np.argmax()

>>> a = np.arange(6).reshape(2,3)
>>> a
array([[0, 1, 2],
       [3, 4, 5]])
>>> np.argmax(a)
5
>>> np.argmax(a, axis=0)#0代表列
array([1, 1, 1])
>>> np.argmax(a, axis=1)#1代表行
array([2, 2])