计算分组统计量

def solve():
    import numpy as np
    from sklearn.datasets import load_iris
    iris = load_iris()
    X = iris.data
    y = iris.target
    means = [np.mean(X[y == i, 0]) for i in range(3)]
    print(f'{means[0]:.2f},{means[1]:.2f},{means[2]:.2f}')