Python – Split List on next larger value

When it is required to split a list based on the next larger value, a list comprehension, the iter method and the islice methods are used. This technique allows you to divide a list into chunks of specified sizes sequentially.

Basic Example

Below is a demonstration of splitting a list into chunks of different sizes ?

from itertools import islice

my_list = [11, 22, 33, 34, 45, 26, 87, 11]
print("The list is :")
print(my_list)

length_to_split = [2, 5, 3]
print("The split length list is :")
print(length_to_split)

temp = iter(my_list)
my_result = [list(islice(temp, element)) for element in length_to_split]

print("The result is :")
print(my_result)

The list is :
[11, 22, 33, 34, 45, 26, 87, 11]
The split length list is :
[2, 5, 3]
The result is :
[[11, 22], [33, 34, 45, 26, 87], [11]]

How It Works

The solution uses these key components:

• iter() ? Creates an iterator from the original list

• islice() ? Extracts a specified number of elements from the iterator

• List comprehension ? Applies islice for each chunk size and creates sublists

Alternative Approach Using Manual Slicing

You can also split a list using traditional slicing with index tracking ?

def split_list_by_sizes(data, sizes):
    result = []
    start = 0
    
    for size in sizes:
        end = start + size
        result.append(data[start:end])
        start = end
    
    return result

my_list = [10, 20, 30, 40, 50, 60, 70, 80]
split_sizes = [3, 2, 3]

result = split_list_by_sizes(my_list, split_sizes)
print("Original list:", my_list)
print("Split sizes:", split_sizes)
print("Result:", result)

Original list: [10, 20, 30, 40, 50, 60, 70, 80]
Split sizes: [3, 2, 3]
Result: [[10, 20, 30], [40, 50], [60, 70, 80]]

Comparison

Conclusion

The islice() method with iter() provides an efficient way to split lists into chunks of varying sizes. Use manual slicing for simpler cases where memory efficiency is not a primary concern.