add back sonnet dependency. If sonnet is not installed, fall back to simpleAgent that does not need sonnet.

examples/pybullet/gym/agents/simpleAgent.py

@@ -0,0 +1,37 @@
+"""Loads a DDPG agent without too much external dependencies
+"""
+from __future__ import absolute_import
+from __future__ import division
+from __future__ import print_function
+
+import os
+import collections
+import numpy as np
+import tensorflow as tf
+import pdb
+
+class SimpleAgent():
+  def __init__(
+      self,
+      session,
+      ckpt_path,
+      actor_layer_size,
+      observation_dim=31
+  ):
+    self._ckpt_path = ckpt_path
+    self._session = session
+    self._observation_dim = observation_dim
+    self._build()
+
+  def _build(self):
+    saver = tf.train.import_meta_graph(self._ckpt_path + '.meta')
+    saver.restore(
+        sess=self._session,
+        save_path=self._ckpt_path)
+    self._action = tf.get_collection('action_op')[0]
+    self._obs = tf.get_collection('observation_placeholder')[0]
+
+  def __call__(self, observation):
+    feed_dict={self._obs: observation}
+    out_action = self._session.run(self._action, feed_dict=feed_dict)
+    return out_action[0]