Iterators and Generators

What are Generators and Iterators?

Generators and Iterators means generators produce values one at a time using yield. They are memory efficient for large data.

In real programs, this topic helps in processing large files. Learn the idea first, then type the program yourself and compare the output.

Why should you learn this?

• It is useful for processing large files.
• It connects with saving memory.
• It improves your ability to read, write and debug Python programs.

Important Terms

These terms are used directly in this lesson. Understand them before memorising the code.

Syntax / Basic Pattern

The simple pattern is: prepare data, apply the concept, then show the result.

def count_up_to(limit):
    number = 1
    while number <= limit:
        yield number
        number += 1
for value in count_up_to(3):
    print(value)

Complete Example Program

def count_up_to(limit):
    number = 1
    while number <= limit:
        yield number
        number += 1

for value in count_up_to(3):
    print(value)

Expected Output

Program Explanation

• def count_up_to(limit): creates a reusable function.
• number = 1 stores a value in number.
• while number <= limit: repeats the following indented statements.
• yield number performs the next step of the program logic.
• number += 1 stores a value in number +.
• for value in count_up_to(3): repeats the following indented statements.
• print(value) displays information or calculated result on the screen.

Where will you use it?

• Processing large files.
• Saving memory.
• Generating values one by one.

Common Mistakes

• Making code complex when a simple function or class is enough.
• Not handling possible errors or edge cases.
• Mixing project dependencies instead of using a virtual environment.

Practice Tasks

1. Type the program in generators-iterators.py and run it.
2. Change input values or sample data and observe the new output.
3. Create one example related to processing large files.
4. Write 5 lines explaining the logic in your own words.

Summary

Generators and Iterators is not a theory-only topic. You should be able to explain the meaning, write the example, run it successfully, and use it in a small practical program.