NOhs / mgen

MGen: Convenient matrix generation functions

Python and its most popular packages do not offer out-of-the-box convenient functions to generate rotation matrices. While there are other projects that offer rotation and vector classes, or offer rotations via the use of quaternions, if you simply want a rotation matrix, for example if other packages require them as an input, or you do not wish to change your current data structure to use special rotation classes, the common suggestion is to implement them yourself (see for example this discussion on SE: https://stackoverflow.com/questions/6802577/rotation-of-3d-vector). However, everybody implementing their own version of the same thing can hardly be seen as ideal.

Therefore, this package provides simple functions to generate rotation matrices in 2d for a given angle or in 3d for a given axis and angle, or for three given angles (proper Euler angles or Tait-Bryan angles).

Additionally, n-dimensional rotations can be generated using an angle and two orthogonal vectors that span the plane of rotation.

Trivial example usage

Below you see examples of how to use mgen to generate rotation matrices. For further documentation please have a look here: https://mgen.readthedocs.io

import numpy as np
np.set_printoptions(suppress=True)

from mgen import rotation_around_axis
from mgen import rotation_from_angles
from mgen import rotation_around_x
from mgen import rotation_from_angle_and_plane
from mgen import rotation_from_angle
from mgen import random_matrix

# 2D example
matrix = rotation_from_angle(np.pi/2)
matrix.dot([1, 0])
# array([0., 1.])

#3D examples
matrix = rotation_from_angles([np.pi/2, 0, 0], 'XYX')
matrix.dot([0, 1, 0])
# array([0., 0., 1.])

matrix = rotation_around_axis([1, 0, 0], np.pi/2)
matrix.dot([0, 1, 0])
# array([0., 0., 1.])

matrix = rotation_around_x(np.pi/2)
matrix.dot([0, 1, 0])
# array([0., 0., 1.])

# n-dimensional example
matrix = rotation_from_angle_and_plane(np.pi/2, (0, 1, 0, 0), (0, 0, 1, 0))
matrix.dot([0, 1, 0, 0])
# array([0., 0., 1., 0.])

# n-dimensional random matrix O(n), e.g. n=27
matrix = random_matrix(27)