Python Iterators: Beginner Python tutorials 15 | Better4Code

Python iterators are objects that can be iterated upon, meaning that you can access each element of an iterable one at a time. Iterators are used to iterate over sequences like lists, tuples, and strings. In this article, we’ll explore Python iterators and provide some examples to illustrate their usage.

 

What is Python Iterator?

In Python, an iterator is an object that implements the iterator protocol, which consists of two methods: iter() and next(). The iter() method returns the iterator object itself, and the next() method returns the next value in the iteration. If there are no more values to return, the next() method raises the StopIteration exception.

 

Creating Python Iterators

To create an iterator in Python, you need to define a class that implements the iterator protocol. Here is an example:

class MyIterator:
    def __init__(self, limit):
        self.limit = limit
        self.current = 0

    def __iter__(self):
        return self

    def __next__(self):
        if self.current < self.limit:
            result = self.current
            self.current += 1
            return result
        else:
            raise StopIteration

This creates a new iterator class called MyIterator that iterates from 0 to the specified limit. The iter() method returns the iterator object itself, and the next() method returns the next value in the iteration.

 

Using an Iterator

Once you have created an iterator in Python, you can use it to iterate over an iterable object. Here is an example:

my_iterator = MyIterator(5)

for i in my_iterator:
    print(i)

This creates a new instance of the MyIterator class called my_iterator, and then uses it to iterate over a range of 5 values. The for loop calls the next() method of the iterator object until the StopIteration exception is raised.

 

Built-in Iterators in Python

Python provides several built-in iterators that you can use to iterate over common sequences like lists, tuples, and strings. Here are some examples:

my_list = [1, 2, 3, 4, 5]
my_iterator = iter(my_list)

for i in my_iterator:
    print(i)

This creates a new list called my_list, and then uses the built-in iter() function to create an iterator object from it. The for loop then uses the iterator object to iterate over the values of the list.

my_string = "Hello, World!"
my_iterator = iter(my_string)

for i in my_iterator:
    print(i)

This creates a new string called my_string, and then uses the built-in iter() function to create an iterator object from it. The for loop then uses the iterator object to iterate over the characters of the string.

 

Conclusion

In this article, we explored Python iterators and provided examples to illustrate their usage. We learned how to create an iterator class, use it to iterate over an iterable object, and use built-in iterators to iterate over common sequences. By understanding these concepts, you can write more efficient and concise code that takes advantage of the powerful iteration features of Python.