app.py

import streamlit as st
import pandas as pd
import numpy as np
import matplotlib.pyplot as plt
import seaborn as sns
from sklearn.model_selection import train_test_split
from sklearn.preprocessing import StandardScaler, LabelEncoder
from sklearn.tree import DecisionTreeClassifier
from sklearn.ensemble import RandomForestClassifier
from xgboost import XGBClassifier
from sklearn.inspection import permutation_importance
from sklearn.feature_selection import mutual_info_classif
import io
import base64

# Function to create a download link
def get_download_link(data, filename, text):
    b64 = base64.b64encode(data).decode()
    href = f'<a href="data:file/csv;base64,{b64}" download="{filename}">{text}</a>'
    return href

# Function to plot correlation matrix
def plot_correlation_matrix(data):
    plt.figure(figsize=(12, 10))
    sns.heatmap(data.corr(), annot=True, cmap='coolwarm', linewidths=0.5)
    plt.title('Correlation Matrix')
    plt.tight_layout()
    st.pyplot(plt)

# Function to calculate feature importance
def calculate_feature_importance(X, y):
    # Encode non-sequential class labels to sequential integers
    le = LabelEncoder()
    y_encoded = le.fit_transform(y)  # Transform y into continuous integers

    # Split the dataset
    X_train, X_test, y_train, y_test = train_test_split(X, y_encoded, test_size=0.2, random_state=42)
    
    scaler = StandardScaler()
    X_train_scaled = scaler.fit_transform(X_train)
    X_test_scaled = scaler.transform(X_test)

    methods = {
        "Decision Tree": DecisionTreeClassifier(random_state=42),
        "Random Forest": RandomForestClassifier(n_estimators=100, random_state=42),
        "XGBoost": XGBClassifier(random_state=42)
    }

    importance_dict = {}

    for name, model in methods.items():
        model.fit(X_train_scaled, y_train)
        importance_dict[name] = model.feature_importances_

    # Permutation Importance
    rf = RandomForestClassifier(n_estimators=100, random_state=42)
    rf.fit(X_train_scaled, y_train)
    perm_importance = permutation_importance(rf, X_test_scaled, y_test, n_repeats=10, random_state=42)
    importance_dict["Permutation"] = perm_importance.importances_mean

    # Mutual Information
    mi_scores = mutual_info_classif(X_train_scaled, y_train)
    importance_dict["Mutual Information"] = mi_scores

    return importance_dict

# Streamlit app
st.title('Heart Disease Feature Analysis')

# File upload (this line defines `uploaded_file`)
uploaded_file = st.file_uploader("Choose a CSV file", type="csv")

if uploaded_file is not None:
    data = pd.read_csv(uploaded_file)
    st.write("Data Preview:")
    st.write(data.head())

    # Select target variable
    target_col = st.selectbox("Select the target variable", data.columns)

    if st.button('Analyze'):
        X = data.drop(target_col, axis=1)
        y = data[target_col]

        # Ensure that `y` has continuous integer values for classification
        st.write("Original Target Values:", y.unique())  # Show original target values for debugging

        # Correlation Matrix
        st.subheader('Correlation Matrix')
        plot_correlation_matrix(data)

        # Feature Importance
        st.subheader('Feature Importance')
        importance_dict = calculate_feature_importance(X, y)

        # Create a DataFrame with all feature importances
        importance_df = pd.DataFrame(importance_dict, index=X.columns)
        st.write(importance_df)

else:
    st.write("Please upload a CSV file to begin the analysis.")