Random Numbers in Python
Last Updated :
05 May, 2023
Python defines a set of functions that are used to generate or manipulate random numbers through the random module.
Functions in the random module rely on a pseudo-random number generator function random(), which generates a random float number between 0.0 and 1.0. These particular type of functions is used in a lot of games, lotteries, or any application requiring a random number generation.
Let us see an example of generating a random number in Python using the random() function.
Python3
import random
num = random.random()
print(num)
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Output:
0.30078080420602904
Different Ways to Generate a Random Number in Python
There are a number of ways to generate a random numbers in Python using the functions of the Python random module. Let us see a few different ways.
Generating a Random number using choice()
Python random.choice() is an inbuilt function in the Python programming language that returns a random item from a list, tuple, or string.
Python3
import random
list1 = [1, 2, 3, 4, 5, 6]
print(random.choice(list1))
string = "striver"
print(random.choice(string))
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Output:
5
t
Generating a Random Number using randrange()
The random module offers a function that can generate Python random numbers from a specified range and also allows room for steps to be included, called randrange().
Python3
import random
print("A random number from list is : ", end="")
print(random.choice([1, 4, 8, 10, 3]))
print("A random number from range is : ", end="")
print(random.randrange(20, 50, 3))
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Output:
A random number from list is : 4
A random number from range is : 41
Generating a Random number using seed()
Python random.seed() function is used to save the state of a random function so that it can generate some random numbers in Python on multiple executions of the code on the same machine or on different machines (for a specific seed value). The seed value is the previous value number generated by the generator. For the first time when there is no previous value, it uses the current system time.
Python3
import random
print("A random number between 0 and 1 is : ", end="")
print(random.random())
random.seed(5)
print("The mapped random number with 5 is : ", end="")
print(random.random())
random.seed(7)
print("The mapped random number with 7 is : ", end="")
print(random.random())
random.seed(5)
print("The mapped random number with 5 is : ", end="")
print(random.random())
random.seed(7)
print("The mapped random number with 7 is : ", end="")
print(random.random())
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Output:
A random number between 0 and 1 is : 0.510721762520941
The mapped random number with 5 is : 0.6229016948897019
The mapped random number with 7 is : 0.32383276483316237
The mapped random number with 5 is : 0.6229016948897019
The mapped random number with 7 is : 0.32383276483316237
Generating a Random number using shuffle()
The shuffle() function is used to shuffle a sequence (list). Shuffling means changing the position of the elements of the sequence. Here, the shuffling operation is in place.
Python3
import random
sample_list = ['A', 'B', 'C', 'D', 'E']
print("Original list : ")
print(sample_list)
random.shuffle(sample_list)
print("\nAfter the first shuffle : ")
print(sample_list)
random.shuffle(sample_list)
print("\nAfter the second shuffle : ")
print(sample_list)
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Output:
Original list :
['A', 'B', 'C', 'D', 'E']
After the first shuffle :
['A', 'B', 'E', 'C', 'D']
After the second shuffle :
['C', 'E', 'B', 'D', 'A']
Generating a Random number using uniform()
The uniform() function is used to generate a floating point Python random number between the numbers mentioned in its arguments. It takes two arguments, lower limit(included in generation) and upper limit(not included in generation).
Python3
import random
li = [1, 4, 5, 10, 2]
print("The list before shuffling is : ", end="")
for i in range(0, len(li)):
print(li[i], end=" ")
print("\r")
random.shuffle(li)
print("The list after shuffling is : ", end="")
for i in range(0, len(li)):
print(li[i], end=" ")
print("\r")
print("The random floating point number between 5 and 10 is : ", end="")
print(random.uniform(5, 10))
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Output:
The list before shuffling is : 1 4 5 10 2
The list after shuffling is : 2 1 4 5 10
The random floating point number between 5 and 10 is : 5.183697823553464
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