Resume mode, Plotly and PyTorch update, OnPolicyCrossEntropy memory

Resume mode

• #455 adds train@ resume mode and refactors the enjoy mode. See PR for detailed info.

train@ usage example

Specify train mode as train@{predir}, where {predir} is the data directory of the last training run, or simply use latest` to use the latest. e.g.:

python run_lab.py slm_lab/spec/benchmark/reinforce/reinforce_cartpole.json reinforce_cartpole train
# terminate run before its completion
# optionally edit the spec file in a past-future-consistent manner

# run resume with either of the commands:
python run_lab.py slm_lab/spec/benchmark/reinforce/reinforce_cartpole.json reinforce_cartpole train@latest
# or to use a specific run folder
python run_lab.py slm_lab/spec/benchmark/reinforce/reinforce_cartpole.json reinforce_cartpole train@data/reinforce_cartpole_2020_04_13_232521

enjoy mode refactor

The train@ resume mode API allows for the enjoy mode to be refactored. Both share similar syntax. Continuing with the example above, to enjoy a train model, we now use:

python run_lab.py slm_lab/spec/benchmark/reinforce/reinforce_cartpole.json reinforce_cartpole enjoy@data/reinforce_cartpole_2020_04_13_232521/reinforce_cartpole_t0_s0_spec.json

Plotly and PyTorch update

• #453 updates Plotly to 4.5.4 and PyTorch to 1.3.1.
• #454 explicitly shuts down Plotly orca server after plotting to prevent zombie processes

PPO batch size optimization

• #453 adds chunking to allow PPO to run on larger batch size by breaking up the forward loop.

New OnPolicyCrossEntropy memory

• #446 adds a new OnPolicyCrossEntropy memory class. See PR for details. Credits to @ingambe.