This document is based on PEP 8 – Style Guide for Python Code. There will be quite a few quoted passages (albeit with commentary). Any text block shown in

This is a short quote.

or

Example 1: Example Quote

This is a quoted passage.

is a passage extracted from PEP 8 – Style Guide for Python Code.

Let us start with the last paragraph of the PEP 8 Introduction.

Many projects have their own coding style guidelines. In the event of any conflicts, such project-specific guides take precedence for that project.

You will find the Python code for this course (along with code in other courses) follow the standard PEP 8 style quite closely. You will find exceptions with mathematical notations, e.g., when naming matrices and vectors for Least Squares Approximation.

I have adopted the convention of… if the notation comes from a discipline then prepend the discipline to the variable name. For example, the Newton’s Gravitational Constant “$G$” would become physics_G.

You will find that eighty (80) characters is the maximum line length in most Python code that I write. Take a minute to read through the quoted passage from PEP 8 - Maximum Line Length.

Example 2: PEP 8 - Maximum Line Length (Excerpt)

Limit all lines to a maximum of 79 characters.

For flowing long blocks of text with fewer structural restrictions (docstrings or comments), the line length should be limited to 72 characters.

Limiting the required editor window width makes it possible to have several files open side by side, and works well when using code review tools that present the two versions in adjacent columns.

The default wrapping in most tools disrupts the visual structure of the code, making it more difficult to understand. The limits are chosen to avoid wrapping in editors with the window width set to 80, even if the tool places a marker glyph in the final column when wrapping lines. Some web based tools may not offer dynamic line wrapping at all.

…

The preferred way of wrapping long lines is by using Python’s implied line continuation inside parentheses, brackets and braces. Long lines can be broken over multiple lines by wrapping expressions in parentheses. These should be used in preference to using a backslash for line continuation.

def main():
    """
    Compute the area of a room and the cost of
    flooring for the room
    """

    # Construct the house within the build function
    house = build_house()

    print(house)

    # Upgrade the flooring in a second duplicate house
    duplicate_house = upgrade_flooring(house)

    print(f"house == duplicate_house -> {house == duplicate_house}")
    print(f"&house == &duplicate_house -> {house is duplicate_house}")
    print()

    print(house)
    print(duplicate_house)

    # Get all the flooring costs with a 10% discount
    costs = [discount_flooring(room) for room in duplicate_house]

    for room_cost in costs:
        print(f"{room_cost:.2f}")

    total = sum(costs)
    min_c = min(costs)
    max_c = max(costs)

    print(f"Total: {total:.2f}")
    print(f"Min  : {min_c:.2f}")
    print(f"Max  : {max_c:.2f}")

The Pet Peeves section of PEP 8 summarizes a few rules (most of which you will find are considered best practices in C++, Java, and Rust).

Example 3: Selected Pet Peeves

Avoid extraneous whitespace in the following situations:

• Immediately inside parentheses, brackets or braces

• Between a trailing comma and a following close [sic] parenthesis

• Immediately before a comma, semicolon, or colon:

• Immediately before the open parenthesis that starts the argument list of a function call

• More than one space around an assignment (or other) operator to align it with another:

The full list is quite a bit longer (and includes examples). However, like many of these conventions… the omitted guidelines will be demonstrated in the lecture examples.