睡眠时间分布（Matplotlib基础）

def solve():
    import pandas as pd
    import matplotlib.pyplot as plt
    import numpy as np
    
    url = 'https://liangdaima.com/static/data/wooldridge/sleep75.csv'
    df = pd.read_csv(url)
    
    plt.figure(figsize=(10,6))
    plt.hist(df['sleep'], bins=20, color='indigo', edgecolor='black', alpha=0.7)
    plt.axvline(df['sleep'].mean(), color='red', linestyle='--', linewidth=2, label=f'均值: {df["sleep"].mean():.1f}')
    plt.title('睡眠时间分布', fontsize=14)
    plt.xlabel('每周睡眠时间（分钟）', fontsize=12)
    plt.ylabel('频数', fontsize=12)
    plt.legend()
    plt.grid(axis='y', alpha=0.3)
    plt.tight_layout()
    plt.show()
    return "可视化代码执行完成"