app.py

# Import necessary libraries
import numpy as np
import joblib  # For loading the serialized model
import pandas as pd  # For data manipulation
from flask import Flask, request, jsonify  # For creating the Flask API
from flask_cors import CORS


# Initialize the Flask application
rental_price_predictor_api = Flask("Airbnb Rental Price Predictor")

CORS(rental_price_predictor_api)  # Enable CORS for all routes


# Load the trained machine learning model
model = joblib.load("rental_price_prediction_model_v1_0.joblib")

# Define a route for the home page (GET request)
@rental_price_predictor_api.get('/')
def home():
    """
    This function handles GET requests to the root URL ('/') of the API.
    It returns a simple welcome message.
    """
    return "Welcome to the Airbnb Rental Price Prediction API!"

# Define an endpoint for single property prediction (POST request)
@rental_price_predictor_api.post('/v1/rental')
def predict_rental_price():
    """
    This function handles POST requests to the '/v1/rental' endpoint.
    It expects a JSON payload containing property details and returns
    the predicted rental price as a JSON response.
    """
    # Get the JSON data from the request body
    property_data = request.get_json()

    # Extract relevant features from the JSON data
    sample = {
        'room_type': property_data['room_type'],
        'accommodates': property_data['accommodates'],
        'bathrooms': property_data['bathrooms'],
        'cancellation_policy': property_data['cancellation_policy'],
        'cleaning_fee': property_data['cleaning_fee'],
        'instant_bookable': property_data['instant_bookable'],
        'review_scores_rating': property_data['review_scores_rating'],
        'bedrooms': property_data['bedrooms'],
        'beds': property_data['beds']
    }

    # Convert the extracted data into a Pandas DataFrame
    input_data = pd.DataFrame([sample])

    # Make prediction (get log_price)
    predicted_log_price = model.predict(input_data)[0]

    # Calculate actual price
    predicted_price = np.exp(predicted_log_price)

    # Convert predicted_price to Python float
    predicted_price = round(float(predicted_price), 2)
    # The conversion above is needed as we convert the model prediction (log price) to actual price using np.exp, which returns predictions as 
    ## NumPy float32 values.
    # When we send this value directly within a JSON response, Flask's jsonify function encounters a datatype error

    # Return the actual price
    return jsonify({'Predicted Price (in dollars)': predicted_price})


# Define an endpoint for batch prediction (POST request)
@rental_price_predictor_api.post('/v1/rentalbatch')
def predict_rental_price_batch():
    """
    This function handles POST requests to the '/v1/rentalbatch' endpoint.
    It expects a CSV file containing property details for multiple properties
    and returns the predicted rental prices as a dictionary in the JSON response.
    """
    # Get the uploaded CSV file from the request
    file = request.files['file']

    # Read the CSV file into a Pandas DataFrame
    input_data = pd.read_csv(file)

    # Make predictions for all properties in the DataFrame (get log_prices)
    predicted_log_prices = model.predict(input_data).tolist()

    # Calculate actual prices
    predicted_prices = [round(float(np.exp(log_price)), 2) for log_price in predicted_log_prices]

    # Create a dictionary of predictions with property IDs as keys
    property_ids = input_data['id'].tolist()  # Assuming 'id' is the property ID column
    output_dict = dict(zip(property_ids, predicted_prices))  # Use actual prices

    # Return the predictions dictionary as a JSON response
    return output_dict

# Run the Flask application in debug mode if this script is executed directly
if __name__ == '__main__':
    rental_price_predictor_api.run(debug=True)