import numpy as np
x = np.array([2, 4, 7, 9, 20])
print('x的形状:', x.shape)  # x的形状: (5,)
print('x的值:', x)          # x的值: [ 2  4  7  9 20]

x_new1 = x[np.newaxis, :]
#  (5,)  -----》  (1, 5)
print('x_new1的形状:', x_new1.shape)  # x_new1的形状: (1, 5)
print('x_new1的值:', x_new1)          # x_new1的值: [[ 2  4  7  9 20]]

x_new2 = x[:, np.newaxis]
#  (5,)  -----》  (5, 1)
print('x_new2的形状:', x_new2.shape)  # x_new2的形状: (5, 1)
print('x_new2的值:', x_new2)          #
# x_new2的值: [[ 2]
#  [ 4]
#  [ 7]
#  [ 9]
#  [20]]