Example 2: Building a Fibonacci Iterator

Example 1: Building a Basic Custom Iterator

We’ll create an iterator that generates Fibonacci numbers up to a specified limit.

Class Definition: FibonacciIterator is defined with an __init__ method that initializes the starting values of the Fibonacci sequence (self.a and self.b) and the limit up to which the numbers should be generated.
Iterator Method: The __iter__ method returns the iterator object itself.
Next Method: The __next__ method generates the next number in the Fibonacci sequence. If the current number exceeds the specified limit, it raises a StopIteration exception.
Using the Iterator: The iterator can be used with a for loop or the next() function to generate and print Fibonacci numbers up to the specified limit.

Python

class FibonacciIterator:
    def __init__(self, limit):
        self.limit = limit
        self.a = 0
        self.b = 1
    
    def __iter__(self):
        return self
    
    def __next__(self):
        if self.a > self.limit:
            raise StopIteration
        current = self.a
        self.a, self.b = self.b, self.a + self.b
        return current

# Create an instance of FibonacciIterator
fib_iterator = FibonacciIterator(100)

# Using a for loop to iterate
print("Using for loop:")
for num in fib_iterator:
    print(num)

# Using next() to iterate
print("\nUsing next() function:")
fib_iterator = FibonacciIterator(100)
print(next(fib_iterator)) 
print(next(fib_iterator))  
print(next(fib_iterator))  
print(next(fib_iterator))  
print(next(fib_iterator))  
print(next(fib_iterator)) 
print(next(fib_iterator))  
print(next(fib_iterator))  
print(next(fib_iterator))  
print(next(fib_iterator))  
print(next(fib_iterator)) 
print(next(fib_iterator))

Output:

Using for loop:
0
1
1
2
3
5
8
13
21
34
55
89

Using next() function:
0
1
1
2
3
5
8
13
21
34
55
89

Conclusion

Building a custom iterator in Python is a powerful way to create more complex and memory-efficient data traversal mechanisms. By implementing the __iter__ and __next__ methods, you can control the iteration logic and manage state between iterations. The example provided here demonstrates how to create a simple iterator that generates square numbers, but the principles can be applied to more complex scenarios as well.

How to Build a basic Iterator in Python?

Iterators are a fundamental concept in Python, allowing you to traverse through all the elements in a collection, such as lists or tuples. While Python provides built-in iterators, there are times when you might need to create your own custom iterator to handle more complex data structures or operations. In this article, we will explore how to build a basic iterator in Python from scratch.

Tags:

#python-basics #Python #python

Example 1: Building a Basic Custom Iterator

Example 2: Building a Fibonacci Iterator

Conclusion

How to Build a basic Iterator in Python?

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