UPDATE_NOTES.md

Update notes

This file records all major updates and new features, starting from version 0.5. As Tensorforce is still developing, updates and bug fixes for the internal architecture are continuously being implemented, which will not be tracked here in detail.

Latest changes

Agents:

• New agent argument tracking and corresponding function tracked_tensors() to track and retrieve the current value of predefined tensors, similar to summarizer for TensorBoard summaries
• New experimental value trace_decay and gae_decay for Tensorforce agent argument reward_estimation, soon for other agent types as well
• New options "early" and "late" for value estimate_advantage of Tensorforce agent argument reward_estimation
• Changed default value for Agent.act() argument deterministic from False to True

Layers:

• New option for Function layer argument function to pass string function expression with argument "x", e.g. "(x+1.0)/2.0"

Summarizer:

• New summary episode-length recorded as part of summary label "reward"

Environments:

• Support for vectorized parallel environments via new function Environment.is_vectorizable() and new argument num_parallel for Environment.reset()
  • See tensorforce/environments.cartpole.py for a vectorizable environment example
  • Runner uses vectorized parallelism by default if num_parallel > 1, remote=None and environment supports vectorization
  • See examples/act_observe_vectorized.py for more details on act-observe interaction
• New extended and vectorizable custom CartPole environment via key custom_cartpole (work in progress)
• New environment argument reward_shaping to provide a simple way to modify/shape rewards of an environment, can be specified either as callable or string function expression

run.py script:

• New option for command line arguments --checkpoints and --summaries to add comma-separated checkpoint/summary filename in addition to directory
• Added episode lengths to logging plot besides episode returns

Buxfixes:

• Temporal horizon handling of RNN layers
• Critical bugfix for late horizon value prediction (including DQN variants and DPG agent) in combination with baseline RNN
• GPU problems with scatter operations

---

Version 0.6.2

Buxfixes:

• Critical bugfix for DQN variants and DPG agent

---

Version 0.6.1

Agents:

• Removed default value "adam" for Tensorforce agent argument optimizer (since default optimizer argument learning_rate removed, see below)
• Removed option "minimum" for Tensorforce agent argument memory, use None instead
• Changed default value for dqn/double_dqn/dueling_dqn agent argument huber_loss from 0.0 to None

Layers:

• Removed default value 0.999 for exponential_normalization layer argument decay
• Added new layer batch_normalization (generally should only be used for the agent arguments reward_processing[return_processing] and reward_processing[advantage_processing])
• Added exponential/instance_normalization layer argument only_mean with default False
• Added exponential/instance_normalization layer argument min_variance with default 1e-4

Optimizers:

• Removed default value 1e-3 for optimizer argument learning_rate
• Changed default value for optimizer argument gradient_norm_clipping from 1.0 to None (no gradient clipping)
• Added new optimizer doublecheck_step and corresponding argument doublecheck_update for optimizer wrapper
• Removed linesearch_step optimizer argument accept_ratio
• Removed natural_gradient optimizer argument return_improvement_estimate

Saver:

• Added option to specify agent argument saver as string, which is interpreted as saver[directory] with otherwise default values
• Added default value for agent argument saver[frequency] as 10 (save model every 10 updates by default)
• Changed default value of agent argument saver[max_checkpoints] from 5 to 10

Summarizer:

• Added option to specify agent argument summarizer as string, which is interpreted as summarizer[directory] with otherwise default values
• Renamed option of agent argument summarizer from summarizer[labels] to summarizer[summaries] (use of the term "label" due to earlier version, outdated and confusing by now)
• Changed interpretation of agent argument summarizer[summaries] = "all" to include only numerical summaries, so all summaries except "graph"
• Changed default value of agent argument summarizer[summaries] from ["graph"] to "all"
• Changed default value of agent argument summarizer[max_summaries] from 5 to 7 (number of different colors in TensorBoard)
• Added option summarizer[filename] to agent argument summarizer

Recorder:

• Added option to specify agent argument recorder as string, which is interpreted as recorder[directory] with otherwise default values

run.py script:

• Added --checkpoints/--summaries/--recordings command line argument to enable saver/summarizer/recorder agent argument specification separate from core agent configuration

Examples:

• Added save_load_agent.py example script to illustrate regular agent saving and loading

Buxfixes:

• Fixed problem with optimizer argument gradient_norm_clipping not being applied correctly
• Fixed problem with exponential_normalization layer not updating moving mean and variance correctly
• Fixed problem with recent memory for timestep-based updates sometimes sampling invalid memory indices

