Python – Convert List to custom overlapping nested list

Given a list, the task is to write a Python program to convert it into a custom overlapping nested list based on element size and overlap step.

Examples:

Input: test_list = [3, 5, 6, 7, 3, 9, 1, 10], step, size = 2, 4
Output: [[3, 5, 6, 7], [6, 7, 3, 9], [3, 9, 1, 10], [1, 10]]
Explanation: Rows sliced for size 4, and overcoming started after 2 elements of current row.

Input: test_list = [3, 5, 6, 7, 3, 9, 1, 10], step, size = 2, 3
Output: [[3, 5, 6], [6, 7, 3], [3, 9, 1], [1, 10]]
Explanation: Rows sliced for size 3, and overcoming started after 2 elements of current row.

Method #1: Using list slicing + loop

In this, row size is managed by slicing operation and overlap step is managed by step mentioned in range() while using a loop for iteration.

Python3

# Python3 code to demonstrate working of
# Convert List to custom overlapping Matrix
# Using list slicing + loop

# initializing list
test_list = [3, 5, 6, 7, 3, 9, 1, 10]

# printing original list
print("The original list is : " + str(test_list))

# initializing step, size
step, size = 2, 4

res = []
for idx in range(0, len(test_list), step):

    # slicing list
    res.append(test_list[idx: idx + size])

# printing result
print("The created Matrix : " + str(res))

Output:

The original list is : [3, 5, 6, 7, 3, 9, 1, 10]

The created Matrix : [[3, 5, 6, 7], [6, 7, 3, 9], [3, 9, 1, 10], [1, 10]]

Time Complexity: O(n)
Auxiliary Space: O(n)

Method #2: Using list comprehension 

In this, similar functionality as the above method is used with a variation of having shorthand using list comprehension.

Python3

# Python3 code to demonstrate working of
# Convert List to custom overlapping Matrix
# Using list comprehension

# initializing list
test_list = [3, 5, 6, 7, 3, 9, 1, 10]

# printing original list
print("The original list is : " + str(test_list))

# initializing step, size
step, size = 2, 4

# list comprehension used as shorthand to solve problem
res = [test_list[idx: idx + size] for idx in range(0,
                                                   len(test_list),
                                                   step)]

# printing result
print("The created Matrix : " + str(res))

Output:

The original list is : [3, 5, 6, 7, 3, 9, 1, 10]

The created Matrix : [[3, 5, 6, 7], [6, 7, 3, 9], [3, 9, 1, 10], [1, 10]]

Time complexity: O(n), where n is the length of the input list. 
Auxiliary space: O(m)