In [1]:

    

import numpy as np


    

In [2]:

    

print(np.newaxis is None)


    

    




True

In [3]:

    

a = np.arange(6).reshape(2, 3)
print(a)


    

    




[[0 1 2]
 [3 4 5]]

In [4]:

    

print(a.shape)


    

    




(2, 3)

In [5]:

    

print(a[:, :, np.newaxis])


    

    




[[[0]
  [1]
  [2]]

 [[3]
  [4]
  [5]]]

In [6]:

    

print(a[:, :, np.newaxis].shape)


    

    




(2, 3, 1)

In [7]:

    

print(a[:, np.newaxis, :])


    

    




[[[0 1 2]]

 [[3 4 5]]]

In [8]:

    

print(a[:, np.newaxis, :].shape)


    

    




(2, 1, 3)

In [9]:

    

print(a[np.newaxis, :, :])


    

    




[[[0 1 2]
  [3 4 5]]]

In [10]:

    

print(a[np.newaxis, :, :].shape)


    

    




(1, 2, 3)

In [11]:

    

print(a[:, np.newaxis])


    

    




[[[0 1 2]]

 [[3 4 5]]]

In [12]:

    

print(a[:, np.newaxis].shape)


    

    




(2, 1, 3)

In [13]:

    

print(a[np.newaxis])


    

    




[[[0 1 2]
  [3 4 5]]]

In [14]:

    

print(a[np.newaxis].shape)


    

    




(1, 2, 3)

In [15]:

    

print(a[..., np.newaxis])


    

    




[[[0]
  [1]
  [2]]

 [[3]
  [4]
  [5]]]

In [16]:

    

print(a[..., np.newaxis].shape)


    

    




(2, 3, 1)

In [17]:

    

print(a[np.newaxis, :, np.newaxis, :, np.newaxis])


    

    




[[[[[0]
    [1]
    [2]]]


  [[[3]
    [4]
    [5]]]]]

In [18]:

    

print(a[np.newaxis, :, np.newaxis, :, np.newaxis].shape)


    

    




(1, 2, 1, 3, 1)

In [19]:

    

a_newaxis = a[:, :, np.newaxis]


    

In [20]:

    

print(np.shares_memory(a, a_newaxis))


    

    




True

In [21]:

    

a = np.zeros(27, dtype=np.int).reshape(3, 3, 3)
print(a)


    

    




[[[0 0 0]
  [0 0 0]
  [0 0 0]]

 [[0 0 0]
  [0 0 0]
  [0 0 0]]

 [[0 0 0]
  [0 0 0]
  [0 0 0]]]

In [22]:

    

print(a.shape)


    

    




(3, 3, 3)

In [23]:

    

b = np.arange(9).reshape(3, 3)
print(b)


    

    




[[0 1 2]
 [3 4 5]
 [6 7 8]]

In [24]:

    

print(b.shape)


    

    




(3, 3)

In [25]:

    

print(a + b)


    

    




[[[0 1 2]
  [3 4 5]
  [6 7 8]]

 [[0 1 2]
  [3 4 5]
  [6 7 8]]

 [[0 1 2]
  [3 4 5]
  [6 7 8]]]

In [26]:

    

print(b[np.newaxis, :, :].shape)


    

    




(1, 3, 3)

In [27]:

    

print(a + b[np.newaxis, :, :])


    

    




[[[0 1 2]
  [3 4 5]
  [6 7 8]]

 [[0 1 2]
  [3 4 5]
  [6 7 8]]

 [[0 1 2]
  [3 4 5]
  [6 7 8]]]

In [28]:

    

print(b[:, np.newaxis, :].shape)


    

    




(3, 1, 3)

In [29]:

    

print(a + b[:, np.newaxis, :])


    

    




[[[0 1 2]
  [0 1 2]
  [0 1 2]]

 [[3 4 5]
  [3 4 5]
  [3 4 5]]

 [[6 7 8]
  [6 7 8]
  [6 7 8]]]

In [30]:

    

print(b[:, :, np.newaxis].shape)


    

    




(3, 3, 1)

In [31]:

    

print(a + b[:, :, np.newaxis])


    

    




[[[0 0 0]
  [1 1 1]
  [2 2 2]]

 [[3 3 3]
  [4 4 4]
  [5 5 5]]

 [[6 6 6]
  [7 7 7]
  [8 8 8]]]

In [32]:

    

a = np.arange(6).reshape(2, 3)
print(a)


    

    




[[0 1 2]
 [3 4 5]]

In [33]:

    

print(a.shape)


    

    




(2, 3)

In [34]:

    

print(a[np.newaxis])


    

    




[[[0 1 2]
  [3 4 5]]]

In [35]:

    

print(a[np.newaxis].shape)


    

    




(1, 2, 3)

In [36]:

    

print(np.expand_dims(a, 0))


    

    




[[[0 1 2]
  [3 4 5]]]

In [37]:

    

print(np.expand_dims(a, 0).shape)


    

    




(1, 2, 3)

In [38]:

    

print(a.reshape(1, 2, 3))


    

    




[[[0 1 2]
  [3 4 5]]]

In [39]:

    

print(a.reshape(1, 2, 3).shape)


    

    




(1, 2, 3)

In [40]:

    

print(a.reshape(1, *a.shape))


    

    




[[[0 1 2]
  [3 4 5]]]

In [41]:

    

print(a.reshape(1, *a.shape).shape)


    

    




(1, 2, 3)