Open In App

Python | Select random value from a list

Improve
Improve
Like Article
Like
Save
Share
Report

Given a list and our task is to randomly select elements from the list in Python using various functions. Selecting random numbers from a list can be used sometimes while building games, choosing a random range, etc. 

Example

Input: [2, 3, 4 , 5, 6 ]
Output: 2
Explaination:The output we are getting is a random value from the input list

Select the Random Value from a List

Below are the methods that we will cover in this article:

Select a random value from a list using random.choice()

This random.choice() function is designed for getting a Random sampling from a list in Python and hence is the most common method to achieve this task of fetching a random number from a list

Python3




import random
 
# initializing list
test_list = [1, 4, 5, 2, 7]
 
# printing original list
print("Original list is : " + str(test_list))
 
# using random.choice() to
# get a random number
random_num = random.choice(test_list)
 
# printing random number
print("Random selected number is : " + str(random_num))


Output:

Original list is : [1, 4, 5, 2, 7]
Random selected number is : 1

Select a random value from a list using random.randrange()

The random.randrange() method is used to generate a random number in a given range, we can specify the range to be 0 to the length of the list and get the index, and then the corresponding value.

Python3




import random
 
# initializing list
test_list = [1, 4, 5, 2, 7]
 
# printing original list
print("Original list is : " + str(test_list))
 
# using random.randrange() to
# get a random number
rand_idx = random.randrange(len(test_list))
random_num = test_list[rand_idx]
 
# printing random number
print("Random selected number is : " + str(random_num))


Output:

Original list is : [1, 4, 5, 2, 7]
Random selected number is : 7

Select the random value from a list using random.randint()

The random.randint() is used to generate the random number, also this can be used to generate any number in a range, and then using that number, we can find the value at the corresponding index, just like the above-mentioned technique. But it differs by the fact that it requires 2 mandatory arguments for range. 

Python3




import random
 
# initializing list
test_list = [1, 4, 5, 2, 7]
 
# printing original list
print("Original list is : " + str(test_list))
 
# using random.randint() to
# get a random number
rand_idx = random.randint(0, len(test_list)-1)
random_num = test_list[rand_idx]
 
# printing random number
print("Random selected number is : " + str(random_num))


Output:

Original list is : [1, 4, 5, 2, 7]
Random selected number is : 4

Select the random value from a list using random.random()

The random.random() method generates the floating-point numbers in the range of 0 to 1. We can also get the index value of a list using this function by multiplying the result and then typecasting it to an integer so as to get the integer index and then the corresponding list value. 

Python3




import random
 
# initializing list
test_list = [1, 4, 5, 2, 7]
 
# printing original list
print("Original list is : " + str(test_list))
 
# using random.random() to
# get a random number
rand_idx = int(random.random() * len(test_list))
random_num = test_list[rand_idx]
 
# printing random number
print("Random selected number is : " + str(random_num))


Output:

Original list is : [1, 4, 5, 2, 7]
Random selected number is : 7

Select the random value from a list using random.sample()

Python has a built-in function called random.sample().The random module contains the random.sample() function. It has the ability to choose multiple items from a list.

Python3




import random
test_list = [1, 4, 5, 2, 7]
print("Original list is : " + str(test_list))
 
print("Random element is :", random.sample(test_list, 5))


Output:

Original list is : [1, 4, 5, 2, 7]
Random element is : [7, 4, 1, 5, 2]

Select the random value from a list using random.choices()

The random.choices function is stored in the random module(). Selecting numerous items from a list or a single item from a particular sequence is handy with the help of random.choices function.

Python3




import random
test_list = [11, 44, 55, 22, 77]
print("Original list is : " + str(test_list))
 
print("Random element is :", random.choices(test_list, k=4))


Output:

the t is : [11, 44, 55, 22, 77]
Random element is : [11, 11, 44, 77]

Select the random value from a list using numpy.random.choice()

The numpy.random.choice() method is used for getting a random sample from an array in numpy. It is also possible to generate a random sample from a list by converting the list to a numpy array.
Import numpy and initialize the list. Convert the list to a numpy array. Use numpy.random.choice() method to select a random value from the array. Print the selected value.

Note: Install numpy using “pip install numpy”

Python3




import numpy as np
 
# Initializing list
test_list = [2, 3, 4, 5, 6]
 
# Converting list to numpy array
test_array = np.array(test_list)
 
# Using numpy.random.choice() to get a random number
random_num = np.random.choice(test_array)
 
# Printing the random number
print("Random selected number is : " + str(random_num))


Output:

Random selected number is : 5

Time Complexity: The time complexity of the numpy.random.choice() method is O(k), where k is the size of the sample to be generated.
Space Complexity: The space complexity of the numpy.random.choice() method is O(n), where n is the size of the array.

Select k random value from a list

Here we have grouped all elements in a pair of sizes k.

Python3




import random
 
def select_random_Ns(l, k):
    random.shuffle(l)
    res = []
    for i in range(0, len(l), k):
        res.append(l[i:i + k])
    return res
         
l = ['G', 'E', 'E', 'K', 'S', 'F', 'O', 'R', 'G', 'E', 'E', 'K', 'S']
 
print(select_random_Ns(l, 3))


Output:

[['G', 'G', 'R'], ['K', 'K', 'E'], ['O', 'F', 'E'], ['S', 'E', 'S'], ['E']]


Last Updated : 04 Aug, 2023
Like Article
Save Article
Previous
Next
Share your thoughts in the comments
Similar Reads