train.py

""" 
Trains a Pytorch image classification model using device agonstic code
"""

import os
import torch
import data_setup, engine, model_builder, utils
from torchvision import transforms
from timeit import default_timer as timer 
from pathlib import Path
from get_data import fetch_data
import json




def train_torch():
    # Load config.json
    with open("config.json", "r") as f:
        config = json.load(f)

    # Access configuration parameters
    input_shape = config["input_shape"]
    hidden_units = config["hidden_units"]
  
    # Setup hyperparameters
    NUM_EPOCHS = config["num_epochs"]
    BATCH_SIZE = config["batch_size"]
    LEARNING_RATE = config["learning_rate"]
    
    # Define the URL and paths
    # Define the URL and paths
    url = "https://github.com/mrdbourke/pytorch-deep-learning/raw/main/data/pizza_steak_sushi.zip"
    data_path = Path("/data")
    image_path = Path(data_path / "pizza_steak_sushi")

    # Call the fetch_data function
    fetch_data(url, data_path, image_path)

    # Setup directories
    train_dir = "/data/pizza_steak_sushi/train"
    test_dir = "/data/pizza_steak_sushi/test"

    # Setup target device
    device = "cuda" if torch.cuda.is_available() else "cpu"

    # Create transforms
    data_transform = transforms.Compose([
        transforms.Resize((64, 64)),
        transforms.ToTensor()
    ])

    # Create dataloaders with help from data_Setup.py
    train_dataloader, test_dataloader, class_names = data_setup.create_dataloaders(train_dir=train_dir,
                                                                                    test_dir=test_dir,
                                                                                    transform=data_transform,
                                                                                    batch_size=BATCH_SIZE)
    # Create model with help from model_builder.py
    model = model_builder.TinyVGG(
        input_shape = input_shape,
        hidden_units=hidden_units,
        output_shape=len(class_names)
    ).to(device)

    # Set loss and optimizer
    loss_fn = torch.nn.CrossEntropyLoss()
    optimizer= torch.optim.Adam(model.parameters(),
                                lr=LEARNING_RATE)
    
    # Start the timer
    start_time = timer()

    # Start training with help from engine.py
    results = engine.train(model=model,
                    train_dataloader=train_dataloader,
                    test_dataloader=test_dataloader,
                    loss_fn=loss_fn,
                    optimizer=optimizer,
                    epochs=NUM_EPOCHS,
                    device=device)
    # End the timer and print out how long it took
    end_time = timer()
    print(f"[INFO] Total training time: {end_time-start_time:.3f} seconds")
    print(f"[INFO] results dict: {results}")
    # Save the model with help from utils.py
    utils.save_model(model=model,
                        target_dir="models",
                        model_name="05_going_modular_script_mode_tinyvgg_model.pth")
    
    

if __name__ == '__main__':
    train_torch()