course_pages/week_6.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.linear_model import LogisticRegression
from sklearn.metrics import accuracy_score, classification_report, confusion_matrix
from sklearn.preprocessing import StandardScaler
import plotly.express as px
import plotly.graph_objects as go
from plotly.subplots import make_subplots
import scipy.stats as stats
from pathlib import Path
import statsmodels.api as sm
from ISLP import load_data
from ISLP.models import ModelSpec as MS, summarize

# Set up the style for all plots
plt.style.use('default')
sns.set_theme(style="whitegrid", palette="husl")

def load_smarket_data():
    """Load and prepare the Smarket data"""
    try:
        Smarket = load_data('Smarket')
        return Smarket
    except Exception as e:
        st.error(f"Error loading Smarket data: {str(e)}")
        return None

def create_confusion_matrix_plot(y_true, y_pred, title="Confusion Matrix"):
    """Create an interactive confusion matrix plot"""
    cm = confusion_matrix(y_true, y_pred)
    fig = go.Figure(data=go.Heatmap(
        z=cm,
        x=['Predicted Down', 'Predicted Up'],
        y=['Actual Down', 'Actual Up'],
        colorscale='RdBu',
        text=[[str(val) for val in row] for row in cm],
        texttemplate='%{text}',
        textfont={"size": 16}
    ))
    
    fig.update_layout(
        title=title,
        title_x=0.5,
        title_font_size=20,
        plot_bgcolor='rgb(30, 30, 30)',
        paper_bgcolor='rgb(30, 30, 30)',
        font=dict(color='white')
    )
    return fig

def create_correlation_heatmap(df):
    """Create a correlation heatmap using plotly"""
    corr = df.corr(numeric_only=True)
    
    fig = go.Figure(data=go.Heatmap(
        z=corr,
        x=corr.columns,
        y=corr.columns,
        colorscale='RdBu',
        zmin=-1, zmax=1,
        text=[[f'{val:.2f}' for val in row] for row in corr.values],
        texttemplate='%{text}',
        textfont={"size": 12}
    ))
    
    fig.update_layout(
        title='S&P 500 Returns Correlation Heatmap',
        title_x=0.5,
        title_font_size=20,
        plot_bgcolor='rgb(30, 30, 30)',
        paper_bgcolor='rgb(30, 30, 30)',
        font=dict(color='white')
    )
    return fig

def create_decision_boundary_plot(X, y, model):
    """Create an interactive decision boundary plot using plotly"""
    # Create a mesh grid
    x_min, x_max = X['Lag1'].min() - 1, X['Lag1'].max() + 1
    y_min, y_max = X['Lag2'].min() - 1, X['Lag2'].max() + 1
    xx, yy = np.meshgrid(np.arange(x_min, x_max, 0.01),
                        np.arange(y_min, y_max, 0.01))
    
    # Get predictions for the mesh grid
    Z = model.predict(np.c_[xx.ravel(), yy.ravel()])
    Z = Z.reshape(xx.shape)
    
    # Create the plot
    fig = go.Figure()
    
    # Add the decision boundary
    fig.add_trace(go.Contour(
        x=np.arange(x_min, x_max, 0.01),
        y=np.arange(y_min, y_max, 0.01),
        z=Z,
        colorscale='RdBu',
        showscale=False,
        opacity=0.5
    ))
    
    # Add the scatter points
    fig.add_trace(go.Scatter(
        x=X['Lag1'],
        y=X['Lag2'],
        mode='markers',
        marker=dict(
            color=y,
            colorscale='RdBu',
            size=8,
            line=dict(color='black', width=1)
        ),
        name='Data Points'
    ))
    
    # Update layout
    fig.update_layout(
        title='Logistic Regression Decision Boundary',
        xaxis_title='Lag1',
        yaxis_title='Lag2',
        plot_bgcolor='rgb(30, 30, 30)',
        paper_bgcolor='rgb(30, 30, 30)',
        font=dict(color='white'),
        showlegend=False
    )
    
    return fig

def show():
    st.title("Week 6: Logistic Regression and Stock Market Prediction")
    
    # Introduction Section
    st.header("Course Overview")
    st.write("""
    In this week, we'll use logistic regression to try predicting whether the stock market goes up or down.
    This is intentionally a challenging prediction problem that will teach us important lessons about:
    - When logistic regression works well and when it doesn't
    - How to interpret probabilities and coefficients
    - Why some prediction problems are inherently difficult
    - Proper model evaluation techniques
    """)
    
