app.py

import gradio as gr
import pandas as pd
import numpy as np
import pickle
import shap
import matplotlib.pyplot as plt

# Load model
with open("salar_xgb_team.pkl", "rb") as f:
    model = pickle.load(f)

# Set up SHAP
explainer = shap.Explainer(model)

# Define prediction function
def predict_salary(age, education_num, sex, capital_gain, capital_loss, hours_per_week):
    sex_num = 0 if sex == "Male" else 1
    input_data = pd.DataFrame([[age, education_num, sex_num, capital_gain, capital_loss, hours_per_week]],
                              columns=['age', 'education-num', 'sex', 'capital-gain', 'capital-loss', 'hours-per-week'])

    # Prediction & confidence
    pred = model.predict(input_data)[0]
    prob = model.predict_proba(input_data)[0][1]
    label = ">50K" if pred == 1 else "<=50K"
    confidence = f"{prob * 100:.2f}%" if pred == 1 else f"{(1 - prob) * 100:.2f}%"

    # SHAP values
    shap_values = explainer(input_data)
    fig, ax = plt.subplots(figsize=(6, 2.5))
    shap.plots.bar(shap_values[0], max_display=6, show=False)
    plt.tight_layout()
    
    return label, confidence, fig

# Build UI
with gr.Blocks(theme=gr.themes.Soft()) as demo:
    gr.Markdown("## 💼 Income Prediction App")
    gr.Markdown(
        """
        This tool uses a trained XGBoost model to predict whether someone earns more than $50K/year based on demographic and financial information.
        It also shows which features influenced the prediction the most, using SHAP explainability.
        """
    )

    with gr.Row():
        with gr.Column():
            age = gr.Number(label="Age", value=35)
            education = gr.Number(label="Education Level (numeric)", value=10)
            sex = gr.Radio(["Male", "Female"], label="Sex", value="Male")
            cap_gain = gr.Number(label="Capital Gain", value=0)
            cap_loss = gr.Number(label="Capital Loss", value=0)
            hours = gr.Number(label="Hours per Week", value=40)
            submit_btn = gr.Button("🔮 Predict")

        with gr.Column():
            result = gr.Label(label="Predicted Income")
            confidence = gr.Label(label="Prediction Confidence")
            shap_plot = gr.Plot(label="Feature Importance (SHAP)")

    gr.Markdown("### 🧪 Try Example Inputs")
    gr.Examples(
        examples=[
            [24, 9, "Female", 0, 0, 25],
            [45, 13, "Male", 5000, 0, 50],
            [39, 10, "Female", 0, 0, 35],
            [60, 16, "Male", 0, 0, 40],
        ],
        inputs=[age, education, sex, cap_gain, cap_loss, hours],
    )

    submit_btn.click(fn=predict_salary,
                     inputs=[age, education, sex, cap_gain, cap_loss, hours],
                     outputs=[result, confidence, shap_plot])

demo.launch()