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12.6.1.1 use the functions of the library Random to get a pseudo-random number.
12.6.1.2 determine the function of the library Random for the specified task.
12.6.1.3 identify code snippets that use random sequence generation.
Random library
This module is designed to work with pseudo-random sequences. Such sequences are important in mathematical modeling, cryptography, and in various games.
Let's see the structure of the module.
import random
print(dir(random))
# [... 'choice', 'choices', ... 'randint', 'random', 'randrange', 'sample', ... 'shuffle'...]
How to import libraries/functions?
import random # imports all the functions in the library
print(random.randint(0,10)) # choses one random number between 0 and 10 (including both) and prints it.
from random import randint # imports only randint function from random library
print(randint(0,10)) # choses one random number between 0 and 10(including both) and prints it.
import random as rand # random library can be renamed with this way
print(rand.randint(0,10)) # choses one random number between 0 and 10 (including both) and prints it.Random function
Returns a random value between 0 and 1 (0 is inclusive and 1 is exclusive) - [0, 1)
import random
print(random.random())
#0.1149786475411152
print(int(random.random()*100))
#43Randint/randrange functions
Randint: Returns random integer in range [a, b], including both endpoints.
import random
print(random.randint(0,10)) # 10
Randrange: Chooses a random item from range(start, stop[, step]). It includes the start but not the stop.
print(random.randrange(0,100, 5)) # 0
print(random.randrange(0,100, 5)) # 10
print(random.randrange(0,100, 5)) # 65
Choice function
Note: use help(random.choice) to get help about choice function after import random statement.
import random
mylist = ["Uralsk", "Kostanay", "Nur-Sultan", "Almaty"] # list of cities
print(random.choice(mylist)) # chooses and prints a random city from mylist
# Nur-Sultan
Sample function
Chooses k unique random elements from a population sequence or set.
Returns a new list containing elements from the population while leaving the original population unchanged.
import random
print(random.sample(mylist, 2))
#['Nur-Sultan', 'Uralsk’]
print(random.sample(mylist, 60))
#ValueError: Sample larger than population or is negative
Choices function
Return a k-sized list of population elements chosen with replacement.
If the relative weights are not specified, the selections are made with equal probability.
print(random.choices(mylist, weights=[5,1,5,1], k=5))
#['Nur-Sultan', 'Uralsk', 'Uralsk', 'Nur-Sultan', 'Uralsk']
print(random.choices(mylist, weights=[5,1,5,1], k=5))
#['Nur-Sultan', 'Uralsk', 'Uralsk', 'Uralsk', 'Nur-Sultan']
print(random.choices(mylist, weights=[5,1,5,1], k=5))
#['Uralsk', 'Kostanay', 'Nur-Sultan', 'Nur-Sultan', 'Kostanay']
Shuffle function
Shuffles a given list.
import random
mylist = ['Uralsk', 'Kostanay', 'Nur-Sultan', 'Almaty’]
print(mylist) # ['Uralsk', 'Kostanay', 'Nur-Sultan', 'Almaty’]
random.shuffle(mylist)
print(mylist) # ['Almaty', 'Uralsk', 'Kostanay', 'Nur-Sultan']
Questions:
1. Name four functions of the Random module.
2. Explain how to use each function.
3. Give examples of real-life tasks where we can apply random functions.
Exercises:
Ex.1 Define function according to description.
Ex. 2 Complete the task "Storage Units – Bigger or Smaller Quiz"
https://www.101computing.net/storage-units-bigger-or-smaller-quiz/
Tasks:
Tasks on Stepik.org course "Python Programming for NIS"
1. Output random integer from 11 to 20.
2. Create a list of types of applications and output random choice.
3. Write a program to implement "Sportloto" 5 from 36. Output five random numbers in ascending order.
4. Write a program that simulates tossing coins. The number of attempts is entered from the keyboard. The program should display the results of the rolls: heads or tails.
5. A program has been written that determines the "Secret Santa" for all students in the class. Note: a student cannot be a "Secret Santa" for himself.
6. Create the program “Magic ball”.
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