    # Learning Path
    st.subheader("Learning Path")
    st.write("""
    1. Understanding the Stock Market Data: S&P 500 returns and predictors
    2. Logistic Regression Fundamentals: From linear to logistic
    3. Model Training and Evaluation: Proper train-test splitting
    4. Interpreting Results: Coefficients and probabilities
    5. Model Assessment: Confusion matrices and metrics
    6. Real-world Applications: Challenges and limitations
    """)

    # Module 1: Understanding the Data
    st.header("Module 1: Understanding the Stock Market Data")
    st.write("""
    We'll examine the Smarket data, which consists of percentage returns for the S&P 500 stock index over 1,250 days,
    from the beginning of 2001 until the end of 2005. For each date, we have:
    - Percentage returns for each of the five previous trading days (Lag1 through Lag5)
    - Volume (number of shares traded on the previous day, in billions)
    - Today (percentage return on the date in question)
    - Direction (whether the market was Up or Down on this date)
    """)

    # Load and display data
    Smarket = load_smarket_data()
    if Smarket is not None:
        st.write("First few rows of the Smarket data:")
        st.dataframe(Smarket.head())
        
        # EDA Plots
        st.subheader("Exploratory Data Analysis")
        
        # Volume over time
        st.write("**Trading Volume Over Time**")
        fig_volume = go.Figure()
        fig_volume.add_trace(go.Scatter(
            x=Smarket.index,
            y=Smarket['Volume'],
            mode='lines',
            name='Volume'
        ))
        fig_volume.update_layout(
            title='Trading Volume Over Time',
            xaxis_title='Time',
            yaxis_title='Volume (billions of shares)',
            plot_bgcolor='rgb(30, 30, 30)',
            paper_bgcolor='rgb(30, 30, 30)',
            font=dict(color='white')
        )
        st.plotly_chart(fig_volume)
        
        # Returns distribution
        st.write("**Distribution of Returns**")
        
        # Add column selection
        selected_columns = st.multiselect(
            "Select columns to display",
            options=['Lag1', 'Lag2', 'Lag3', 'Lag4', 'Lag5', 'Today'],
            default=['Lag1', 'Lag2']
        )
        
        if selected_columns:
            fig_returns = go.Figure()
            for col in selected_columns:
                fig_returns.add_trace(go.Histogram(
                    x=Smarket[col],
                    name=col,
                    opacity=0.7,
                    nbinsx=50  # Adjust number of bins for better visualization
                ))
            
            # Add mean and std lines
            for col in selected_columns:
                mean_val = Smarket[col].mean()
                std_val = Smarket[col].std()
                fig_returns.add_vline(
                    x=mean_val,
                    line_dash="dash",
                    line_color="red",
                    annotation_text=f"{col} Mean: {mean_val:.2f}%",
                    annotation_position="top right",
                    annotation=dict(
                        textangle=-45,
                        font=dict(size=10)
                    )
                )
                fig_returns.add_vline(
                    x=mean_val + std_val,
                    line_dash="dot",
                    line_color="yellow",
                    annotation_text=f"{col} +1σ: {mean_val + std_val:.2f}%",
                    annotation_position="top right",
                    annotation=dict(
                        textangle=-45,
                        font=dict(size=10)
                    )
                )
                fig_returns.add_vline(
                    x=mean_val - std_val,
                    line_dash="dot",
                    line_color="yellow",
                    annotation_text=f"{col} -1σ: {mean_val - std_val:.2f}%",
                    annotation_position="top right",
                    annotation=dict(
                        textangle=-45,
                        font=dict(size=10)
                    )
                )
            
            fig_returns.update_layout(
                title='Distribution of Returns',
                xaxis_title='Return (%)',
                yaxis_title='Frequency',
                barmode='overlay',
                plot_bgcolor='rgb(30, 30, 30)',
                paper_bgcolor='rgb(30, 30, 30)',
                font=dict(color='white'),
                showlegend=True,
                legend=dict(
                    yanchor="top",
                    y=0.99,
                    xanchor="left",
                    x=0.01
                )
            )
            
            # Add summary statistics
            st.write("**Summary Statistics**")
            summary_stats = Smarket[selected_columns].describe()
            st.dataframe(summary_stats.style.format('{:.2f}'))
            
            st.plotly_chart(fig_returns)
            
