app.py

### 1. Imports and class names setup ###
import gradio as gr
import os
import torch

from model import create_effnetb2_model   # this will create our feature extractor
from timeit import default_timer as timer
from typing import Tuple, Dict

# Setup class names
with open("class_names.txt", "r") as f:
    class_names = [food_name.strip() for food_name in f.readlines()]
    
### 2. Model and transforms preparation ###
# Create model and transforms
effnetb2, effnetb2_transforms = create_effnetb2_model(num_classes=101)

# Load the saved weights
effnetb2.load_state_dict(
    torch.load(f="09_pretrained_effnetb2_feature_extractor_food101_20pct.pth",
              map_location=torch.device("cpu")) # it's important to map to cpu if trained on gpu or it will default to gpu
)

### 3. 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 to add batch dimension
    
    # 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 pred 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

### 4. Gradio app ###

# Create, title, description and article
title = "Test ML title"
description = "this is a test description"
article = "this is a test article"

# Create example list
example_list = [["examples/" + example] for example in os.listdir("examples")]

# Create the Gradio demo
demo = gr.Interface(fn=predict, # maps inputs to outputs
                    inputs=gr.Image(type="pil"),
                    outputs=[gr.Label(num_top_classes=5, label="Predictions"),
                             gr.Number(label="Prediction time (s)")],
                    examples=example_list,
                    title=title,
                    description=description,
                    article=article)

# Launch the demo!
demo.launch()