code: import numpy as np
  
  
  # from https://github.com/songrotek/DDPG/blob/master/ou_noise.py
  class OUNoise:
      def __init__(self, action_dimension, scale=0.1, mu=0, theta=0.15, sigma=1):#sigma=0.2
          self.action_dimension = action_dimension
          self.scale = scale
          self.mu = mu
          self.theta = theta
          self.sigma = sigma
          self.state = np.ones(self.action_dimension) * self.mu
          self.reset()
  
      def reset(self):
          self.state = np.ones(self.action_dimension) * self.mu
  
      def noise(self):
          x = self.state
          dx = self.theta * (self.mu - x) + self.sigma * np.random.randn(len(x))
          self.state = x + dx
          return self.state * self.scale
  
apis: numpy.ones