gmtry

A lightweight Python geometry library.

gmtry provides Python classes for common geometric shapes, with calculations for area, perimeter, angles, distances, and other geometric properties. It is designed to offer a simple, consistent API for working with geometry.

Features

• 2D geometry — triangles, quadrilaterals, polygons, ellipses, and circles
• Geometric properties — areas, perimeters, angles, side lengths, and more
• Shape classification — identify common geometric properties and shape types
• Input validation — reject invalid dimensions and degenerate shapes
• Type hints — typed interfaces for better editor support
• Lightweight — built around Python's standard library

Installation

Install from PyPI:

pip install gmtry

Import the classes you need:

from gmtry import (
    Triangle,
    Quadrilateral,
    Rectangle,
    Square,
    Parallelogram,
    Rhombus,
    Trapezoid,
    Polygon,
    RegularPolygon,
    Ellipse,
    Circle,
)

Quick start

from gmtry import Circle, Rectangle, RegularPolygon, Triangle

circle = Circle(5)
print(circle.area)
print(circle.circumference)

rectangle = Rectangle(8, 4)
print(rectangle.area)
print(rectangle.perimeter)

triangle = Triangle(3, 4, 5)
print(triangle.area)
print(triangle.perimeter)

hexagon = RegularPolygon(6, 2)
print(hexagon.area)
print(hexagon.perimeter)

API Reference

Triangles

Triangle(a, b, c)

Represents a triangle defined by its three side lengths.

Example:

triangle = Triangle(3, 4, 5)

print(triangle.area)
print(triangle.perimeter)
print(triangle.is_right)

Quadrilaterals

Quadrilateral(a, b, c, d, diagonal_ac=...)

Represents a four-sided polygon defined by its side lengths and diagonal AC.

The diagonal is required because four side lengths alone do not uniquely determine a quadrilateral.

Example:

shape = Quadrilateral(
    5, 4, 5, 4,
    diagonal_ac=6,
)

print(shape.area)
print(shape.perimeter)

Rectangle(length, width)

Represents a rectangle defined by its length and width.

rectangle = Rectangle(8, 4)

print(rectangle.area)       # 32
print(rectangle.perimeter)  # 24

Square(side)

Represents a square. Inherits rectangle properties.

square = Square(5)

print(square.area)       # 25
print(square.perimeter)  # 20

Parallelogram(a, b, angle)

Represents a parallelogram defined by two adjacent side lengths and their included angle.

parallelogram = Parallelogram(6, 4, 60)

print(parallelogram.area)
print(parallelogram.perimeter)

Rhombus(side, angle)

Represents a rhombus defined by its side length and included angle. Inherits parallelogram properties.

rhombus = Rhombus(5, 60)

print(rhombus.area)
print(rhombus.perimeter)

Trapezoid(base_a, base_c, height, offset=0)

Represents a trapezoid using its parallel base lengths, height, and horizontal offset.

trapezoid = Trapezoid(10, 6, 4, offset=1)

print(trapezoid.area)
print(trapezoid.perimeter)

Polygons

Polygon(vertices)

Represents a simple polygon defined by an ordered sequence of 2D vertices.

Vertices must follow the polygon boundary in either clockwise or counterclockwise order. Self-intersecting and degenerate polygons are rejected.

polygon = Polygon([
    (0, 0),
    (4, 0),
    (3, 2),
    (0, 2),
])

print(polygon.area)
print(polygon.perimeter)
print(polygon.is_convex)
print(polygon.contains_point(1, 1))

Note: Polygon angles are expressed in radians.

RegularPolygon(n, side_length, center=(0, 0), rotation=0)

Represents a regular polygon with equal side lengths and equal interior angles. Inherits from Polygon.

hexagon = RegularPolygon(6, 2)

print(hexagon.area)
print(hexagon.perimeter)
print(hexagon.circumradius)
print(hexagon.inradius)

Ellipses and circles

Ellipse(a, b)

Represents an ellipse centered at the origin, defined by its two semi-axis lengths. The larger semi-axis is designated the major axis and aligned with the x-axis.

ellipse = Ellipse(5, 3)

print(ellipse.area)
print(ellipse.circumference)
print(ellipse.eccentricity)
print(ellipse.foci)

Circle(radius)

Represents a circle. Inherits ellipse properties.

circle = Circle(5)

print(circle.area)
print(circle.circumference)
print(circle.diameter)
print(circle.is_unit_circle)

Validation and numerical conventions

• Dimensions must be positive and finite where applicable.
• Invalid geometric configurations raise exceptions rather than silently producing invalid shapes.
• Polygon coordinates are represented as (x, y) tuples.
• Polygon angles and rotation values use radians.
• Floating-point calculations can introduce small numerical differences.
• Ellipse circumference is an approximation, not an exact closed-form calculation.

Development

Clone the repository and install the project in editable mode:

git clone https://github.com/zscopuv/gmtry.git
cd gmtry
python -m pip install -e .

Install the testing dependency and run the test suite:

python -m pip install pytest
python -m pytest -v

Project status

gmtry is under active development. The API and available shape classes may evolve between releases.

License

See the repository's LICENSE file for licensing terms.