app.py

import gradio as gr
import tensorflow as tf
import keras
import numpy as np
import pickle
from tensorflow.keras.preprocessing.sequence import pad_sequences
import re
import os

# Define and register the custom Perplexity metric
@keras.saving.register_keras_serializable(package="Custom")
class Perplexity(keras.metrics.Metric):
    def __init__(self, name='perplexity', dtype=None, **kwargs):
        super().__init__(name=name, dtype=dtype, **kwargs)
        self.cross_entropy = keras.metrics.Mean(name='cross_entropy')
        
    def update_state(self, y_true, y_pred, sample_weight=None):
        # Calculate cross-entropy
        cross_entropy_values = tf.keras.losses.sparse_categorical_crossentropy(y_true, y_pred)
        # Update the internal mean metric
        self.cross_entropy.update_state(cross_entropy_values, sample_weight)
        
    def result(self):
        # Perplexity is the exponential of the cross-entropy
        return tf.exp(self.cross_entropy.result())
    
    def reset_state(self):
        self.cross_entropy.reset_state()
    
    def get_config(self):
        config = super().get_config()
        return config

# Text cleaning function
def clean_text(text):
    text = re.sub(r'[^\w\s.,!?]', '', text)
    text = re.sub(r'\b\d+\b', '', text)
    text = text.replace('co2', 'carbon dioxide')
    text = text.lower()
    text = ' '.join(text.split())
    return text

# Load models and tokenizers
def load_models():
    print("Loading models and tokenizers...")
    
    # Load models with custom objects for Perplexity
    custom_objects = {'Perplexity': Perplexity}
    
    try:
        with keras.saving.custom_object_scope(custom_objects):
            classifier_model = keras.models.load_model('classifier_model.keras')
            textgen_model = keras.models.load_model('textgen_model.keras')
        
        print("Models loaded successfully with custom objects")
    except Exception as e:
        print(f"Error loading models with custom objects: {e}")
        raise
    
    # Load tokenizers
    try:
        with open('classifier_tokenizer.pkl', 'rb') as handle:
            classifier_tokenizer = pickle.load(handle)
        
        with open('textgen_tokenizer.pkl', 'rb') as handle:
            textgen_tokenizer = pickle.load(handle)
        
        print("Tokenizers loaded successfully")
    except Exception as e:
        print(f"Error loading tokenizers: {e}")
        raise
    
    return classifier_model, classifier_tokenizer, textgen_model, textgen_tokenizer

# Classification function
def classify_text(text, model, tokenizer):
    cleaned_text = clean_text(text)
    sequence = tokenizer.texts_to_sequences([cleaned_text])
    padded = pad_sequences(sequence, maxlen=255, padding='pre')
    prediction = model.predict(padded)[0]
    
    # Get the highest probability class
    class_idx = np.argmax(prediction)
    classes = ['Science', 'Maths', 'History']
    confidence = prediction[class_idx] * 100
    
    return classes[class_idx], confidence

# Text generation function
def generate_text(prompt, model, tokenizer, max_length=50, temperature=0.7):
    cleaned_prompt = clean_text(prompt)
    input_text = cleaned_prompt
    
    for _ in range(max_length):
        token_list = tokenizer.texts_to_sequences([input_text])[0]
        token_list = pad_sequences([token_list], maxlen=255, padding='pre')
        
        predicted = model.predict(token_list, verbose=0)[0]
        
        # Apply temperature
        predicted = np.log(predicted) / temperature
        exp_preds = np.exp(predicted)
        predicted = exp_preds / np.sum(exp_preds)
        
        # Sample from the distribution
        predicted_index = np.random.choice(len(predicted), p=predicted)
        
        output_word = ""
        for word, index in tokenizer.word_index.items():
            if index == predicted_index:
                output_word = word
                break
        
        if output_word == "":
            break
            
        input_text += " " + output_word
    
    return input_text

# Print environment info for debugging
print(f"TensorFlow version: {tf.__version__}")
print(f"Keras version: {tf.keras.__version__}")
print(f"Current directory contents: {os.listdir('.')}")

# Load models with error handling
try:
    print("Starting model loading process...")
    classifier_model, classifier_tokenizer, textgen_model, textgen_tokenizer = load_models()
    print("Models and tokenizers loaded successfully")
except Exception as e:
    print(f"Error in model loading process: {e}")
    raise

