Reviewing and refactoring code

Case Study: Building Software in Python

Mark Pedigo

Principal Data Scientist

Benefits of periodic code review

Improved code quality
- Catch inconsistencies early
Knowledge sharing
- Collaboration
- Staying aligned
Consistency and best practices
- High standards

Two people reviewing code on a computer

Code review example

def factorial(n):
    if n == 0:
        return 1
    else:
        result = 1
        for i in range(1, n + 1):
            result *= i
        return result

Give feedback concerning:

Functionality
Readability
- Example - Unnecessary else
Edge Cases
- Example - Negative numbers for a factorial

Benefits of refactoring code

Improved code quality
Easier maintenance
Reduced technical debt

Spaghetti gets transformed to a flow chart

Refactoring example

# Original code
def factorial(n):
    if n == 0:
        return 1
    else:
        result = 1
        for i in range(1, n + 1):
            result *= i
        return result

# Refactored code
def factorial(n):
    if n < 0:
        raise ValueError("Not defined")

    if n == 0:
        return 1

    result = 1
    for i in range(1, n + 1):
        result *= i
    return result

New function for a new formula

Previous formula $$m = P \cdot \frac{r (1 + r)^N}{(1+r)^N - 1}$$ where $m$ is the monthly payment, $P$ is the loan amount, $r$ is the monthly interest rate, and $N$ is the number of monthly payments

New formula $$P = m \cdot \frac{(1+r)^N - 1}{r (1 + r)^N}$$

Roadmap

Roadmap showcasing what parts of the project we've finished and which we'll be starting

Let's practice!

Case Study: Building Software in Python