numpy学习笔记

In [4]:

 

 

 

 

 

 

 

 

 

 

import numpy as np

my_list = [1,2,3]

x = np.array(my_list)

​

print('列表',my_list)

print('Array:',x)

 

 

×

 

 

 

列表 [1, 2, 3]
Array: [1 2 3]

. . .

In [5]:

 

 

 

 

 

 

 

 

 

 

np.array([1,2,3])-np.array([4,5,6])

 

 

×

 

 

Out[5]:

array([-3, -3, -3])

. . .

In [9]:

 

 

 

 

 

 

 

 

 

 

my_list = [[1,2,3],[4,5,6]]

x = np.array(my_list)

print(x)

print("x's shape is : ",x.shape)

​

 

 

×

 

 

 

[[1 2 3]
 [4 5 6]]
x's shape is :  (2, 3)

. . .

In [10]:

 

 

 

 

 

 

 

 

 

 

 list  = np.arange(0,30,2)

 print(list)

 

 

×

 

 

 

[ 0  2  4  6  8 10 12 14 16 18 20 22 24 26 28]

. . .

In [12]:

 

re

 

 

 

 

 

 

 

 

new_array = list.reshape(3,5)

print(new_array)

 

 

×

 

 

 

[[ 0  2  4  6  8]
 [10 12 14 16 18]
 [20 22 24 26 28]]

. . .

In [18]:

 

print('diag:\n',np.diag(my_list))

 

 

 

 

x

 

 

 

print('ones:\n',np.ones((3,2)))

print('zeros:\n',np.zeros((3,2)))

print('eye:\n',np.eye((3)))

print('diag:\n',np.diag((1,2,3)))

print('diag:\n',np.diag(my_list))

 

 

×

 

 

 

ones:
 [[ 1.  1.]
 [ 1.  1.]
 [ 1.  1.]]
zeros:
 [[ 0.  0.]
 [ 0.  0.]
 [ 0.  0.]]
eye:
 [[ 1.  0.  0.]
 [ 0.  1.  0.]
 [ 0.  0.  1.]]
diag:
 [[1 0 0]
 [0 2 0]
 [0 0 3]]
diag:
 [1 5]

. . .

In [20]:

 

 

 

 

 

 

 

 

 

 

x=np.arange(16).reshape((4,4))

print(x)

 

 

×

 

 

 

[[ 0  1  2  3]
 [ 4  5  6  7]
 [ 8  9 10 11]
 [12 13 14 15]]

. . .

In [21]:

 

print('diag:\n',np.diag(x,1)) print('diag:\n',np.diag(x,-1))

 

 

 

 

x

 

 

 

print('diag:\n',np.diag(x,1))

print('diag:\n',np.diag(x,-1))

 

 

×

 

 

 

diag:
 [ 1  6 11]
diag:
 [ 4  9 14]

. . .

In [22]:

 

2

 

 

 

 

 

 

 

 

print('diag:\n',np.diag(x,2))

print('diag:\n',np.diag(x,-2))

 

 

×

 

 

 

diag:
 [2 7]
diag:
 [ 8 13]

. . .

In [23]:

 

print("*操作：\n",np.array([1,2,3]*3)) print("*操作：\n",np.repeat([1,2,3],3))

 

 

 

 

x

 

 

 

print("*操作：\n",np.array([1,2,3]*3))

print("*操作：\n",np.repeat([1,2,3],3))

 

 

×

 

 

 

*操作：
 [1 2 3 1 2 3 1 2 3]
*操作：
 [1 1 1 2 2 2 3 3 3]

. . .

In [25]:

 

 

 

 

 

 

 

 

 

 

p1 = np.ones((3,3))

p2 = np.arange(9).reshape(3,3)

print("纵向+\n",np.vstack((p1,p2)))

print("横向+\n",np.hstack((p1,p2)))

 

 

×

 

 

 

纵向+
 [[ 1.  1.  1.]
 [ 1.  1.  1.]
 [ 1.  1.  1.]
 [ 0.  1.  2.]
 [ 3.  4.  5.]
 [ 6.  7.  8.]]
横向+
 [[ 1.  1.  1.  0.  1.  2.]
 [ 1.  1.  1.  3.  4.  5.]
 [ 1.  1.  1.  6.  7.  8.]]

. . .

In [27]:

 

 

 

 

 

 

 

 

 

 

  print('p1 + p2 \n',p1+p2)

  print('p1 * p2 \n',p1*p2)

  print('p2^2 \n',p2**2)

  print('p1 . p2 \n',p1.dot(p2))

 

 

×

 

 

 

p1 + p2 
 [[ 1.  2.  3.]
 [ 4.  5.  6.]
 [ 7.  8.  9.]]
p1 * p2 
 [[ 0.  1.  2.]
 [ 3.  4.  5.]
 [ 6.  7.  8.]]
p2^2 
 [[ 0  1  4]
 [ 9 16 25]
 [36 49 64]]
p1 . p2 
 [[  9.  12.  15.]
 [  9.  12.  15.]
 [  9.  12.  15.]]

. . .

In [ ]:

 

 

 

 

 

 

 

 

 

 

 

 

 

×

 

 

 

. . .