Evaluating Lossy Compression Rates of Deep Generative Models

The code accompanying the ICML paper: Evaluating Lossy Compression Rates of Deep Generative Models. This repo is released as it is, and will not be maintained in the future.

Authors: Sicong Huang*, Alireza Makhzani*, Yanshuai Cao , Roger Grosse (*Equal contribution)

Citing this work

@article{huang2020rd,
  title={Evaluating Lossy Compression Rates of Deep Generative Models},
  author={Huang, Sicong and Makhzani, Alireza and Cao, Yanshuai and Grosse, Roger},
  booktitle = {ICML},
  year={2020}
}

Running this code

Dependencies are listed in requirement.txt. Lite tracer can be found here.

There are only 2 argparse arguments:

• hparam_set: (str) This is label of the experiment, and it point to a set of hyper parameters associated with this experiment, organzied by an Hparam object. They are registered under rate_distortion/hparams.
• e_name: (str) "Extra name". Used to add an extra suffix after the hparam_set in the name of the experiment. This is used to run another copy (for testing purposes for example) of the experiment defined by hparam_set without having to create the same hparam_set.

The configuration for each experiment is defined by an Hparam object registered in rate_distortion/hparams. The default value for an undefined field is None. The Hparam object is hierarchical and compositional for modularity.

This codebase has a self-contained system for keeping track of checkpoints and outputs based on the Hparam object. To load checkpoint from another experiment registered in the codebase, assign load_hparam_name to the name of a registered hparam_set in the codebase. If the model you want to test is not trained with this codebase, to load your model, you can simply set specific_model_path to the path of your decoder weights.

Reproducing our results.

• Set the paths.

  Make sure to properly set all the directories and paths accordingly, including the output directories output_root_dir, the data directory data_dir and the checkpoint directory checkpoint_root_dir in the rate_distortion/hparams/defaults.py. Note that the datasets (MNIST and CIFAR10) will be automatically downloaded if you don't have then in the data_dir the already. For all the sbatch files, make sure to set the working directory accordingly (to where this repo is cloned) in each command as well.

• Get the checkpoints.

  The training code and script for VAEs are included, for the rest of the models, trained checkpoints can be found here. Set the FILEPATH (it should end with .zip) and run this command to download the checkpoints zip:

  wget --load-cookies /tmp/cookies.txt "https://docs.google.com/uc?export=download&confirm=$(wget --quiet --save-cookies /tmp/cookies.txt --keep-session-cookies --no-check-certificate 'https://docs.google.com/uc?export=download&id=1KyIGHCIDl4DDRBLBcaBg39adsMn4xAev' -O- | sed -rn 's/.*confirm=([0-9A-Za-z_]+).*/\1\n/p')&id=1KyIGHCIDl4DDRBLBcaBg39adsMn4xAev" -O FILEPATH && rm -rf /tmp/cookies.txt
  

  And then unzip it into the checkpoint_root_dir

  unzip FILEPATH -d checkpoint_root_dir
  

• Two rounds of AIS runs.

  To conform to mathematical correctness when tuning the HMC step sizes, for each setting there are two round of experiments. During the first round, step sizes of HMC are adaptively tuned and saved. During the second round, step sizes are loaded and the rate distortion curve (or BDMC gap) was computed with another random seed.

  All experiments used in the paper can be found inside rate_distortion/hparams, and you can reproduce all experiments by running the sbatch files in a particular order. The ordering is important because there are dependencies between different runs. The first round of HMC step-size tuning experiments must be finished before the second round of runs can load step sizes.

• First round
  All .sh files are sbatch files in rate_distortion/hparams and to run them, simply

  sbatch FILENAME.sh
  

  Notice that if you don't already have the datasets downloaded, running multiple runs concurrently might cause interference of the data loading/downloading processes. So a good practice is to let the data downloading process finish before starting another runs related to the same dataset. This is taken care of by the following sbatch files and again it's important to wait for one to finish before starting the next. First run analytical.sh which download MNIST and train a linear VAE. You can also use this to check whether everything is set up properly. Then run train_models.sh to train the VAEs, and then run first_round.sh, and this will reproduce the first round of experiments where HMC step sizes are adaptively tuned. Same with BDMC gaps, run bdmc_first_round.sh.

• Second round
  After the first round is finished, run second_round.sh and it will load the saved step sizes and run the experiments again with another random seed. For BDMC, run bdmc_second_round.sh. If there's a "rerun" in the name of any experiment, it indicates that it's in this group.

• Baseline
  Run baseline.sh.