            # Add interpretation
            st.write("""
            **Interpretation:**
            - The dashed red line shows the mean return for each selected period
            - The dotted yellow lines show one standard deviation above and below the mean
            - The overlap of distributions helps identify similarities in return patterns
            - Wider distributions indicate higher volatility
            """)

        # Returns over time
        st.write("**Returns Over Time**")
        fig_returns_time = go.Figure()
        fig_returns_time.add_trace(go.Scatter(
            x=Smarket.index,
            y=Smarket['Today'],
            mode='lines',
            name='Today\'s Return'
        ))
        fig_returns_time.update_layout(
            title='Daily Returns Over Time',
            xaxis_title='Time',
            yaxis_title='Return (%)',
            plot_bgcolor='rgb(30, 30, 30)',
            paper_bgcolor='rgb(30, 30, 30)',
            font=dict(color='white')
        )
        st.plotly_chart(fig_returns_time)
        
        # Direction distribution
        st.write("**Market Direction Distribution**")
        direction_counts = Smarket['Direction'].value_counts()
        fig_direction = go.Figure(data=[go.Pie(
            labels=direction_counts.index,
            values=direction_counts.values,
            hole=.3
        )])
        fig_direction.update_layout(
            title='Distribution of Market Direction',
            plot_bgcolor='rgb(30, 30, 30)',
            paper_bgcolor='rgb(30, 30, 30)',
            font=dict(color='white')
        )
        st.plotly_chart(fig_direction)
        
        # Show correlation heatmap
        st.write("**Correlation Analysis**")
        st.plotly_chart(create_correlation_heatmap(Smarket))
        
        st.write("""
        Key observations from the exploratory analysis:
        
        1. **Trading Volume**:
           - Shows an increasing trend over time
           - Higher volatility in recent years
           - Some periods of unusually high volume
        
        2. **Returns Distribution**:
           - Approximately normal distribution
           - Most returns are close to zero
           - Some extreme values (outliers)
        
        3. **Market Direction**:
           - Relatively balanced between Up and Down days
           - Slight bias towards Up days
        
        4. **Correlations**:
           - Low correlation between lagged returns
           - Strong correlation between Year and Volume
           - Today's return shows little correlation with past returns
        """)

    # Module 2: Logistic Regression Implementation
    st.header("Module 2: Logistic Regression Implementation")
    st.write("""
    We'll fit a logistic regression model to predict Direction using Lag1 through Lag5 and Volume.
    The model will help us understand if we can predict market movements based on recent trading patterns.
    """)

    if Smarket is not None:
        # Prepare data for logistic regression
        allvars = Smarket.columns.drop(['Today', 'Direction', 'Year'])
        design = MS(allvars)
        X = design.fit_transform(Smarket)
        y = Smarket.Direction == 'Up'
        
        # Fit the model
        glm = sm.GLM(y, X, family=sm.families.Binomial())
        results = glm.fit()
        
        # Display model summary
        st.write("Model Summary:")
        st.write(summarize(results))
        
        # Show coefficients
        st.write("Model Coefficients:")
        coef_df = pd.DataFrame({
            'Feature': allvars,
            'Coefficient': results.params[1:],  # Skip the intercept
            'P-value': results.pvalues[1:]  # Skip the intercept
        })
        st.write(coef_df)

    # Module 3: Model Evaluation
    st.header("Module 3: Model Evaluation")
    st.write("""
    We'll evaluate our model using proper train-test splitting, focusing on predicting 2005 data using models trained on 2001-2004 data.
    This gives us a more realistic assessment of model performance.
    """)

    if Smarket is not None:
        # Split data by year
        train = (Smarket.Year < 2005)
        X_train, X_test = X.loc[train], X.loc[~train]
        y_train, y_test = y.loc[train], y.loc[~train]
        
        # Fit model on training data
        glm_train = sm.GLM(y_train, X_train, family=sm.families.Binomial())
        results = glm_train.fit()
        
        # Make predictions
        probs = results.predict(exog=X_test)
        labels = np.array(['Down']*len(probs))
        labels[probs>0.5] = 'Up'
        
        # Show confusion matrix
        st.plotly_chart(create_confusion_matrix_plot(Smarket.Direction[~train], labels))
        
        # Calculate and display accuracy
        accuracy = np.mean(labels == Smarket.Direction[~train])
        st.write(f"Test Accuracy: {accuracy:.2%}")

