What are some examples of iterator patterns in Python?

What are some examples of iterator patterns in Python?

In Python, iterator patterns allow you to traverse through a collection without exposing the underlying structure. Examples include using the built-in iter() and next() functions, creating custom iterators by defining __iter__() and __next__() methods, and using generator functions with the yield keyword.

Can you show me a simple custom iterator example?

Sure! Here's a simple custom iterator that iterates over a list of numbers:

class NumberIterator:
    def __init__(self, numbers):
        self.numbers = numbers
        self.index = 0

    def __iter__(self):
        return self

    def __next__(self):
        if self.index < len(self.numbers):
            result = self.numbers[self.index]
            self.index += 1
            return result
        else:
            raise StopIteration

numbers = [1, 2, 3, 4]
iterator = NumberIterator(numbers)
for number in iterator:
    print(number)

What about using generators for iterators?

Generators are a simpler way to create iterators in Python. You can use the yield keyword to produce a sequence of values. Here's an example:

def number_generator():
    for i in range(1, 5):
        yield i

for number in number_generator():
    print(number)

Are there any built-in iterator functions I should know about?

Yes! Python has several built-in iterator functions like map(), filter(), and zip(). These functions return iterators that can be used to process data in a memory-efficient way.