def __init__(self,
dU,
obs_tensor,
act_op,
feat_op,
var,
sess,
device_string,
copy_param_scope=None):
Policy.__init__(self)
self.dU = dU
self.obs_tensor = obs_tensor
self.act_op = act_op
self.feat_op = feat_op
self.sess = sess
self.device_string = device_string
self.chol_pol_covar = np.diag(np.sqrt(var))
self.scale = None # must be set from elsewhere based on observations
self.bias = None
self.x_idx = None
if copy_param_scope:
self.copy_params = tf.get_collection(tf.GraphKeys.VARIABLES,
scope=copy_param_scope)
self.copy_params_assign_placeholders = [
tf.placeholder(tf.float32, shape=param.get_shape())
for param in self.copy_params
]
self.copy_params_assign_ops = [
tf.assign(self.copy_params[i],
self.copy_params_assign_placeholders[i])
for i in range(len(self.copy_params))
]
def get_variables(self):
return tf.get_collection(tf.GraphKeys.GLOBAL_VARIABLES, self.scope)
def get_trainable_variables(self):
return tf.get_collection(tf.GraphKeys.TRAINABLE_VARIABLES, self.scope)
def _global_vars(self, scope):
res = tf.get_collection(tf.GraphKeys.GLOBAL_VARIABLES, scope=self.scope + '/' + scope)
return res
def _vars(self, scope):
res = tf.get_collection(tf.GraphKeys.TRAINABLE_VARIABLES, scope=self.scope + '/' + scope)
assert len(res) > 0
return res
def trainable_vars(self):
return tf.get_collection(tf.GraphKeys.TRAINABLE_VARIABLES,
scope=self.name)
def vars(self):
return tf.get_collection(tf.GraphKeys.GLOBAL_VARIABLES,
scope=self.name)
def __init__(self, *, policy, ob_space, ac_space, nbatch_act, nbatch_train,
nsteps, ent_coef, vf_coef, max_grad_norm):
sess = get_session()
with tf.variable_scope('ppo2_model', reuse=tf.AUTO_REUSE):
# CREATE OUR TWO MODELS
# act_model that is used for sampling
act_model = policy(nbatch_act, 1, sess)
# Train model for training
train_model = policy(nbatch_train, nsteps, sess)
# CREATE THE PLACEHOLDERS
A = train_model.pdtype.sample_placeholder([None])
ADV = tf.placeholder(tf.float32, [None])
R = tf.placeholder(tf.float32, [None])
# Keep track of old actor
OLDNEGLOGPAC = tf.placeholder(tf.float32, [None])
# Keep track of old critic
OLDVPRED = tf.placeholder(tf.float32, [None])
LR = tf.placeholder(tf.float32, [])
# Cliprange
CLIPRANGE = tf.placeholder(tf.float32, [])
neglogpac = train_model.pd.neglogp(A)
# Calculate the entropy
# Entropy is used to improve exploration by limiting the premature convergence to suboptimal policy.
entropy = tf.reduce_mean(train_model.pd.entropy())
# CALCULATE THE LOSS
# Total loss = Policy gradient loss - entropy * entropy coefficient + Value coefficient * value loss
# Clip the value to reduce variability during Critic training
# Get the predicted value
vpred = train_model.vf
vpredclipped = OLDVPRED + tf.clip_by_value(train_model.vf - OLDVPRED, - CLIPRANGE, CLIPRANGE)
# Unclipped value
vf_losses1 = tf.square(vpred - R)
# Clipped value
vf_losses2 = tf.square(vpredclipped - R)
vf_loss = .5 * tf.reduce_mean(tf.maximum(vf_losses1, vf_losses2))
# Calculate ratio (pi current policy / pi old policy)
ratio = tf.exp(OLDNEGLOGPAC - neglogpac)
# Defining Loss = - J is equivalent to max J
pg_losses = -ADV * ratio
pg_losses2 = -ADV * tf.clip_by_value(ratio, 1.0 - CLIPRANGE, 1.0 + CLIPRANGE)
# Final PG loss
pg_loss = tf.reduce_mean(tf.maximum(pg_losses, pg_losses2))
approxkl = .5 * tf.reduce_mean(tf.square(neglogpac - OLDNEGLOGPAC))
clipfrac = tf.reduce_mean(tf.to_float(tf.greater(tf.abs(ratio - 1.0), CLIPRANGE)))
# Total loss
loss = pg_loss - entropy * ent_coef + vf_loss * vf_coef
# UPDATE THE PARAMETERS USING LOSS
# 1. Get the model parameters
params = tf.trainable_variables('ppo2_model')
# 2. Build our trainer
trainer = MpiAdamOptimizer(MPI.COMM_WORLD, learning_rate=LR, epsilon=1e-5)
# 3. Calculate the gradients
grads_and_var = trainer.compute_gradients(loss, params)
grads, var = zip(*grads_and_var)
if max_grad_norm is not None:
# Clip the gradients (normalize)
grads, _grad_norm = tf.clip_by_global_norm(grads, max_grad_norm)
grads_and_var = list(zip(grads, var))
# zip aggregate each gradient with parameters associated
# For instance zip(ABCD, xyza) => Ax, By, Cz, Da
_train = trainer.apply_gradients(grads_and_var)
def train(lr, cliprange, obs, returns, masks, actions, values, neglogpacs, states=None):
# Here we calculate advantage A(s,a) = R + yV(s') - V(s)
# Returns = R + yV(s')
advs = returns - values
# Normalize the advantages
advs = (advs - advs.mean()) / (advs.std() + 1e-8)
td_map = {train_model.X:obs, A:actions, ADV:advs, R:returns, LR:lr,
CLIPRANGE:cliprange, OLDNEGLOGPAC:neglogpacs, OLDVPRED:values}
if states is not None:
td_map[train_model.S] = states
td_map[train_model.M] = masks
return sess.run(
[pg_loss, vf_loss, entropy, approxkl, clipfrac, _train],
td_map
)[:-1]
self.loss_names = ['policy_loss', 'value_loss', 'policy_entropy', 'approxkl', 'clipfrac']
self.train = train
self.train_model = train_model
self.act_model = act_model
self.step = act_model.step
self.value = act_model.value
self.initial_state = act_model.initial_state
self.save = functools.partial(save_variables, sess=sess)
self.load = functools.partial(load_variables, sess=sess)
if MPI.COMM_WORLD.Get_rank() == 0:
initialize()
global_variables = tf.get_collection(tf.GraphKeys.GLOBAL_VARIABLES, scope="")
sync_from_root(sess, global_variables) #pylint: disable=E1101