    # Module 4: Decision Boundary Visualization
    st.header("Module 4: Decision Boundary Visualization")
    st.write("""
    Let's visualize how our logistic regression model separates the market movements using Lag1 and Lag2 as predictors.
    The decision boundary shows how the model classifies different combinations of previous day returns.
    """)

    if Smarket is not None:
        # Prepare data for decision boundary plot
        X_plot = Smarket[['Lag1', 'Lag2']]
        y_plot = (Smarket['Direction'] == 'Up').astype(int)
        
        # Fit a simple logistic regression model for visualization
        log_reg = LogisticRegression()
        log_reg.fit(X_plot, y_plot)
        
        # Create and display the decision boundary plot
        st.plotly_chart(create_decision_boundary_plot(X_plot, y_plot, log_reg))
        
        st.write("""
        The decision boundary plot shows:
        - Blue regions indicate where the model predicts the market will go down
        - Red regions indicate where the model predicts the market will go up
        - The boundary between these regions represents where the model is uncertain
        - The scatter points show actual market movements, colored by their true direction
        """)

    # Module 5: Interpreting Logistic Regression Results
    st.header("Module 5: Interpreting Logistic Regression Results")
    
    st.subheader("Understanding the Coefficients")
    st.write("""
    In logistic regression, coefficients tell us about the relationship between predictors and the probability of the outcome.
    Let's break down how to interpret them:
    
    1. **Coefficient Sign**:
       - Positive coefficients increase the probability of the outcome (market going up)
       - Negative coefficients decrease the probability of the outcome (market going down)
    
    2. **Coefficient Magnitude**:
       - Larger absolute values indicate stronger effects
       - The effect is non-linear due to the logistic function
    """)

    # Add visualization comparing linear and logistic regression
    st.write("**Linear vs Logistic Regression**")
    
    # Create sample data
    x = np.linspace(-5, 5, 100)
    y_linear = 0.5 * x + 0.5  # Linear regression
    y_logistic = 1 / (1 + np.exp(-(2 * x)))  # Logistic regression with steeper slope
    
    # Create the comparison plot
    fig_comparison = go.Figure()
    
    # Add linear regression line
    fig_comparison.add_trace(go.Scatter(
        x=x,
        y=y_linear,
        mode='lines',
        name='Linear Regression',
        line=dict(color='blue', width=2)
    ))
    
    # Add logistic regression curve
    fig_comparison.add_trace(go.Scatter(
        x=x,
        y=y_logistic,
        mode='lines',
        name='Logistic Regression',
        line=dict(color='red', width=2)
    ))
    
    # Add some sample points with more extreme separation
    np.random.seed(42)
    x_samples = np.random.normal(0, 1, 50)
    # Make the separation more clear
    y_samples = (x_samples > 0.5).astype(int)  # Changed threshold to 0.5 for clearer separation
    
    fig_comparison.add_trace(go.Scatter(
        x=x_samples,
        y=y_samples,
        mode='markers',
        name='Sample Data',
        marker=dict(
            color=['red' if y == 0 else 'green' for y in y_samples],
            size=8,
            symbol='circle'
        )
    ))
    
    # Update layout
    fig_comparison.update_layout(
        title='Linear vs Logistic Regression',
        xaxis_title='Input Feature (X)',
        yaxis_title='Output',
        plot_bgcolor='rgb(30, 30, 30)',
        paper_bgcolor='rgb(30, 30, 30)',
        font=dict(color='white'),
        showlegend=True,
        legend=dict(
            yanchor="top",
            y=0.99,
            xanchor="left",
            x=0.01
        ),
        yaxis=dict(
            range=[-0.1, 1.1]  # Extend y-axis range slightly
        )
    )
    
    # Add annotations
    fig_comparison.add_annotation(
        x=2, y=0.8,
        text="Linear Regression<br>predicts continuous values",
        showarrow=True,
        arrowhead=1,
        ax=50, ay=-30,
        font=dict(color='white', size=10)
    )
    
    fig_comparison.add_annotation(
        x=2, y=0.3,
        text="Logistic Regression<br>predicts probabilities<br>(S-shaped curve)",
        showarrow=True,
        arrowhead=1,
        ax=50, ay=30,
        font=dict(color='white', size=10)
    )
    
    # Add decision boundary annotation
    fig_comparison.add_annotation(
        x=0, y=0.5,
        text="Decision Boundary<br>(p = 0.5)",
        showarrow=True,
        arrowhead=1,
        ax=0, ay=-40,
        font=dict(color='white', size=10)
    )
    
    st.plotly_chart(fig_comparison)
    
    st.write("""
    **Key Differences:**
    
    1. **Output Range**:
       - Linear Regression: Can predict any value (-∞ to +∞)
       - Logistic Regression: Predicts probabilities (0 to 1)
    
