自相关系数ACF

def solve():
    import pandas as pd
    import matplotlib.pyplot as plt
    from statsmodels.graphics.tsaplots import plot_acf
    url = '____'
    df = pd.read_csv(____)
    y = df['____']
    for lag in [____,____,____]:
        acf = y.corr(y.shift(____))
        print(____)
    plt.figure(figsize=(____,____))
    plot_acf(____)
    plt.title(____); plt.tight_layout(); plt.show()