TRFL (pronounced "truffle") is a library built on top of TensorFlow that exposes several useful building blocks for implementing Reinforcement Learning agents.

TRFL can be installed from pip with the following command: pip install trfl

TRFL will work with both the CPU and GPU version of tensorflow, but to allow for that it does not list Tensorflow as a requirement, so you need to install Tensorflow and Tensorflow-probability separately if you haven't already done so.

import tensorflow as tf
import trfl
# Q-values for the previous and next timesteps, shape [batch_size, num_actions].
q_tm1 = tf.get_variable(
    "q_tm1", initializer=[[1., 1., 0.], [1., 2., 0.]], dtype=tf.float32)
q_t = tf.get_variable(
    "q_t", initializer=[[0., 1., 0.], [1., 2., 0.]], dtype=tf.float32)
# Action indices, discounts and rewards, shape [batch_size].
a_tm1 = tf.constant([0, 1], dtype=tf.int32)
r_t = tf.constant([1, 1], dtype=tf.float32)
pcont_t = tf.constant([0, 1], dtype=tf.float32)  # the discount factor
# Q-learning loss, and auxiliary data.
loss, q_learning = trfl.qlearning(q_tm1, a_tm1, r_t, pcont_t, q_t)

loss is the tensor representing the loss. For Q-learning, it is half the squared difference between the predicted Q-values and the TD targets, shape [batch_size]. Extra information is in the q_learning namedtuple, including q_learning.td_error and q_learning.target.

The loss tensor can be differentiated to derive the corresponding RL update.

reduced_loss = tf.reduce_mean(loss)
optimizer = tf.train.AdamOptimizer(learning_rate=0.1)
train_op = optimizer.minimize(reduced_loss)

All loss functions in the package return both a loss tensor and a namedtuple with extra information, using the above convention, but different functions may have different extra fields. Check the documentation of each function below for more information.

Check out the full documentation page here.