pages/Anchors.py

# Import Libraries

import pandas as pd
import streamlit as st
import src.prompt_config as prompt_params

# Models
import xgboost
from sklearn.model_selection import train_test_split

# XAI (Explainability)
import shap
import lime
from anchor import anchor_tabular

# Global Variables to Store Model & Data
global_model = None
X_train, X_test, y_train, y_test = None, None, None, None


def train_model():
    """ Train the XGBoost model only once and store it globally. """
    global global_model, X_train, X_test, y_train, y_test
    
    if global_model is None:
        # Load Data from SHAP library
        X, y = shap.datasets.adult()
        
        # Split data
        X_train, X_test, y_train, y_test = train_test_split(X, y, test_size=0.5, random_state=42)
        
        # Train XGBoost model
        global_model = xgboost.XGBClassifier()
        global_model.fit(X_train, y_train)
        
        print("XGBoost Model training completed!")


def define_features():
    """ Define feature names and categorical mappings. """
    
    feature_names = ["Age", "Workclass",
                     "Education-Num", "Marital Status", "Occupation",
                     "Relationship", "Race", "Sex", "Capital Gain",
                     "Capital Loss", "Hours per week", "Country"]
    
    categorical_features = ["Workclass", "Marital Status", "Occupation", "Relationship", "Race", "Sex", "Country"]
    
    class_names = ['<=50K', '>50K']
    
    categorical_names = {
        1: ['Private', 'Self-emp-not-inc', 'Self-emp-inc', 'Federal-gov', 'Local-gov', 'State-gov', 'Without-pay',
            'Never-worked'],
        3: ['Married-civ-spouse', 'Divorced', 'Never-married', 'Separated', 'Widowed', 'Married-spouse-absent',
            'Married-AF-spouse'],
        4: ['Tech-support', 'Craft-repair', 'Other-service', 'Sales', 'Exec-managerial', 'Prof-specialty',
            'Handlers-cleaners',
            'Machine-op-inspct', 'Adm-clerical', 'Farming-fishing', 'Transport-moving', 'Priv-house-serv',
            'Protective-serv', 'Armed-Forces'],
        5: ['Wife', 'Own-child', 'Husband', 'Not-in-family', 'Other-relative', 'Unmarried'],
        6: ['White', 'Asian-Pac-Islander', 'Amer-Indian-Eskimo', 'Other', 'Black'],
        7: ['Female', 'Male'],
        11: ['United-States', 'Cambodia', 'England', 'Puerto-Rico', 'Canada', 'Germany', 'Outlying-US(Guam-USVI-etc)',
             'India',
             'Japan', 'Greece', 'South', 'China', 'Cuba', 'Iran', 'Honduras', 'Philippines', 'Italy', 'Poland',
             'Jamaica', 'Vietnam',
             'Mexico', 'Portugal', 'Ireland', 'France', 'Dominican-Republic', 'Laos', 'Ecuador', 'Taiwan', 'Haiti',
             'Columbia', 'Hungary',
             'Guatemala', 'Nicaragua', 'Scotland', 'Thailand', 'Yugoslavia', 'El-Salvador', 'Trinadad&Tobago', 'Peru',
             'Hong', 'Holand-Netherlands']
    }
    
    return feature_names, categorical_features, class_names, categorical_names


def explain_example(anchors_threshold, example_idx):
    """ Explain a given sample without retraining the model. """
    global global_model, X_train, X_test, y_train, y_test
    
    if global_model is None:
        train_model()
    feature_names, categorical_features, class_names, categorical_names = define_features()

    # Initialize Anchors explainer
    explainer = anchor_tabular.AnchorTabularExplainer(
        class_names,
        feature_names,
        X_train.values,
        categorical_names)
    
    # Explain the selected sample
    exp = explainer.explain_instance(X_test.values[example_idx], global_model.predict, threshold=anchors_threshold)

    explanation_data = {
        "Feature Rule": exp.names(),
        "Precision": [f"{exp.precision():.2f}"] * len(exp.names()),
        "Coverage": [f"{exp.coverage():.2f}"] * len(exp.names())
    }
    df_explanation = pd.DataFrame(explanation_data)
    Prediction = explainer.class_names[global_model.predict(X_test.values[example_idx].reshape(1, -1))[0]]
    st.write(f"### 🔍 The prediction of No. {example_idx} example is: **{Prediction}**")
    st.write("### 📌 Explanation Rules for this example:")
    st.table(df_explanation)


def main():
    global global_model
    
    # Ensure the model is trained only once
    if global_model is None:
        train_model()

    anchors_threshold = st.sidebar.slider(
        label="Set the `Threshold` value:",
        min_value=0.00,
        max_value=1.00,
        value=0.8,  # Default value
        step=0.01,  # Step size
        help=prompt_params.ANCHORS_THRESHOLD_HELP,
    )
    
    example_idx = st.sidebar.number_input(
        label="Select the sample index to explain:",
        min_value=0,
        max_value=len(X_test) - 1,  # Ensures the index is within range
        value=100,  # Default value
        step=1,  # Step size
        help=prompt_params.EXAMPLE_BE_EXPLAINED_IDX,
    )
    st.title("Anchors")
    st.write(prompt_params.ANCHORS_INTRODUCTION)
    # Explain the selected sample
    if st.button("Explain Sample"):
        explain_example(anchors_threshold, example_idx)


if __name__ == '__main__':
    main()