Python – Random range in list

Given a List, extract random range from it. 

Input : test_list = [3, 19, 4, 8, 10, 13, 5, 7, 2, 1, 4] 
Output : [5, 7, 2, 1] 
Explanation : A random range elements are extracted of any length.

Input : test_list = [3, 19, 4, 8, 10, 13, 5, 7, 2, 1, 4] 
Output : [4, 8] 
Explanation : A random range elements are extracted of any length. 

Method : Using randrange() + slicing

randrange(): Python offers a function that can generate random numbers from a specified range and also allowing rooms for steps to be included, called randrange() in random module.

In this, we extract index of list, and for first index, and then again employ the function to get end part of range using randrange() from start index to list length. The range is extracted using slicing.

Python3

# Python3 code to demonstrate working of
# Random range in list
# Using randrange() + slicing
import random


# function to Random range in list
def rabdomRangeList(test_list):
    # getting ranges
    strt_idx = random.randrange(0, len(test_list) - 1)
    end_idx = random.randrange(strt_idx, len(test_list) - 1)

    # getting range elements
    res = test_list[strt_idx: end_idx]

    return str(res)


# Driver Code
# initializing list
input_list1 = [3, 19, 4, 8, 10, 13, 5, 7, 2, 1, 4]

# printing original list
print("\nThe original list is : ", input_list1)

# printing result
print("Required List : " + rabdomRangeList(input_list1))


# initializing list
input_list2 = [3, 19, 4, 8, 10, 13, 5, 7, 2, 1, 4]

# printing original list
print("\nThe original list is : ", input_list2)

# printing result
print("Required List : " + rabdomRangeList(input_list2))


# initializing list
input_list3 = [3, 19, 4, 8, 10, 13, 5, 7, 2, 1, 4]

# printing original list
print("\nThe original list is : ", input_list3)

# printing result
print("Required List : " + rabdomRangeList(input_list3))

Output:

The original list is :  [3, 19, 4, 8, 10, 13, 5, 7, 2, 1, 4]
Required List : [19]

The original list is :  [3, 19, 4, 8, 10, 13, 5, 7, 2, 1, 4]
Required List : [10, 13, 5, 7]

The original list is :  [3, 19, 4, 8, 10, 13, 5, 7, 2, 1, 4]
Required List : []

Time Complexity: O(n) where n is the number of elements in the list 
Auxiliary Space: O(n) additional space of size n is created where n is the number of elements in the list