• Plots
  Set the output_root_dir in rate_distortion/plots/icml_plots.py to be the same as the output_root_dir in rate_distortion/hparams/defaults.py which was set in the beginning. Then run icml_plots.sh.

Test your own generative models.

The codebase is also modularized for testing your own decoder-based generative models. You need to register your model under rate_distortion/models/user_models, and register the Hparam object at rate_distortion/hparams/user_models. Your model should come with its decoder variance model.x_logvar as a scalar or vector tensor. Set specific_model_path to the path of your decoder weights.

PyTorch:

If the generative models is trained in PyTorch, the checkpoint should contain the key "state_dict" as the weights of the model.

Others:

If the generative models is trained in other frameworks, you'll need to manually bridge and load the weights. For example, the AAEs were trained in tensorflow, with the weights saved as numpy, and then loaded as nn.Parameter in PyTorch. Refer torate_distortion/utils/aad_utils for more details.

Detailed Experimental Settings

More details on how to control experimental settings can be found below.

General configuration:

• specific_model_path: (str) Set to the path to the decoder weights for your own experiments. Set to None if you are reproducing our experiments.
• original_experiment: (boolean) This should be set to True when the checkpoint or the model is from the paper. When you are testing your own generative model, set this False and it will load from specific_model_path instead of the directories generated by this codebase. You may need to customize the load_user_model function in rate_distortion/utils/experiment_utils.py for your own generative model.
• output_root_dir: (str) The root dir for the experiment workspace. Experiment results, checkpoints will be saved in subfolders under this directory.
• group_list: (list) A list specifying the file tree structure for the output of this experiment, inside the output_root_dir.
• step_sizes_target: (str) When not defined or set to None, HMC step sizes adaptively tunned and saved during AIS. When specified as the name of hparam_set of another previously finished experiment, HMC step sizes will be loaded from that experiment.
• train_first: (boolean) If set to true, experiment will first run training algorithm, and then run RD evaluation. Otherwise only RD evaluation will be run.
• model_name: (str) The name of the model you want to use. The model must be registered under rate_distortion/models.

Sub-hparams:

• model_train contains information about the original training setting of the model. (In this code base only VAE training is supported)
• rd: contains information about the AIS setting for the rate distortion curve.
• dataset: contains information about the dataset. Set mnist() for MNIST and cifar() for CIFAR10.

rd sub-Hparam:

• rd_data_list: (list) The list of data to be used. Can include only test, or both test and train.
• n_chains: (int) The number of independent AIS chains per data point.
• anneal_steps: (int) The number of annealing steps(intermediate distributions) for AIS. Note that this is not the total steps yet. Total step will also include the patched intermediate distributions as described in the paper.
• temp_schedule: (str) Temperature schedule. Just use "sigmoid".
• leap_steps: (int) Number of leap frog steps for HMC.
• acceptance_prob: (float) Average acceptance probability for adaptive step size tuning in HMC.
• batch_size: (int) Batch size for RD AIS. Empirically 50 and 400 do not differ much.
• target_dist: (str) Target distribution for AIS. Use "joint_xz" for normal prior and use "mix_prior" for mixture of prior experiment.
• max_beta: (float) The maximum beta value on the curve.
• num_betas: (int) How many beta to compute Rate Distortion. How many points on the RD curve.

model_train sub-Hparam:

• z_size: (int) Size of the latent code.
• batch_size: (int) The batch size for training.
• epochs: (int) The number of epochs to train.
• x_var: (float) Initial decoder variance.

dataset sub-Hparam

• data_name: (str) The name of the dataset to be used.
• train_loader: (str) The name of the training loader to be used.
• eval_train_loader: (str) The loader for "train" in the rd_data_list.
• eval_test_loader: (str) The loader for "test" in the rd_data_list.
• input_dims: (list) A list specifying the input dimensions.
• input_vector_length: (int) The product of input_dims.

The rest: normally the below settings do not need to be changed.

• cuda: (boolean) Whether or not to use CUDA.
• verbose: (boolean) Verbose or not for logging and print statements.
• random_seed: (int) Random seed.
• rd: Set to default_rd()
• monitor_hmc: (boolean) Set to True to monitor the stability of HMC. Warnings will be given if the average acceptance probability goes below 60%.
• n_test_batch: (int) Number of batch you want to test on during training or IWAE. During training it'll test on a held-out validation set.
• mixture_weight: (int) The mixture weight for the bad prior in the mixture of prior experiment
• bad_std: (int) The standard deviation of the Gaussian in the bad prior