app.py

### 1. Imports and class names setup ###
import gradio as gr
import os
import torch
from pathlib import Path
from zipfile import ZipFile
from model import create_effnetb2_model
from timeit import default_timer as timer
from typing import Tuple, Dict

# Setup class names
class_names = ['pizza', 'steak', 'sushi']

### 2. Handle examples.zip ###
# Define the zip file and the target extraction folder
zip_file_path = Path("examples.zip")
extracted_folder_path = Path("examples")

# Extract .zip file if it exists and is not already extracted
if zip_file_path.exists() and not extracted_folder_path.exists():
    print(f"Extracting {zip_file_path} to {extracted_folder_path}...")
    with ZipFile(zip_file_path, "r") as zf:
        zf.extractall(extracted_folder_path)
    print(f"Extraction complete. Files extracted to {extracted_folder_path}.")
else:
    print(f"ZIP file not found or examples folder already exists.")

### 3. Model and transforms preparation ###
effnetb2, effnetb2_transforms = create_effnetb2_model(num_classes=3)

# Load saved weights
effnetb2.load_state_dict(
    torch.load(
        f="09_pretrained_effnetb2_feature_extractor_pizza_steak_sushi_20_percent.pth",
        map_location=torch.device("cpu")  # Load the model to the CPU
    )
)

### 4. Predict function ###

def predict(img) -> Tuple[Dict, float]:
    # Start a timer
    start_time = timer()

    # Transform the input image for use with EffNetB2
    img = effnetb2_transforms(img).unsqueeze(0)  # unsqueeze = add batch dimension on 0th index

    # Put model into eval mode, make prediction
    effnetb2.eval()
    with torch.inference_mode():
        # Pass transformed image through the model and turn the prediction logits into probabilities
        pred_probs = torch.softmax(effnetb2(img), dim=1)

    # Create a prediction label and prediction probability dictionary
    pred_labels_and_probs = {class_names[i]: float(pred_probs[0][i]) for i in range(len(class_names))}

    # Calculate prediction time
    end_time = timer()
    pred_time = round(end_time - start_time, 4)

    # Return pred dict and pred time
    return pred_labels_and_probs, pred_time

### 5. Gradio app ###

# Create title, description, and article
title = "Food Extractor 🍕🥩🍣"
description = "An [EfficientNetB2 feature extractor](https://pytorch.org/vision/stable/models/generated/torchvision.models.efficientnet_b2.html#torchvision.models.efficientnet_b2) computer vision model to classify images as pizza, steak or sushi."
article = "Created by [Prof. Sajad Ahmad Rather, IIT Roorkee, PARIMAL LAB](https://github.com/SajadAHMAD1)."

# Create example list
example_list = [[str(filepath)] for filepath in extracted_folder_path.glob("*")]  # Get all files in the examples folder

# Create the Gradio demo
demo = gr.Interface(fn=predict,  # Maps inputs to outputs
                    inputs=gr.Image(type="pil"),
                    outputs=[gr.Label(num_top_classes=3, label="Predictions"),
                             gr.Number(label="Prediction time (s)")],
                    examples=example_list,
                    title=title,
                    description=description,
                    article=article)

# Launch the demo!
demo.launch(debug=False)  # Don't need share=True in Hugging Face Spaces