add some codes

codes/ddpg/noise.py

@@ -0,0 +1,39 @@
+#!/usr/bin/env python
+# coding=utf-8
+'''
+@Author: John
+@Email: johnjim0816@gmail.com
+@Date: 2020-06-11 20:58:59
+@LastEditor: John
+@LastEditTime: 2020-06-11 20:59:20
+@Discription: 
+@Environment: python 3.7.7
+'''
+import numpy as np
+
+class OUNoise(object):
+    def __init__(self, action_space, mu=0.0, theta=0.15, max_sigma=0.3, min_sigma=0.3, decay_period=100000):
+        self.mu           = mu
+        self.theta        = theta
+        self.sigma        = max_sigma
+        self.max_sigma    = max_sigma
+        self.min_sigma    = min_sigma
+        self.decay_period = decay_period
+        self.n_actions   = action_space.shape[0]
+        self.low          = action_space.low
+        self.high         = action_space.high
+        self.reset()
+        
+    def reset(self):
+        self.obs = np.ones(self.n_actions) * self.mu
+        
+    def evolve_obs(self):
+        x  = self.obs
+        dx = self.theta * (self.mu - x) + self.sigma * np.random.randn(self.n_actions)
+        self.obs = x + dx
+        return self.obs
+    
+    def get_action(self, action, t=0):
+        ou_obs = self.evolve_obs()
+        self.sigma = self.max_sigma - (self.max_sigma - self.min_sigma) * min(1.0, t / self.decay_period)
+        return np.clip(action + ou_obs, self.low, self.high)