>>> import numpy as np
>>> z = np.zeros(9, dtype=np.int64)
>>> z
array([0, 0, 0, 0, 0, 0, 0, 0, 0], dtype=int64)
>>> z = z.reshape(3,3)
>>> z
array([[0, 0, 0],
[0, 0, 0],
[0, 0, 0]], dtype=int64)
>>> z[1,2] = 1
>>> z
array([[0, 0, 0],
[0, 0, 1],
[0, 0, 0]], dtype=int64)
>>> a = np.arange(10,49)
>>> a
array([10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26,
27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43,
44, 45, 46, 47, 48])
>>> a = np.flip(a)
>>> a
array([48, 47, 46, 45, 44, 43, 42, 41, 40, 39, 38, 37, 36, 35, 34, 33, 32,
31, 30, 29, 28, 27, 26, 25, 24, 23, 22, 21, 20, 19, 18, 17, 16, 15,
14, 13, 12, 11, 10])
>>> a[a.argmax()] = 0
>>> a
array([ 0, 47, 46, 45, 44, 43, 42, 41, 40, 39, 38, 37, 36, 35, 34, 33, 32,
31, 30, 29, 28, 27, 26, 25, 24, 23, 22, 21, 20, 19, 18, 17, 16, 15,
14, 13, 12, 11, 10])
>>> r = np.random.random((10,10))
>>> np.where(r==r.min()) # 最小值下标,第1个元素表示行索引,第2个元素表示列索引
(array([0], dtype=int64), array([0], dtype=int64))
>>> np.where(r==r.max()) # 最大值下标,第1个元素表示行索引,第2个元素表示列索引
(array([5], dtype=int64), array([6], dtype=int64))
>>> r.argmin(), r.argmax() # 也可以这样返回最小值、最大值的索引(展平为1维数组的索引)
(0, 56)
>>> r.min(), r.max() # 最小值、最大值
(0.011180968497130017, 0.9965216736718236)