34 slicing for two dimentional array

In [1]:

import numpy as np

In [7]:

a1 = np.arange(5,25)

In [8]:

a1

Out[8]:

array([ 5,  6,  7,  8,  9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21,
       22, 23, 24])

In [9]:

a1

Out[9]:

array([ 5,  6,  7,  8,  9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21,
       22, 23, 24])

In [10]:

a1[1]

Out[10]:

6

In [11]:

a1[:]

Out[11]:

array([ 5,  6,  7,  8,  9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21,
       22, 23, 24])

In [13]:

a1[0:5]

Out[13]:

array([5, 6, 7, 8, 9])

In [14]:

a1[:6]

Out[14]:

array([ 5,  6,  7,  8,  9, 10])

In [15]:

a1[4:]

Out[15]:

array([ 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24])

In [16]:

a1[:-1]

Out[16]:

array([ 5,  6,  7,  8,  9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21,
       22, 23])

In [17]:

a1[:-5]

Out[17]:

array([ 5,  6,  7,  8,  9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19])

In [18]:

a1[1:5]=55

In [19]:

a1

Out[19]:

array([ 5, 55, 55, 55, 55, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21,
       22, 23, 24])

In [20]:

a1[]=55

  File "<ipython-input-20-42de2d9c776d>", line 1
    a1[]=55
       ^
SyntaxError: invalid syntax

In [21]:

a1[:]=55

In [22]:

a1

Out[22]:

array([55, 55, 55, 55, 55, 55, 55, 55, 55, 55, 55, 55, 55, 55, 55, 55, 55,
       55, 55, 55])

In [23]:

a1 = np.arange(5,25)

In [24]:

a1

Out[24]:

array([ 5,  6,  7,  8,  9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21,
       22, 23, 24])

In [25]:

a2=a1[0:10]

In [26]:

a2

Out[26]:

array([ 5,  6,  7,  8,  9, 10, 11, 12, 13, 14])

In [27]:

a2[:5]=55

In [28]:

a2

Out[28]:

array([55, 55, 55, 55, 55, 10, 11, 12, 13, 14])

In [29]:

a1

Out[29]:

array([55, 55, 55, 55, 55, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21,
       22, 23, 24])

In [30]:

a1 = np.arange(5,25)

In [31]:

a3=a1.copy()

In [32]:

a3

Out[32]:

array([ 5,  6,  7,  8,  9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21,
       22, 23, 24])

In [33]:

a3[:4]=20

In [34]:

a3

Out[34]:

array([20, 20, 20, 20,  9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21,
       22, 23, 24])

In [35]:

a1

Out[35]:

array([ 5,  6,  7,  8,  9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21,
       22, 23, 24])

In [38]:

a4=a1[1:6].copy()

In [39]:

a4

Out[39]:

array([ 6,  7,  8,  9, 10])

In [41]:

z1= np.array(([5,10,15],[20,25,30],[35,40,45]))

In [42]:

z1

Out[42]:

array([[ 5, 10, 15],
       [20, 25, 30],
       [35, 40, 45]])

In [43]:

atwo=np.array(([2,6,7],[3,8,0],[99,33,10]))

In [44]:

atwo

Out[44]:

array([[ 2,  6,  7],
       [ 3,  8,  0],
       [99, 33, 10]])

In [50]:

atwo[1][0]

Out[50]:

3

In [51]:

atwo[1,0]

Out[51]:

3

In [52]:

atwo[,0]

  File "<ipython-input-52-41f804cb2da2>", line 1
    atwo[,0]
         ^
SyntaxError: invalid syntax

In [53]:

atwo[:,2]

Out[53]:

array([ 7,  0, 10])

In [54]:

atwo[:,0]

Out[54]:

array([ 2,  3, 99])

In [55]:

atwo

Out[55]:

array([[ 2,  6,  7],
       [ 3,  8,  0],
       [99, 33, 10]])

In [58]:

b=atwo[:2,1:]

In [59]:

b

Out[59]:

array([[6, 7],
       [8, 0]])

In [64]:

atwo[:1,2:]

Out[64]:

array([[7]])

In [65]:

b=atwo[:2]

In [66]:

atwo[:2]

Out[66]:

array([[2, 6, 7],
       [3, 8, 0]])

In [70]:

atwo[:2,:2]

Out[70]:

array([[2, 6],
       [3, 8]])