How does `zip([iter(s)]n)` split a list into chunks of equal size in Python?

Understanding zip([iter(s)]n) in Python

Splitting a list into chunks of equal size is a common task in programming. Python provides an efficient solution using the zip([iter(s)]n) expression.

The iter() function returns an iterator over a sequence, while the arg syntax unpacks a sequence into arguments for a function call. In the expression, [x] n creates a list containing n quantity of x, i.e. a list of length n with each element set to x.

To demonstrate how it works, let's expand it with verbose code:

s = [1,2,3,4,5,6,7,8,9]
n = 3
x = iter(s)
y = iter(s)
z = iter(s)
list(zip(x, y, z))

This produces the following output:

[(1,2,3),(4,5,6),(7,8,9)]

As you can see, the zip() function combines the first element from each iterator to form the first tuple, the second element to form the second tuple, and so on. By providing the same iterator multiple times, we effectively divide the sequence into chunks of the specified size.

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