    2. **Function Shape**:
       - Linear Regression: Straight line
       - Logistic Regression: S-shaped curve (sigmoid)
       - The sigmoid function creates a sharp transition around the decision boundary
    
    3. **Use Case**:
       - Linear Regression: Predicting continuous values
       - Logistic Regression: Predicting binary outcomes (Up/Down)
    
    4. **Interpretation**:
       - Linear Regression: Direct relationship between X and Y
       - Logistic Regression: Non-linear relationship between X and probability of Y
       - Small changes in X can lead to large changes in probability near the decision boundary
    """)

    if Smarket is not None:
        # Calculate and display coefficients
        st.subheader("Example: Interpreting Our Model's Coefficients")
        
        # Get coefficients from the model
        coef_results = pd.DataFrame({
            'Feature': allvars,
            'Coefficient': results.params[1:],
            'P-value': results.pvalues[1:]
        })
        
        st.write("Coefficient Analysis:")
        st.dataframe(coef_results.style.format({
            'Coefficient': '{:.4f}',
            'P-value': '{:.4f}'
        }))
        
        st.write("""
        Let's interpret some examples from our model:
        
        1. **Lag1 Coefficient**:
           - A positive coefficient means that higher values of Lag1 are associated with higher probability of the market going up
           - The magnitude tells us how strong this relationship is
        
        2. **Volume Coefficient**:
           - A positive coefficient suggests that higher trading volume is associated with higher probability of upward market movement
           - The size of the coefficient indicates the strength of this relationship
        """)

    st.subheader("Understanding Model Performance")
    st.write("""
    Our model's performance metrics tell us important information:
    
    1. **Accuracy**:
       - The proportion of correct predictions
       - In our case, around 52% accuracy on the test set
       - This is slightly better than random guessing (50%)
    
    2. **Confusion Matrix**:
       The confusion matrix is a 2x2 table that shows:
       
       - **True Positives (TP)**: 
         - Correctly predicted market going up
         - These are the cases where we predicted 'Up' and the market actually went up
       
       - **False Positives (FP)**:
         - Incorrectly predicted market going up
         - These are the cases where we predicted 'Up' but the market actually went down
         - Also known as Type I errors
       
       - **True Negatives (TN)**:
         - Correctly predicted market going down
         - These are the cases where we predicted 'Down' and the market actually went down
       
       - **False Negatives (FN)**:
         - Incorrectly predicted market going down
         - These are the cases where we predicted 'Down' but the market actually went up
         - Also known as Type II errors
       
       From these values, we can calculate important metrics:
       - **Precision** = TP / (TP + FP): How many of our 'Up' predictions were correct
       - **Recall** = TP / (TP + FN): How many of the actual 'Up' days did we catch
       - **F1 Score** = 2 * (Precision * Recall) / (Precision + Recall): Balanced measure of precision and recall
       - **Accuracy** = (TP + TN) / (TP + TN + FP + FN): Overall correct predictions
    
    3. **P-values**:
       - Indicate statistical significance of each predictor
       - P-value < 0.05 suggests the predictor is significant
       - In our case, most predictors are not statistically significant
    """)

    st.subheader("Practical Implications")
    st.write("""
    What does this mean for real-world trading?
    
    1. **Model Limitations**:
       - The model's accuracy is only slightly better than random guessing
       - This suggests that predicting market direction is inherently difficult
       - Past returns alone are not reliable predictors
    
    2. **Risk Management**:
       - Even with a model, trading decisions should include:
         - Stop-loss orders
         - Position sizing
         - Diversification
         - Risk tolerance considerations
    
    3. **Model Improvement**:
       - Consider adding more features:
         - Technical indicators
         - Market sentiment
         - Economic indicators
       - Use more sophisticated models:
         - Ensemble methods
         - Deep learning
         - Time series models
    """)

    st.subheader("Example: Making a Prediction")
    st.write("""
    Let's walk through an example of making a prediction:
    
    1. **Input Data**:
       - Lag1 = 1.2% (yesterday's return)
       - Lag2 = -0.8% (day before yesterday's return)
       - Volume = 1.1 billion shares
    