---

Version 0.6

• Removed agent arguments execution, buffer_observe, seed
• Renamed agent arguments baseline_policy/baseline_network/critic_network to baseline/critic
• Renamed agent reward_estimation arguments estimate_horizon to predict_horizon_values, estimate_actions to predict_action_values, estimate_terminal to predict_terminal_values
• Renamed agent argument preprocessing to state_preprocessing
• Default agent preprocessing linear_normalization
• Moved agent arguments for reward/return/advantage processing from preprocessing to reward_preprocessing and reward_estimation[return_/advantage_processing]
• New agent argument config with values buffer_observe, enable_int_action_masking, seed
• Renamed PPO/TRPO/DPG argument critic_network/_optimizer to baseline/baseline_optimizer
• Renamed PPO argument optimization_steps to multi_step
• New TRPO argument subsampling_fraction
• Changed agent argument use_beta_distribution default to false
• Added double DQN agent (double_dqn)
• Removed Agent.act() argument evaluation
• Removed agent function arguments query (functionality removed)
• Agent saver functionality changed (Checkpoint/SavedModel instead of Saver/Protobuf): save/load functions and saver argument changed
• Default behavior when specifying saver is not to load agent, unless agent is created via Agent.load
• Agent summarizer functionality changed: summarizer argument changed, some summary labels and other options removed
• Renamed RNN layers internal_{rnn/lstm/gru} to rnn/lstm/gru and rnn/lstm/gru to input_{rnn/lstm/gru}
• Renamed auto network argument internal_rnn to rnn
• Renamed (internal_)rnn/lstm/gru layer argument length to horizon
• Renamed update_modifier_wrapper to optimizer_wrapper
• Renamed optimizing_step to linesearch_step, and UpdateModifierWrapper argument optimizing_iterations to linesearch_iterations
• Optimizer subsampling_step accepts both absolute (int) and relative (float) fractions
• Objective policy_gradient argument ratio_based renamed to importance_sampling
• Added objectives state_value and action_value
• Added Gaussian distribution arguments global_stddev and bounded_transform (for improved bounded action space handling)
• Changed default memory device argument to CPU:0
• Renamed rewards summaries
• Agent.create() accepts act-function as agent argument for recording
• Singleton states and actions are now consistently handled as singletons
• Major change to policy handling and defaults, in particular parametrized_distributions, new default policies parametrized_state/action_value
• Combined long and int type
• Always wrap environment in EnvironmentWrapper class
• Changed tune.py arguments

---

Version 0.5.5

• Changed independent mode of agent.act to use final values of dynamic hyperparameters and avoid TensorFlow conditions
• Extended "tensorflow" format of agent.save to include an optimized Protobuf model with an act-only graph as .pb file, and Agent.load format "pb-actonly" to load act-only agent based on Protobuf model
• Support for custom summaries via new summarizer argument value custom to specify summary type, and Agent.summarize(...) to record summary values
• Added min/max-bounds for dynamic hyperparameters min/max-bounds to assert valid range and infer other arguments
• Argument batch_size now mandatory for all agent classes
• Removed Estimator argument capacity, now always automatically inferred
• Internal changes related to agent arguments memory, update and reward_estimation
• Changed the default bias and activation argument of some layers
• Fixed issues with sequence preprocessor
• DQN and dueling DQN properly constrained to int actions only
• Added use_beta_distribution argument with default True to many agents and ParametrizedDistributions policy, so default can be changed

---

Version 0.5.4

• DQN/DuelingDQN/DPG argument memory now required to be specified explicitly, plus update_frequency default changed
• Removed (temporarily) conv1d/conv2d_transpose layers due to TensorFlow gradient problems
• Agent, Environment and Runner can now be imported via from tensorforce import ...
• New generic reshape layer available as reshape
• Support for batched version of Agent.act and Agent.observe
• Support for parallelized remote environments based on Python's multiprocessing and socket (replacing tensorforce/contrib/socket_remote_env/ and tensorforce/environments/environment_process_wrapper.py), available via Environment.create(...), Runner(...) and run.py
• Removed ParallelRunner and merged functionality with Runner
• Changed run.py arguments
• Changed independent mode for Agent.act: additional argument internals and corresponding return value, initial internals via Agent.initial_internals(), Agent.reset() not required anymore
• Removed deterministic argument for Agent.act unless independent mode
• Added format argument to save/load/restore with supported formats tensorflow, numpy and hdf5
• Changed save argument append_timestep to append with default None (instead of 'timesteps')
• Added get_variable and assign_variable agent functions

