GPA多维度对比（多子图）

def solve():
    import pandas as pd
    import matplotlib.pyplot as plt
    import numpy as np
    
    url = 'https://liangdaima.com/static/data/wooldridge/gpa1.csv'
    df = pd.read_csv(url)
    
    fig, axes = plt.subplots(2, 2, figsize=(14, 10))
    axes[0,0].hist(df['colGPA'], bins=15, color='gold', edgecolor='black', alpha=0.7)
    axes[0,0].set_title('大学GPA分布')
    if 'hsGPA' in df.columns:
        axes[0,1].scatter(df['hsGPA'], df['colGPA'], alpha=0.5, color='green')
        axes[0,1].set_title('高中GPA vs 大学GPA')
    axes[1,0].hist(df['ACT'], bins=12, color='purple', edgecolor='black', alpha=0.7)
    axes[1,0].set_title('ACT分数分布')
    axes[1,1].boxplot([df['colGPA']], labels=['大学GPA'])
    axes[1,1].set_title('GPA箱线图')
    for ax in axes.flat:
        ax.grid(alpha=0.3)
    plt.tight_layout()
    plt.show()
    return "可视化代码执行完成"