add ARS to train/eval Minitaur

examples/pybullet/gym/pybullet_envs/ARS/shared_noise.py

@@ -0,0 +1,41 @@
+"""TODO(jietan): DO NOT SUBMIT without one-line documentation for shared_noise.
+Code in this file is copied and adapted from
+https://github.com/ray-project/ray/tree/master/python/ray/rllib/es
+TODO(jietan): DO NOT SUBMIT without a detailed description of shared_noise.
+"""
+
+from __future__ import absolute_import
+from __future__ import division
+from __future__ import print_function
+import numpy as np
+
+
+def create_shared_noise():
+    """
+    Create a large array of noise to be shared by all workers. Used
+    for avoiding the communication of the random perturbations delta.
+    """
+
+    seed = 12345
+    count = 250000000
+    noise = np.random.RandomState(seed).randn(count).astype(np.float64)
+    return noise
+
+
+class SharedNoiseTable(object):
+    def __init__(self, noise, seed = 11):
+
+        self.rg = np.random.RandomState(seed)
+        self.noise = noise
+        assert self.noise.dtype == np.float64
+
+    def get(self, i, dim):
+        return self.noise[i:i + dim]
+
+    def sample_index(self, dim):
+        return self.rg.randint(0, len(self.noise) - dim + 1)
+
+    def get_delta(self, dim):
+        idx = self.sample_index(dim)
+        return idx, self.get(idx, dim)
+