scipy.spatial.transform.Rotation.

random#

static Rotation.random(num=None, rng=None, *, shape=None, random_state=None)[source]#

Generate rotations that are uniformly distributed on a sphere.

Formally, the rotations follow the Haar-uniform distribution over the SO(3) group.

Parameters:
numint or None, optional

Number of random rotations to generate. If None (default), then a single rotation is generated.

rng{None, int, numpy.random.Generator}, optional

If rng is passed by keyword, types other than numpy.random.Generator are passed to numpy.random.default_rng to instantiate a Generator. If rng is already a Generator instance, then the provided instance is used. Specify rng for repeatable function behavior.

If this argument is passed by position or random_state is passed by keyword, legacy behavior for the argument random_state applies:

  • If random_state is None (or numpy.random), the numpy.random.RandomState singleton is used.

  • If random_state is an int, a new RandomState instance is used, seeded with random_state.

  • If random_state is already a Generator or RandomState instance then that instance is used.

Changed in version 1.15.0: As part of the SPEC-007 transition from use of numpy.random.RandomState to numpy.random.Generator, this keyword was changed from random_state to rng. For an interim period, both keywords will continue to work, although only one may be specified at a time. After the interim period, function calls using the random_state keyword will emit warnings. The behavior of both random_state and rng are outlined above, but only the rng keyword should be used in new code.

shapetuple of ints, optional

Shape of random rotations to generate. If specified, num must be None.

Returns:
random_rotationRotation instance

Contains a single rotation if num is None. Otherwise contains a stack of num rotations.

See also

scipy.stats.special_ortho_group

Notes

This function is optimized for efficiently sampling random rotation matrices in three dimensions. For generating random rotation matrices in higher dimensions, see scipy.stats.special_ortho_group.

Examples

>>> from scipy.spatial.transform import Rotation as R

Sample a single rotation:

>>> R.random().as_euler('zxy', degrees=True)
array([-110.5976185 ,   55.32758512,   76.3289269 ])  # random

Sample a stack of rotations:

>>> R.random(5).as_euler('zxy', degrees=True)
array([[-110.5976185 ,   55.32758512,   76.3289269 ],  # random
       [ -91.59132005,  -14.3629884 ,  -93.91933182],
       [  25.23835501,   45.02035145, -121.67867086],
       [ -51.51414184,  -15.29022692, -172.46870023],
       [ -81.63376847,  -27.39521579,    2.60408416]])
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