python get rotation matrix from angle code example

Example: euler angle to rotation vector python

import math
import numpy as np

# RPY/Euler angles to Rotation Vector
def euler_to_rotVec(yaw, pitch, roll):
    # compute the rotation matrix
    Rmat = euler_to_rotMat(yaw, pitch, roll)
    
    theta = math.acos(((Rmat[0, 0] + Rmat[1, 1] + Rmat[2, 2]) - 1) / 2)
    sin_theta = math.sin(theta)
    if sin_theta == 0:
        rx, ry, rz = 0.0, 0.0, 0.0
    else:
        multi = 1 / (2 * math.sin(theta))
        rx = multi * (Rmat[2, 1] - Rmat[1, 2]) * theta
        ry = multi * (Rmat[0, 2] - Rmat[2, 0]) * theta
        rz = multi * (Rmat[1, 0] - Rmat[0, 1]) * theta
    return rx, ry, rz

def euler_to_rotMat(yaw, pitch, roll):
    Rz_yaw = np.array([
        [np.cos(yaw), -np.sin(yaw), 0],
        [np.sin(yaw),  np.cos(yaw), 0],
        [          0,            0, 1]])
    Ry_pitch = np.array([
        [ np.cos(pitch), 0, np.sin(pitch)],
        [             0, 1,             0],
        [-np.sin(pitch), 0, np.cos(pitch)]])
    Rx_roll = np.array([
        [1,            0,             0],
        [0, np.cos(roll), -np.sin(roll)],
        [0, np.sin(roll),  np.cos(roll)]])
    # R = RzRyRx
    rotMat = np.dot(Rz_yaw, np.dot(Ry_pitch, Rx_roll))
    return rotMat

roll = 2.6335
pitch = 0.4506
yaw = 1.1684

print "roll = ", roll
print "pitch = ", pitch
print "yaw = ", yaw
print ""

rx, ry, rz = euler_to_rotVec(yaw, pitch, roll)

print rx, ry, rz