NumPy.py

import numpy as np
import time
import sys
import matplotlib.pyplot as plt


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

b = np.array([[1,2,3], [4,5,6]])
print(b)

S = range(1000)
print(S)
print(sys.getsizeof(5)*len(S)) # List - size of one element multiplied by the number of all elements,
                                # so we got the size of all elements
print(sys.getsizeof(5)) #size of one element

D = np.arange(1000)
print(D.size * D.itemsize) # NumPy - size of one element multiplied by the number of all elements,
                            # so we got the size of all elements

SIZE = 1000000
L1 = range(SIZE)
L2 = range(SIZE)

A1 = np.arange(SIZE)
A2 = np.arange(SIZE)

start = time.time()
result = [(x,y) for x,y in zip(L1, L2)]

print ((time.time() - start) * 1000 ) #runtime of List

start = time.time()
result = A1 + A2

print ((time.time() - start) * 1000 ) #runtime of Numpy


a = np.array([(1,2,3),(2,3,4)])
print(a.ndim) #dimention of array
print(a.itemsize) #byte size of each element
print(a.dtype) #data type
print(a.size) #size of array
print(a.shape) #shape of array
a = a.reshape(3, 2) #reshape into 3 rows and 2 collums
print(a)

a = np.array([(1,2,3),(2,3,4),(5,6,8)])
print(a[0:2,1]) #slicing

a = np.linspace(1,3,10) #slicing
print(a)

a = np.array([(1,2,3),(2,3,4),(5,6,8)])

print(a.max()) #maximum element in array
print(a.min()) #minimum element in array
print(a.sum(), "\n") #sum elements in array

print(a.sum(axis=1),"\n") #horizontal axis ->
print(a.sum(axis=0), "\n") #vertical axis |
print("\n", np.sqrt(a)) #square
print("\n", np.std(a)) #Standart Deviation (средне квадратическое отклонение)

b = np.array([(7,5,10),(25,34,2),(7,1,3)])

print("\n", a+b) #sum of matrices
print("\n", a-b) #substraction of matrices
print("\n", a*b) #multiply of matrices
print("\n", a/b) #divide of matrices

print("\n"*2,np.vstack((a,b))) #concatenation along the first axis ->
print("\n"*2,np.hstack((a,b))) #stack arrays in sequence horizontaly (column wise)
print("\n", a.ravel()) #into a single column

x = np.arange(0, 3 * np.pi, 0.1 )
y = np.sin(x)
z = np.cos(x)
plt.plot(x,y) #sin plot
plt.plot(x,z) #cos plot
plt.show()

ar = np.array([2, 5, 10])
print("\n", np.exp(ar)) #exponential
print("\n", np.log(ar)) #natural log с основой 2
print(np.log10(ar)) #с основой 10