mushroom_rl/utils/angles.py
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from math import fmod
import numpy as np
from scipy.spatial.transform import Rotation as R
def normalize_angle_positive(angle):
"""
Wrap the angle between 0 and 2 * pi.
Args:
angle (float): angle to wrap.
Returns:
The wrapped angle.
"""
pi_2 = 2. * np.pi
return fmod(fmod(angle, pi_2) + pi_2, pi_2)
def normalize_angle(angle):
"""
Wrap the angle between -pi and pi.
Args:
angle (float): angle to wrap.
Returns:
The wrapped angle.
"""
a = normalize_angle_positive(angle)
if a > np.pi:
a -= 2. * np.pi
return a
def shortest_angular_distance(from_angle, to_angle):
"""
Compute the shortest distance between two angles
Args:
from_angle (float): starting angle;
to_angle (float): final angle.
Returns:
The shortest distance between from_angle and to_angle.
"""
return normalize_angle(to_angle - from_angle)
def quat_to_euler(quat):
"""
Convert a quaternion to euler angles.
Args:
quat (np.ndarray): quaternion to be converted, must be in format [w, x, y, z]
Returns:
The euler angles [x, y, z] representation of the quaternion
"""
if len(quat.shape) < 2:
return R.from_quat(quat[[1, 2, 3, 0]]).as_euler('xyz')
else:
return R.from_quat(quat[[1, 2, 3, 0], :].T).as_euler('xyz').T
def euler_to_quat(euler):
"""
Convert euler angles into a quaternion.
Args:
euler (np.ndarray): euler angles to be converted
Returns:
Quaternion in format [w, x, y, z]
"""
if len(euler.shape) < 2:
return R.from_euler('xyz', euler).as_quat()[[3, 0, 1, 2]]
else:
return R.from_euler('xyz', euler.T).as_quat()[:, [3, 0, 1, 2]].T
def mat_to_euler(mat):
"""
Convert a rotation matrix to euler angles.
Args:
mat (np.ndarray): a 3d rotation matrix.
Returns:
The euler angles [x, y, z] representation of the quaternion
"""
return R.from_matrix(mat).as_euler('xyz')
def euler_to_mat(euler):
"""
Convert euler angles into a a rotation matrix.
Args:
euler (np.ndarray): euler angles [x, y, z] to be converted.
Returns:
The rotation matrix representation of the euler angles
"""
return R.from_euler('xyz', euler).as_matrix()