Teaching Kids Programming – The Endless Iterator Cycle (from itertools) in Python

Teaching Kids Programming: Videos on Data Structures and Algorithms

The cycle function from itertools in Python provides an endless iterator given a iterables. For example, one possible implementation of such is as follows. The first time we go through the given iterables, we save the elements in a copy, and then we can yield the elements from the saved copy endlessly…

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def cycle(x):
    a = []
    for i in x:
        yield i
        a.append(i)
    while a:
        for i in a:
            yield i

def cycle(x):
    a = []
    for i in x:
        yield i
        a.append(i)
    while a:
        for i in a:
            yield i

We can use it this way to have a endless iterator that cycles a iterable:

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from itertools import cycle
 
g = cycle((1, 2, 3))
for _ in range(10):
    print(next(g))

from itertools import cycle

g = cycle((1, 2, 3))
for _ in range(10):
    print(next(g))

This will print 1, 2, 3, 1, 2, 3, 1, 2, 3, 1 …

The iterator in Python can only move/advance forward.

Python’s itertools.cycle function is a powerful tool for creating infinite iterators. It enables users to create an infinite iterator from a finite iterable object. This can be used to create a cycle of values that repeat over and over again.

One of the most common uses of itertools.cycle is in creating a generator that yields an infinite stream of values. By combining itertools.cycle with the next() function, users can create a generator that produces an infinite stream of values from a finite iterable object. This is useful for creating repeatable sequences of values that can be used for data manipulation, machine learning tasks, or looping through long lists. For example, a cycling generator could be used to generate an infinite set of random numbers or to cycle through a list of names.

Itertools.cycle is also useful for creating a loop in a program. By using the loop to cycle through a finite iterable object, the loop can be used to repeat a piece of code until a specific condition is met. This is especially helpful when building user interfaces, as it allows the user to keep entering data until a certain limit is reached.

Overall, Python’s itertools.cycle function is a powerful tool for creating infinite iterators from finite iterable objects. It is useful for creating generators, loops, and user interfaces that require cycling through a list of values. Try it out today and see how it can help you automate repetitive tasks.

–EOF (The Ultimate Computing & Technology Blog) —

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