In [1]:

    

import numpy as np


    

In [2]:

    

l = list(range(10))
print(l)


    

    




[0, 1, 2, 3, 4, 5, 6, 7, 8, 9]

In [3]:

    

print(l[4:8])


    

    




[4, 5, 6, 7]

In [4]:

    

print(l[-5:-2])


    

    




[5, 6, 7]

In [5]:

    

print(l[::-1])


    

    




[9, 8, 7, 6, 5, 4, 3, 2, 1, 0]

In [6]:

    

a = np.arange(10)
print(a)


    

    




[0 1 2 3 4 5 6 7 8 9]

In [7]:

    

print(a[4:8])


    

    




[4 5 6 7]

In [8]:

    

print(a[-5:-2])


    

    




[5 6 7]

In [9]:

    

print(a[::-1])


    

    




[9 8 7 6 5 4 3 2 1 0]

In [10]:

    

a[3:6] = 100
print(a)


    

    




[  0   1   2 100 100 100   6   7   8   9]

In [11]:

    

a[3:6] = [100, 200, 300]
print(a)


    

    




[  0   1   2 100 200 300   6   7   8   9]

In [12]:

    

# a[3:6] = [100, 200, 300, 400]
# ValueError: cannot copy sequence with size 4 to array axis with dimension 3


    

In [13]:

    

a = np.arange(10)
print(a)


    

    




[0 1 2 3 4 5 6 7 8 9]

In [14]:

    

print(a[2:8:2])


    

    




[2 4 6]

In [15]:

    

a[2:8:2] = 100
print(a)


    

    




[  0   1 100   3 100   5 100   7   8   9]

In [16]:

    

a[2:8:2] = [100, 200, 300]
print(a)


    

    




[  0   1 100   3 200   5 300   7   8   9]

In [17]:

    

a = np.arange(12).reshape((3, 4))
print(a)


    

    




[[ 0  1  2  3]
 [ 4  5  6  7]
 [ 8  9 10 11]]

In [18]:

    

print(a[1:, 1:3])


    

    




[[ 5  6]
 [ 9 10]]

In [19]:

    

print(a[1:, :])


    

    




[[ 4  5  6  7]
 [ 8  9 10 11]]

In [20]:

    

print(a[1:])


    

    




[[ 4  5  6  7]
 [ 8  9 10 11]]

In [21]:

    

print(a[1])


    

    




[4 5 6 7]

In [22]:

    

print(a[1].shape)


    

    




(4,)

In [23]:

    

print(a[1:2])


    

    




[[4 5 6 7]]

In [24]:

    

print(a[1:2].shape)


    

    




(1, 4)

In [25]:

    

print(a[:, 1:3])


    

    




[[ 1  2]
 [ 5  6]
 [ 9 10]]

In [26]:

    

print(a[:, 1])


    

    




[1 5 9]

In [27]:

    

print(a[:, 1].shape)


    

    




(3,)

In [28]:

    

print(a[:, 1:2])


    

    




[[1]
 [5]
 [9]]

In [29]:

    

print(a[:, 1:2].shape)


    

    




(3, 1)

In [30]:

    

a = np.arange(12).reshape((3, 4))
print(a)


    

    




[[ 0  1  2  3]
 [ 4  5  6  7]
 [ 8  9 10 11]]

In [31]:

    

print(a[1:, 1:3])


    

    




[[ 5  6]
 [ 9 10]]

In [32]:

    

a[1:, 1:3] = 100
print(a)


    

    




[[  0   1   2   3]
 [  4 100 100   7]
 [  8 100 100  11]]

In [33]:

    

a[1:, 1:3] = [100, 200]
print(a)


    

    




[[  0   1   2   3]
 [  4 100 200   7]
 [  8 100 200  11]]

In [34]:

    

a[1:, 1:3] = [[100, 200], [300, 400]]
print(a)


    

    




[[  0   1   2   3]
 [  4 100 200   7]
 [  8 300 400  11]]

In [35]:

    

a = np.arange(12).reshape((3, 4))
print(a)


    

    




[[ 0  1  2  3]
 [ 4  5  6  7]
 [ 8  9 10 11]]

In [36]:

    

print(a[1:, ::2])


    

    




[[ 4  6]
 [ 8 10]]

In [37]:

    

a[1:, ::2] = 100
print(a)


    

    




[[  0   1   2   3]
 [100   5 100   7]
 [100   9 100  11]]

In [38]:

    

a[1:, ::2] = [100, 200]
print(a)


    

    




[[  0   1   2   3]
 [100   5 200   7]
 [100   9 200  11]]

In [39]:

    

a[1:, ::2] = [[100, 200], [300, 400]]
print(a)


    

    




[[  0   1   2   3]
 [100   5 200   7]
 [300   9 400  11]]

In [40]:

    

a = np.arange(12).reshape((3, 4))
print(a)


    

    




[[ 0  1  2  3]
 [ 4  5  6  7]
 [ 8  9 10 11]]

In [41]:

    

a_slice = a[1:, 1:3]
print(a_slice)


    

    




[[ 5  6]
 [ 9 10]]

In [42]:

    

a_slice[0, 0] = 100
print(a_slice)


    

    




[[100   6]
 [  9  10]]

In [43]:

    

print(a)


    

    




[[  0   1   2   3]
 [  4 100   6   7]
 [  8   9  10  11]]

In [44]:

    

a = np.arange(12).reshape((3, 4))
print(a)


    

    




[[ 0  1  2  3]
 [ 4  5  6  7]
 [ 8  9 10 11]]

In [45]:

    

a_slice_copy = a[1:, 1:3].copy()
print(a_slice_copy)


    

    




[[ 5  6]
 [ 9 10]]

In [46]:

    

a_slice_copy[0, 0] = 100
print(a_slice_copy)


    

    




[[100   6]
 [  9  10]]

In [47]:

    

print(a)


    

    




[[ 0  1  2  3]
 [ 4  5  6  7]
 [ 8  9 10 11]]

In [48]:

    

a = np.arange(12).reshape((3, 4))
print(a)


    

    




[[ 0  1  2  3]
 [ 4  5  6  7]
 [ 8  9 10 11]]

In [49]:

    

print(a[[0, 2], 1:3])


    

    




[[ 1  2]
 [ 9 10]]

In [50]:

    

a[[0, 2], 1:3] = 100
print(a)


    

    




[[  0 100 100   3]
 [  4   5   6   7]
 [  8 100 100  11]]

In [51]:

    

a[[0, 2], 1:3] = [100, 200]
print(a)


    

    




[[  0 100 200   3]
 [  4   5   6   7]
 [  8 100 200  11]]

In [52]:

    

a[[0, 2], 1:3] = [[100, 200], [300, 400]]
print(a)


    

    




[[  0 100 200   3]
 [  4   5   6   7]
 [  8 300 400  11]]

In [53]:

    

a_subset = a[[0, 2], 1:3]
print(a_subset)


    

    




[[100 200]
 [300 400]]

In [54]:

    

a_subset[0, 0] = -1
print(a_subset)


    

    




[[ -1 200]
 [300 400]]

In [55]:

    

print(a)


    

    




[[  0 100 200   3]
 [  4   5   6   7]
 [  8 300 400  11]]