1.创建一个边界值为1而内部都是0的数组,图例如下:
[提示:]解此题可以先把所有值都设置为1,这是大正方形;其次,把边界除外小正方形全部设置为0。
本题用到numpy的切片原理。多维数组同样遵循x[start:stop:step]的原理。
[1. 1. 1. 1. 1. 1. 1. 1. 1. 1.]
[1. 0. 0. 0. 0. 0. 0. 0. 0. 1.]
[1. 0. 0. 0. 0. 0. 0. 0. 0. 1.]
[1. 0. 0. 0. 0. 0. 0. 0. 0. 1.]
[1. 0. 0. 0. 0. 0. 0. 0. 0. 1.]
[1. 0. 0. 0. 0. 0. 0. 0. 0. 1.]
[1. 0. 0. 0. 0. 0. 0. 0. 0. 1.]
[1. 0. 0. 0. 0. 0. 0. 0. 0. 1.]
[1. 0. 0. 0. 0. 0. 0. 0. 0. 1.]
[1. 1. 1. 1. 1. 1. 1. 1. 1. 1.]
import numpy as np a = np.ones((10, 10)) for i in range(1, 9): for j in range(1, 9): a[i][j] = 0 print(a)
import numpy as np A=np.ones((10,10)) A[1:-1,1:-1] = 0 print(A)
2.在数组主对角线上创建一个值为1,2,3,4的5x5矩阵,图例如下:
[1 0 0 0]
[0 2 0 0]
[0 0 3 0]
[0 0 0 4]
import numpy as np a = np.zeros((5, 5)) for i in range(0, 5): a[i][i] = i+1 print(a)
3.数组归一化操作
生成一个随机的5*5矩阵,找出最大值和最小值,然后把最大值和最小值分别用1和0表示,其他值则介于在0和1中间
import numpy as np a = np.random.rand(5, 5) amax, amin = np.max(a), np.min(a) a = a-amin a = a/(amax-amin) print(a)