---

Version 0.5.3

• Added optional memory argument to various agents
• Improved summary labels, particularly "entropy" and "kl-divergence"
• linear layer now accepts tensors of rank 1 to 3
• Network output / distribution input does not need to be a vector anymore
• Transposed convolution layers (conv1d/2d_transpose)
• Parallel execution functionality contributed by @jerabaul29, currently under tensorforce/contrib/
• Accept string for runner save_best_agent argument to specify best model directory different from saver configuration
• saver argument steps removed and seconds renamed to frequency
• Moved Parallel/Runner argument max_episode_timesteps from run(...) to constructor
• New Environment.create(...) argument max_episode_timesteps
• TensorFlow 2.0 support
• Improved Tensorboard summaries recording
• Summary labels graph, variables and variables-histogram temporarily not working
• TF-optimizers updated to TensorFlow 2.0 Keras optimizers
• Added TensorFlow Addons dependency, and support for TFA optimizers
• Changed unit of target_sync_frequency from timesteps to updates for dqn and dueling_dqn agent

---

Version 0.5.2

• Improved unittest performance
• Added updates and renamed timesteps/episodes counter for agents and runners
• Renamed critic_{network,optimizer} argument to baseline_{network,optimizer}
• Added Actor-Critic (ac), Advantage Actor-Critic (a2c) and Dueling DQN (dueling_dqn) agents
• Improved "same" baseline optimizer mode and added optional weight specification
• Reuse layer now global for parameter sharing across modules
• New block layer type (block) for easier sharing of layer blocks
• Renamed PolicyAgent/-Model to TensorforceAgent/-Model
• New Agent.load(...) function, saving includes agent specification
• Removed PolicyAgent argument (baseline-)network
• Added policy argument temperature
• Removed "same" and "equal" options for baseline_* arguments and changed internal baseline handling
• Combined state/action_value to value objective with argument value either "state" or "action"

---

Version 0.5.1

• Fixed setup.py packages value

---

Version 0.5.0

Agent:

• DQFDAgent removed (temporarily)
• DQNNstepAgent and NAFAgent part of DQNAgent
• Agents need to be initialized via agent.initialize() before application
• States/actions of type int require an entry num_values (instead of num_actions)
• Agent.from_spec() changed and renamed to Agent.create()
• Agent.act() argument fetch_tensors changed and renamed to query, index renamed to parallel, buffered removed
• Agent.observe() argument index renamed to parallel
• Agent.atomic_observe() removed
• Agent.save/restore_model() renamed to Agent.save/restore()

Agent arguments:

• update_mode renamed to update
• states_preprocessing and reward_preprocessing changed and combined to preprocessing
• actions_exploration changed and renamed to exploration
• execution entry num_parallel replaced by a separate argument parallel_interactions
• batched_observe and batching_capacity replaced by argument buffer_observe
• scope renamed to name

DQNAgent arguments:

• update_mode replaced by batch_size, update_frequency and start_updating
• optimizer removed, implicitly defined as 'adam', learning_rate added
• memory defines capacity of implicitly defined memory 'replay'
• double_q_model removed (temporarily)

Policy gradient agent arguments:

• New mandatory argument max_episode_timesteps
• update_mode replaced by batch_size and update_frequency
• memory removed
• baseline_mode removed
• baseline argument changed and renamed to critic_network
• baseline_optimizer renamed to critic_optimizer
• gae_lambda removed (temporarily)

PPOAgent arguments:

• step_optimizer removed, implicitly defined as 'adam', learning_rate added

TRPOAgent arguments:

• cg_* and ls_* arguments removed

VPGAgent arguments:

• optimizer removed, implicitly defined as 'adam', learning_rate added

Environment:

• Environment properties states and actions are now functions states() and actions()
• States/actions of type int require an entry num_values (instead of num_actions)
• New function Environment.max_episode_timesteps()

Contrib environments:

• ALE, MazeExp, OpenSim, Gym, Retro, PyGame and ViZDoom moved to tensorforce.environments
• Other environment implementations removed (may be upgraded in the future)

Runners:

• Improved run() API for Runner and ParallelRunner
• ThreadedRunner removed

Other:

• examples folder (including configs) removed, apart from quickstart.py
• New benchmarks folder to replace parts of old examples folder