DuckieDai Shoelace Area Python Program

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geometry · MIT License

Overview

Calculate a polygon's area from vertices entered in clockwise or counterclockwise order.

Usage

Inputs

At least three ordered polygon vertices
Finite coordinate values between -1e100 and 1e100

Outputs

Polygon area from the shoelace formula

Units: Coordinates use one coordinate system; area uses square coordinate units.

Assumptions and limitations

Assumptions

Vertices are entered in order around a non-self-crossing polygon.

Constraints

The TI program requires at least three vertices.

Known failures

Self-crossing or unordered vertices can produce an unintended area.

Compatibility and review

Review status: Tested on a TI calculator
Tested on: TI-84 Plus CE Python; OS 5.8.3; Python App 5.8.3.0048; exact source owner-tested through TI Connect CE
What happened: Owner confirmed the supplied shoelace area program runs on the physical calculator.
Dependencies: No imports
Suggested calculator name: SHOELACE — you can give it another valid, unique name when you transfer it
Desktop test cases: Not available for this interactive-only source

This exact source auto-launches an interactive calculator session, so compatibility evidence comes from the recorded physical-device review rather than an importable desktop fixture.

Browser preview

Try a three-vertex shoelace calculation

This browser preview is deliberately limited to a triangle. The TI program accepts any number of ordered vertices from three onward.

Simulation boundary: This preview uses a reviewed browser adapter. It does not execute the downloaded Python and does not prove TI-Python or calculator compatibility.

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Exact reviewed bytes

Source code

Download .py

View source below, copy it when JavaScript is available, or download the exact .py bytes.

"""DuckieDai Shoelace Area for TI-84 Plus CE Python."""


def duckiedai_intro(program_name, wait=True):
    """Show the reusable DuckieDai program opening."""
    title = program_name[:16]
    empty = 16 - len(title)
    left = empty // 2
    right = empty - left

    print("+----------------------+")
    print("|   " + " " * left + title + " " * right + "   |")
    print("|                      |")
    print("|       __             |")
    print("|   ___(o )>  quack!   |")
    print("|   \\ <_. )           |")
    print("|    `---'             |")
    print("|     by DuckieDai     |")
    print("+----------------------+")
    print("Loading...")

    if wait:
        input("Press enter to start ")
        print("\n" * 6)


def number(prompt):
    """Allow positive, negative, or zero coordinates."""
    while True:
        try:
            value = float(input(prompt))

            if value > -1e100 and value < 1e100:
                return value

        except ValueError:
            pass

        print("Enter a valid number.")


def vertex_count():
    """Require at least three polygon vertices."""
    while True:
        try:
            count = int(input("Number of vertices: "))

            if count >= 3:
                return count

        except ValueError:
            pass

        print("Enter 3 or more.")


def shoelace_area(x_values, y_values):
    """Calculate polygon area with the shoelace formula."""
    total = 0
    n = len(x_values)

    for i in range(n):

        next_i = (i + 1) % n

        total += (
            x_values[i] * y_values[next_i]
            - x_values[next_i] * y_values[i]
        )

    return abs(total) / 2


def main():
    duckiedai_intro("SHOELACE AREA")

    print("SHOELACE FORMULA")
    print("POLYGON AREA")
    print()
    print("Enter vertices in")
    print("order around polygon.")
    print()
    print("Clockwise OR")
    print("counterclockwise.")
    print()

    count = vertex_count()

    x_values = []
    y_values = []

    print()

    for i in range(count):

        print("POINT " + str(i + 1))

        x = number("x: ")
        y = number("y: ")

        x_values.append(x)
        y_values.append(y)

        print()

    area = shoelace_area(
        x_values,
        y_values
    )

    print("Using:")
    print("Shoelace Formula")
    print()
    print("Vertices: " + str(count))
    print()

    print("ANSWER")
    print("Area = " + str(area))
    print("square units")

    print()
    print("DuckieDai says: done!")


# TI-Python imports the selected AppVar rather than
# setting __name__ to main.
main()

"""DuckieDai Shoelace Area for TI-84 Plus CE Python."""
def duckiedai_intro(program_name, wait=True):
"""Show the reusable DuckieDai program opening."""
title = program_name[:16]
empty = 16 - len(title)
left = empty // 2
right = empty - left
print("+----------------------+")
print("| " + " " * left + title + " " * right + " |")
print("| |")
print("| __ |")
print("| ___(o )> quack! |")
print("| \\ <_. ) |")
print("| `---' |")
print("| by DuckieDai |")
print("+----------------------+")
print("Loading...")
if wait:
input("Press enter to start ")
print("\n" * 6)
def number(prompt):
"""Allow positive, negative, or zero coordinates."""
while True:
try:
value = float(input(prompt))
if value > -1e100 and value < 1e100:
return value
except ValueError:
pass
print("Enter a valid number.")
def vertex_count():
"""Require at least three polygon vertices."""
while True:
try:
count = int(input("Number of vertices: "))
if count >= 3:
return count
except ValueError:
pass
print("Enter 3 or more.")
def shoelace_area(x_values, y_values):
"""Calculate polygon area with the shoelace formula."""
total = 0
n = len(x_values)
for i in range(n):
next_i = (i + 1) % n
total += (
x_values[i] * y_values[next_i]
- x_values[next_i] * y_values[i]
)
return abs(total) / 2
def main():
duckiedai_intro("SHOELACE AREA")
print("SHOELACE FORMULA")
print("POLYGON AREA")
print()
print("Enter vertices in")
print("order around polygon.")
print()
print("Clockwise OR")
print("counterclockwise.")
print()
count = vertex_count()
x_values = []
y_values = []
print()
for i in range(count):
print("POINT " + str(i + 1))
x = number("x: ")
y = number("y: ")
x_values.append(x)
y_values.append(y)
print()
area = shoelace_area(
x_values,
y_values
)
print("Using:")
print("Shoelace Formula")
print()
print("Vertices: " + str(count))
print()
print("ANSWER")
print("Area = " + str(area))
print("square units")
print()
print("DuckieDai says: done!")
# TI-Python imports the selected AppVar rather than
# setting __name__ to main.
main()

Filename: SHOELACE.py
Size: 2735 bytes
SHA-256: f0f5f745c9ade2dd05b7afdd06d19edcffb0c5f25397661cf000052cc2f63ef7

Transfer and launch

Confirm that your calculator is the Python-capable model named above. Check that its OS and Python App versions match the reviewed record.
Download the .py source above and verify its SHA-256 digest if your computer provides that option.
Use TI Connect CE to send the Python file to a compatible calculator. SHOELACE is a suggested name; you may choose another valid, unique calculator name.
Open the Python App, select the program, and check sample inputs before relying on other results.

Read the complete installation, launch, troubleshooting, and removal guide.

Availability does not mean a teacher, school, or exam permits this program. Follow the applicable rules.

Version history

1.0.0 — current version, published 2026-09-24. Download this reviewed version

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