1. What Are Iterators?

An iterator is an object that can be iterated (looped) over. It uses __iter__() to return itself and __next__() to move through elements.

Example:

numbers = [1, 2, 3]
iterator = iter(numbers)
print(next(iterator))  # Outputs: 1

Iterators handle sequences efficiently, especially when working with large datasets.

2. Generators: A Lightweight Way to Create Iterators

Generators produce items one at a time and are defined using functions with yield instead of return. This keeps memory usage low and makes them ideal for processing large data.

Example:

def countdown(num):
    while num > 0:
        yield num
        num -= 1

for i in countdown(3):
    print(i)  # Outputs: 3, 2, 1

The yield statement saves the function’s state, allowing it to pick up where it left off each time it’s called.

3. Why Use Generators?

Generators are excellent for:

• Handling large datasets without loading everything into memory.
• Lazy evaluation, producing items only as needed.

4. Generator Expressions

Generator expressions provide a compact syntax for generators, similar to list comprehensions but with parentheses.

Example:

squares = (x * x for x in range(5))
print(next(squares))  # Outputs: 0

Closing Thoughts:

With generators, Python handles data streams smoothly without memory overhead, making your code efficient and scalable.