np.mean() 中的 axis =0 是指對列進行求均值， axis=1是指對行求均值

a = [1,2,3]
...: b = [4,5,6]
...: e = np.array(list(zip(a,b)))
...: print(e)
...: print(np.mean(e,axis=0))
...: print(np.mean(e, axis=1))
...:
[[1 4]
[2 5]
[3 6]]

[2. 5.]
[2.5 3.5 4.5]