Python - Random Range in List

We are given a list we need to find random range in list. For example, a = [10, 20, 30, 40, 50, 60] we need to find random ranges so that given output should be random list and it changes in every execution.

Using random.sample

random.sample can randomly pick elements from the list and preserve original order.

import random

a = [10, 20, 30, 40, 50, 60]

# Create a shuffled version of the list
s = a[:]
random.shuffle(s)

# Take a random slice from the shuffled list
size = random.randint(1, len(s))
r = s[:size]
print(r)

[20, 30, 10, 40, 60, 50]

Explanation:

• A copy of list a is shuffled to avoid modifying the original.
• A random-length slice is taken from shuffled list and printed.

Using random.randint

Code creates a shuffled version of the list a to randomize the order of its elements without modifying original list. Using random.randint, it generates a random length between 1 and size of shuffled list and slices list up to this length. This produces a random sublist which is then printed.

import random

a = [10, 20, 30, 40, 50, 60]

# Generate random start and end indices
s = random.randint(0, len(a) - 1)
e = random.randint(s, len(a))

# Create a random sublist using slicing
r = a[s:e]
print(r)

[20, 30, 40]

Explanation:

• Code generates a random start index s and a random end index e (ensuring e >= s) to define a random range within the list.
• A slice is taken from original list a using indices s and e producing a random sublist r which is then printed.

Using random.sample

random.sample selects a specified number of unique elements randomly from the list without repetition. It can be used to generate random sublists of any size up to list's length.

import random

a = [10, 20, 30, 40, 50, 60]

# Randomly choose the size of the sublist
s = random.randint(1, len(a))

# Extract a random sublist while preserving the original order
r = sorted(random.sample(a, s), key=a.index)
print(r)

[20, 30]

Explanation:

• Code uses random.sample to randomly select s unique elements from the list a, with s being a random size between 1 and the length of list.
• Selected elements are sorted by their original order using key=a.index to maintain sequence as it appeared in original list.