给numpy.array增加维度的超简单方法

import numpy as np 
a = np.array([1, 2, 3])
print(a) 

print(a[None])

print(a[:,None])

import numpy as np
a = np.array([[1,2],[3,4]])
a.shape
print(a)
>>>
"""
(2L, 2L)
[[1 2]
 [3 4]]
"""
# 如果需要在数组上增加维度,输入需要增添维度的轴即可，注意index从零还是
a_add_dimension = np.expand_dims(a,axis=0)
a_add_dimension.shape
>>> (1L, 2L, 2L)

a_add_dimension2 = np.expand_dims(a,axis=-1)
a_add_dimension2.shape
>>> (2L, 2L, 1L)

a_add_dimension3 = np.expand_dims(a,axis=1)
a_add_dimension3.shape
>>> (2L, 1L, 2L)

b = np.array([[[[5],[6]],[[7],[8]]]])
b.shape
print(b)
>>>
"""
(1L, 2L, 2L, 1L)
array([[[[5],
         [6]],

        [[7],
         [8]]]])
"""
b_squeeze = b.squeeze()
b_squeeze.shape
>>>(2L, 2L)   #默认压缩所有为1的维度

b_squeeze0 = b.squeeze(axis=0)   #调用array实例的方法
b_squeeze0.shape
>>>(2L, 2L, 1L)

b_squeeze3 = np.squeeze(b, axis=3)   #调用numpy的方法
b_squeeze3.shape
>>>(1L, 2L, 2L)