app.py

import torch
import torch.nn as nn
from torchvision import models
import gradio as gr
from PIL import Image
import os
from typing import List, Dict, Union

from custom_transformer.vit import ViT
from transforms import model_transforms

class GradioApp:

    def __init__(self) -> None:

        device = 'cuda' if torch.cuda.is_available() else 'cpu'

        custom = ViT().to(device).eval()
        custom.load_state_dict(torch.load('models/my_vit.pt', map_location=device))
        
        pretrained = models.vit_b_16().to(device).eval()
        pretrained.heads = nn.Linear(768, 3)
        pretrained.load_state_dict(torch.load('models/pretrained_vit.pt', map_location=device))

        self.models: Dict[str, Union[str, nn.Module]] = {
            'Custom': custom,
            'Pretrained': pretrained
        }
        with open('classname.txt') as f:
            self.classes: List[str] = [line.strip() for line in f.readlines()]
    
    def predict(self, img_file: str, model_name: str) -> Dict[str, float]:
        
        img = model_transforms[model_name](Image.open(img_file)).unsqueeze(0)
        with torch.inference_mode():
            preds = torch.softmax(self.models[model_name](img)[0], dim=0).cpu().numpy()
        return dict(zip(self.classes, preds))
    
    def launch(self):
    
        dataset_url = 'https://www.kaggle.com/datasets/marquis03/bean-leaf-lesions-classification/data'
        github_repo_url = 'https://github.com/i4ata/TransformerClassification'
        examples_list = [['examples/' + example] for example in os.listdir('examples')]

        demo = gr.Interface(
            fn=self.predict,
            inputs=[
                gr.Image(type='filepath', label='Input image to classify'), 
                gr.Radio(choices=('Custom', 'Pretrained'), label='Available models')
            ],
            outputs=gr.Label(num_top_classes=3, label='Model predictions'),
            examples=examples_list,
            cache_examples=False,
            title='Plants Diseases Classification',
            description=f'This model performs classification on images of leaves that are either healthy, \
                have bean rust, or have an angular leaf spot. A vision transformer neural network architecture is used. \
                The dataset can be downloaded from [Kaggle]({dataset_url}) and the source code is on [GitHub]({github_repo_url}).',
        )
        demo.launch()

if __name__ == '__main__':
    app = GradioApp()
    app.launch()