How to Iterate Over a Circular List in Python Efficiently?

Circular List Iteration in Python

You're seeking an effective method to iterate over a circular list in Python, starting each iteration with the last visited item. This problem arises when working with use cases like connection pools, where you need to locate an available connection within a loop.

Solution Using itertools.cycle

The ideal solution in Python is to employ the itertools.cycle function, which serves the precise purpose of supporting circular list iteration. Here's how:

<code class="python">from itertools import cycle

lst = ['a', 'b', 'c']

pool = cycle(lst)

for item in pool:
    print(item)</code>

The above code will print the elements in an endless loop:

"a b c a b c ..."

To manually advance the iterator and retrieve values one by one, simply use next(pool):

<code class="python">next(pool)  # returns 'a'
next(pool)  # returns 'b'</code>

This provides a neat and efficient way to iterate over circular lists in Python.

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