# Create Gradio interface functions
def classify_interface(text):
    subject, confidence = classify_text(text, classifier_model, classifier_tokenizer)
    return f"Subject: {subject} (Confidence: {confidence:.2f}%)"

def generate_interface(prompt, length=50, temp=0.7):
    return generate_text(prompt, textgen_model, textgen_tokenizer, max_length=int(length), temperature=float(temp))

# Define example inputs for the classifier
classifier_examples = [
    ["The process of photosynthesis converts light energy into chemical energy, producing oxygen as a byproduct."],
    ["The Pythagorean theorem states that in a right-angled triangle, the square of the length of the hypotenuse equals the sum of squares of the other two sides."],
    ["The Industrial Revolution began in Great Britain in the late 18th century and spread to other parts of Europe and North America."],
    ["Atoms consist of a nucleus containing protons and neutrons, surrounded by electrons that orbit in energy levels."],
    ["Differential equations are mathematical equations that relate a function with its derivatives, representing rates of change."],
    ["The Treaty of Versailles was signed in 1919, officially ending World War I and imposing harsh penalties on Germany."]
]

# Define example inputs for the text generator
generator_examples = [
    ["Newton's laws of motion explain", 30, 0.8],
    ["Climate change affects ecosystems by", 20, 0.7],
    ["Quantum mechanics revolutionized physics when", 20, 0.9],
    ["Chemical reactions occur when", 25, 0.6]
]

# Create Gradio interface
with gr.Blocks(title="Science Text Analyzer") as demo:
    gr.Markdown("# Science Text Analyzer")
    
    with gr.Tab("Classify Text"):
        gr.Markdown("### Classify Academic Text")
        gr.Markdown(
            "The **Science Text Analyzer** uses an **LSTM-based text classification model** trained on curated academic datasets sourced from **Hugging Face**. "
            "It predicts whether input text belongs to **Science**, **Mathematics**, or **History**, leveraging **sequential context** and **language structure** for accurate subject classification."
        )
        with gr.Row():
            with gr.Column():
                text_input = gr.Textbox(label="Enter Text", lines=5, placeholder="Paste a sentence or paragraph here...")
                classify_button = gr.Button("Classify")
            with gr.Column():
                output = gr.Textbox(label="Classification Result", placeholder="The predicted subject and confidence will appear here.")
        
        # Add examples for the classifier
        gr.Examples(
            examples=classifier_examples,
            inputs=text_input,
            outputs=output,
            fn=classify_interface,
            cache_examples=True
        )
        
        classify_button.click(fn=classify_interface, inputs=text_input, outputs=output)
    
    with gr.Tab("Generate Text"):
        gr.Markdown("### Generate Academic Text")
        gr.Markdown(
            "Use this tool to generate educational text based on a given prompt. "
            "You can control the output length and creativity using the sliders below. "
            "**Note:** Longer text lengths will take more time to generate, so please be patient when requesting extensive outputs."
            )

        with gr.Row():
            with gr.Column():
                prompt_input = gr.Textbox(label="Enter a Prompt", lines=3, placeholder="Type an introductory sentence or concept...")
                length_slider = gr.Slider(minimum=10, maximum=60, value=50, step=10, label="Maximum Length (words)")
                temp_slider = gr.Slider(minimum=0.1, maximum=1.5, value=0.7, step=0.1, label="Temperature (Creativity Level)")
                generate_button = gr.Button("Generate")
            with gr.Column():
                generated_output = gr.Textbox(label="Generated Text", lines=8, placeholder="The generated text will appear here.")
        
        # Add examples for the text generator
        gr.Examples(
            examples=generator_examples,
            inputs=[prompt_input, length_slider, temp_slider],
            outputs=generated_output,
            fn=generate_interface,
            cache_examples=True
        )
        
        generate_button.click(fn=generate_interface, inputs=[prompt_input, length_slider, temp_slider], outputs=generated_output)

    gr.Markdown("### About This App")
    gr.Markdown(
    "The **Science Text Analyzer** uses deep learning models trained on curated academic datasets to classify and generate content "
    "related to academic disciplines. The **classifier** categorizes input text into one of three subjects: **Science**, **Mathematics**, or **History**. "
    "The **text generator** produces coherent scientific passages, especially focused on **Physics**, **Chemistry**, and **Biology**, making it a valuable tool "
    "for **educational research**, **content creation**, and **curriculum support**."
)

# Launch the app
demo.launch()