    2. **Calculate Probability**:
       - Use the logistic function: P(Y=1) = 1 / (1 + e^(-z))
       - where z = β₀ + β₁(Lag1) + β₂(Lag2) + ... + β₆(Volume)
    
    3. **Interpret Result**:
       - If P(Y=1) > 0.5, predict market will go up
       - If P(Y=1) < 0.5, predict market will go down
       - The probability itself tells us about confidence
    """)

    if Smarket is not None:
        # Example prediction
        st.write("**Interactive Example:**")
        col1, col2, col3 = st.columns(3)
        
        with col1:
            lag1 = st.number_input("Lag1 (%)", value=1.2, step=0.1)
        with col2:
            lag2 = st.number_input("Lag2 (%)", value=-0.8, step=0.1)
        with col3:
            volume = st.number_input("Volume (billions)", value=1.1, step=0.1)
        
        # Make prediction
        X_example = pd.DataFrame({
            'Lag1': [lag1],
            'Lag2': [lag2],
            'Lag3': [0],
            'Lag4': [0],
            'Lag5': [0],
            'Volume': [volume]
        })
        
        # Transform using the same design matrix
        X_example = design.transform(X_example)
        prob = results.predict(X_example)[0]
        
        st.write(f"""
        **Prediction Results:**
        - Probability of market going up: {prob:.2%}
        - Predicted direction: {'Up' if prob > 0.5 else 'Down'}
        - Confidence level: {abs(prob - 0.5)*2:.2%}
        """)

    # Practice Exercises
    st.header("Practice Exercises")
    
    with st.expander("Exercise 1: Implementing Logistic Regression with Lag1 and Lag2"):
        st.write("""
        1. Implement a logistic regression model using only Lag1 and Lag2
        2. Compare its performance with the full model
        3. Analyze the coefficients and their significance
        4. Visualize the results
        """)
        
        st.code("""
        # Solution
        model = MS(['Lag1', 'Lag2']).fit(Smarket)
        X = model.transform(Smarket)
        X_train, X_test = X.loc[train], X.loc[~train]
        
        glm_train = sm.GLM(y_train, X_train, family=sm.families.Binomial())
        results = glm_train.fit()
        
        probs = results.predict(exog=X_test)
        labels = np.array(['Down']*len(probs))
        labels[probs>0.5] = 'Up'
        
        # Evaluate performance
        accuracy = np.mean(labels == Smarket.Direction[~train])
        print(f"Test Accuracy: {accuracy:.2%}")
        """)
    
    with st.expander("Exercise 2: Making Predictions for New Data"):
        st.write("""
        1. Create a function to make predictions for new market conditions
        2. Test the model with specific Lag1 and Lag2 values
        3. Interpret the predicted probabilities
        4. Discuss the model's limitations
        """)
        
        st.code("""
        # Solution
        def predict_market_direction(lag1, lag2):
            newdata = pd.DataFrame({'Lag1': [lag1], 'Lag2': [lag2]})
            newX = model.transform(newdata)
            prob = results.predict(newX)[0]
            return prob
        
        # Example predictions
        prob1 = predict_market_direction(1.2, 1.1)
        prob2 = predict_market_direction(1.5, -0.8)
        
        print(f"Probability of market going up for Lag1=1.2, Lag2=1.1: {prob1:.2%}")
        print(f"Probability of market going up for Lag1=1.5, Lag2=-0.8: {prob2:.2%}")
        """)

    # Weekly Assignment
    username = st.session_state.get("username", "Student")
    st.header(f"{username}'s Weekly Assignment")
    
    if username == "manxiii":
        st.markdown("""
        Hello **manxiii**, here is your Assignment 6: Stock Market Prediction with Logistic Regression.
        1. Implement a logistic regression model using Lag1 and Lag2
        2. Compare its performance with the full model
        3. Analyze the coefficients and their significance
        4. Create visualizations to support your findings
        5. Write a brief report on why stock market prediction is challenging

        **Due Date:** End of Week 6
        """)
    elif username == "zhu":
        st.markdown("""
        Hello **zhu**, here is your Assignment 6: Stock Market Prediction with Logistic Regression.
        """)
    elif username == "WK":
        st.markdown("""
        Hello **WK**, here is your Assignment 6: Stock Market Prediction with Logistic Regression.
        """)
    else:
        st.markdown(f"""
        Hello **{username}**, here is your Assignment 6: Stock Market Prediction with Logistic Regression.
        Please contact the instructor for your specific assignment.
        """)