Python - Maximum element in consecutive subsets

We are given a list of numbers and a fixed integer k. The task is to determine the maximum number in every consecutive block of k elements. For instance, consider the list [1,3,2,5,4,6,8,7] with k=3. This list can be divided into consecutive subsets: the first subset is [1,3,2], the next is [3,2,5] followed by [2,5,4] then [5,4,6], next [4,6,8], and finally [6,8,7]. The maximum values from these subsets are 3, 5, 5, 6, 8, and 8 respectively, yielding the final output [3,5,5,6,8,8].

Using a Loop

A simple loop can be used to iterate through each consecutive subset find the maximum element within each subset and track overall maximum. This method provides a straightforward approach to finding the largest element in consecutive groups.

a = [1, 3, 2, 5, 4, 6, 8, 7]
k = 3
maxi = []
for i in range(len(a) - k + 1):
    
    # Slice the array for the current window
    subset = a[i:i + k]
    
    # Find and append the maximum of the subset
    maxi.append(max(subset))  

print(maxi)  

[3, 5, 5, 6, 8, 8]

Explanation:

• Loop iterates over list "a" slicing array into consecutive subsets of size "k" and finding the maximum element in each subset.
• Maximum values from each subset are stored in the "maxi" list which is then printed as result.

Using List Comprehension

List comprehension allows creating a list of maximum elements from consecutive subsets in a concise way by iterating over the list and applying a condition. It replaces loop with a single line of code to achieve same result.

a = [1, 3, 2, 5, 4, 6, 8, 7]
k = 3

# List comprehension to find the maximum element in each consecutive subset of size k
maxi = [max(a[i:i + k]) for i in range(len(a) - k + 1)]
print(maxi)  

[3, 5, 5, 6, 8, 8]

Explanation:

• List comprehension iterates over the list "a" slicing it into consecutive subsets of size "k" and finding maximum value in each subset.
• Maximum values from each subset are stored in "maxi" list which is then printed as result.

Using Sliding Window Approach

Sliding window approach efficiently calculates the maximum of consecutive subsets by iterating through the list while maintaining a window of fixed size. It reduces redundant calculations by updating window incrementally as it slides through the list.

a = [1, 3, 2, 5, 4, 6, 8, 7]
k = 3
maxi = []
for i in range(len(a) - k + 1):
     # Find max of the current subset
    maxi.append(max(a[i:i + k])) 

print(maxi)  

[3, 5, 5, 6, 8, 8]

Explanation:

• Loop iterates through the list "a", slicing it into consecutive subsets of size "k" and finding the maximum element in each subset.
• Maximum elements of each subset are collected in the "maxi" list, which is then printed as the result.