How Can I Iterate Through a List in Pairs or Groups of Elements?

Loop through Every Two Elements in a List

Iterating over every two adjacent elements in a list can be achieved with the help of specialized functions or techniques. Here's how you can accomplish this task:

1. Using pairwise() or grouped() Function:
   This method employs functions that provide a pairwise or grouped iteration over the list.

   • pairwise(): Generates pairs of elements, i.e., (s0, s1), (s2, s3), ....
   • grouped(): Extends the concept to larger groups, allowing you to retrieve n elements at a time, e.g., (s0, s1, s2, ... sn-1).

2. Implementation and Usage:

   • Define the pairwise() or grouped() function.
   • Iterate over the list using the defined function.
   • Perform desired operations on the retrieved pairs or groups of elements.

For example, to iterate over pairs of elements in a list and print their sum:

from typing import Iterable, Tuple, TypeVar

T = TypeVar("T")

def pairwise(iterable: Iterable[T]) -> Iterable[Tuple[T, T]]:
    """s -> (s0, s1), (s2, s3), ..."""
    a = iter(iterable)
    return zip(a, a)

l = [1, 2, 3, 4, 5, 6]

for x, y in pairwise(l):
    print(f"{x} + {y} = {x + y}")

This approach provides efficient iteration and avoids unnecessary list duplication.

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