Welcome to trianglelib’s documentation!¶
Example: tutorial.rst — The trianglelib tutorial¶
“There is no royal road to geometry.” — Euclid
This module makes triangle processing fun!
The beginner will enjoy how the utils module
lets you get started quickly.
>>> from trianglelib import utils
>>> utils.is_isosceles(5, 5, 7)
True
But fancier programmers can use the Triangle
class to create an actual triangle object
upon which they can then perform lots of operations.
For example, consider this Python program:
from trianglelib.shape import Triangle
t = Triangle(5, 5, 5)
print 'Equilateral?', t.is_equilateral()
print 'Isosceles?', t.is_isosceles()
Since methods like is_equilateral()
return Boolean values, this program will produce the following output:
Equilateral? True
Isosceles? True
Read the Example: guide.rst — The trianglelib guide to learn more!
Warning
This module only handles three-sided polygons; five-sided figures are right out.
Example: guide.rst — The trianglelib guide¶
Whether you need to test the properties of triangles,
or learn their dimensions, trianglelib does it all!
Special triangles¶
There are two special kinds of triangle
for which trianglelib offers special support.
- Equilateral triangle
- All three sides are of equal length.
- Isosceles triangle
- Has at least two sides that are of equal length.
These are supported both by simple methods
that are available in the utils module,
and also by a pair of methods of the main
Triangle class itself.
Triangle dimensions¶
The library can compute triangle perimeter, area, and can also compare two triangles for equality. Note that it does not matter which side you start with, so long as two triangles have the same three sides in the same order!
>>> from trianglelib.shape import Triangle
>>> t1 = Triangle(3, 4, 5)
>>> t2 = Triangle(4, 5, 3)
>>> t3 = Triangle(3, 4, 6)
>>> print t1 == t2
True
>>> print t1 == t3
False
>>> print t1.area()
6.0
>>> print t1.scale(2.0).area()
24.0
Valid triangles¶
Many combinations of three numbers cannot be the sides of a triangle. Even if all three numbers are positive instead of negative or zero, one of the numbers can still be so large that the shorter two sides could not actually meet to make a closed figure. If \(c\) is the longest side, then a triangle is only possible if:
While the documentation
for each function in the trianglelib.utils module
simply specifies a return value for cases that are not real triangles,
the Triangle class is more strict
and raises an exception if your sides lengths are not appropriate:
>>> from trianglelib.shape import Triangle
>>> Triangle(1, 1, 3)
Traceback (most recent call last):
...
ValueError: one side is too long to make a triangle
If you are not sanitizing your user input to verify that the three side lengths they are giving you are safe, then be prepared to trap this exception and report the error to your user.
The trianglelib API reference¶
Routines for working with triangles.
The two modules inside of this package are packed with useful features for the programmer who needs to support triangles:
shape- This module provides a full-fledged Triangle object that can be instantiated and then asked to provide all sorts of information about its properties.
utils- For the programmer in a hurry, this module offers quick functions that take as arguments the three side lengths of a triangle, and perform a quick computation without the programmer having to make the extra step of creating an object.
advanced- Some advanced stuff.
The “shape” module¶
Use the triangle class to represent triangles.
The “utils” module¶
Routines to test triangle properties without explicit instantiation.
-
trianglelib.utils.compute_area(a, b, c)[source]¶ Return the area of the triangle with side lengths a, b, and c.
If the three lengths provided cannot be the sides of a triangle, then the area 0 is returned.
-
trianglelib.utils.compute_perimeter(a, b, c)[source]¶ Return the perimeer of the triangle with side lengths a, b, and c.
If the three lengths provided cannot be the sides of a triangle, then the perimeter 0 is returned.
-
trianglelib.utils.is_equilateral(a, b, c)[source]¶ Return whether lengths a, b, and c are an equilateral triangle.
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