Introducing the challenge

Case Study: Building Software in Python

Mark Pedigo, PhD

Principal Data Scientist

What is a case study?

Apply existing skills to a real-world problem
Prerequisite courses
- Software Engineering Principles in Python
- Intermediate Object-Oriented Programming in Python

Two people in a meeting discussing a case study

Case study scenario

Determining mortgage for new homes

Loan Officer for PyBank Financial
Build a program to
- Determine house spend
- Determine monthly payment
Disclaimer: Illustrative purposes only

Plan of action

Software automating the calculations
Using Software Engineering principles, based on classes

Stages
- Basic calculator
  - +, -, *, /, **
- Financial calculator
  - Calculate interest, interest rate
- Mortgage calculator
  - Calculate loan amount, repayments

Three calculators, increasing in size

Inheritance

Code is reused between classes

The child class (FinancialCalculator) inherits all functionality from the parent class (BasicCalculator)
Child class can implement additional functionality

class BasicCalculator:
    def multiply(self, x, y):
        result = x * y
        return result
  ...

# Child of BasicCalculator
class FinancialCalculator(BasicCalculator):
    def months_from_years(self, years):
        # Inherits the .multiply() method
        return self.multiply(years, 12)
    ...

Review of software engineering principles

Modular, clean, readable, efficient code
- Inheritance, methods
Leverage reusable libraries, frameworks, existing solutions
- Modify pre-existing code
- Streamline development
Clear documentation, code comments, usage guides
- Documentation
Testing
- doctest and unit testing

An picture of a computer surrounded by icons representing software engineering

Roadmap

Roadmap showcasing the different parts of the project.

Let's build!

Case Study: Building Software in Python