for better results
  • Context Management: Keep CONTEXT_LENGTH between 3-7 for optimal performance
  • Batch Size: Use smaller batches (4-8) for limited GPU memory, especially with larger models
  • Learning Rate: Start with 5e-5 and adjust based on training loss
  • Temperature: Use 0.7-0.9 for creative text, 0.3-0.5 for more focused output
  • Model Selection: Start with gpt2 for speed, use gpt2-medium or larger for quality
  • Evaluation: Regularly evaluate perplexity on validation set during training
  • Session Management: Use unique session_ids for different users
  • API Rate Limiting: Implement rate limiting for production deployments
  • Logging: Monitor training logs for debugging and optimization

Performance Optimization

  • GPU Usage: Set CUDA_VISIBLE_DEVICES for multi-GPU systems
  • Model Selection: Use gpt2 for fastest inference, larger models for better quality
  • Batch Processing: Use batch_generate.py for processing multiple prompts efficiently
  • Caching: Cache model and tokenizer to avoid reloading
  • Context Pruning: Remove old context beyond CONTEXT_LENGTH
  • Generation Parameters: Adjust temperature, top_p, and top_k for desired output style

Contact Information

Get in Touch

Developer: Molla Samser
Designer & Tester: Rima Khatun

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help@rskworld.in support@rskworld.in
+91 93305 39277

License

This project is for educational purposes only. See LICENSE file for more details.

About RSK World

Founded by Molla Samser, with Designer & Tester Rima Khatun, RSK World is your one-stop destination for free programming resources, source code, and development tools.

Founder: Molla Samser
Designer & Tester: Rima Khatun

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