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A command line argument parsing utility using python class-based namespace for better IDE static auto-completion

Project description

  • 2019/12/09: Just finished my DeepMind Internship. Now params_proto contain a new proto implementation, and a complementary hyperparameter search library! See neo_proto and neo_hyper.
  • 2019/06/11: Now supports tab-completion at the command line!
  • 2018/11/08: Now supports both python 3.52 as well as 3.6! :bangbang::star:

What is “Experiment Parameter Hell”?

“Experiemnt Parameter Hell” occurs when you have more than twenty parameters for your ML project that are all defined as string/function parameters with click or argparse. Sometimes these parameters are defined in a launch script and passes through five layers of function calls during an experiment.

Your Python IDEs work very hard on static code-block analysis to intelligently make you more productive, and the “parameter hell” breaks all of that.

Step 1: Declarative Pattern to the Rescue!

For this reason, you want to avoid using dictionaries or opaque argparse definitions as much as possible. Instead, you want to write those declaratively, so that your IDE can actually help you navigate through those layers of function calls. The hyper-parameter library, params_proto makes this easy, by integrating python namespaces (a bare python class) with argparse, so that on the python side you get auto-completion, and from the command line you can pass in changes.


First let’s install params-proto and its supporting module waterbear

pip install params-proto waterbear

Then to declare your hyperparameters, you can write the following in a your_project/soft_ac/ file:

import sys
from params_proto.neo_proto import ParamsProto, Flag, Proto, PrefixProto

# this is the first config schema
class Args(PrefixProto):
    """Soft-actor Critic Implementation with SOTA Performance

    debug = True if "pydevd" in sys.modules else False

    cuda = Flag("cuda tend to be slower.")
    seed = 42
    env_name = "FetchReach-v1"
    n_workers = 1 if debug else 12
    v_lr = 1e-3
    pi_lr = 1e-3
    n_initial_rollouts = 0 if debug else 100
    n_test_rollouts = 15
    demo_length = 20
    clip_inputs = Flag()
    normalize_inputs = Flag()

# this is the second schema
class LfGR(PrefixProto):
    # reporting
    use_lfgr = True
    start = 0 if Args.debug else 10
    store_interval = 10
    visualization_interval = 10

Step 2: Sweeping Hyper-parameters :fire:

Then you an sweep the hyperparameter via the following declarative pattern:

from rl import main, Args
from params_proto.neo_hyper import Sweep

if __name__ == '__main__':
    from lp_analysis import instr

    with Sweep(Args, LfGR) as sweep:
    # override the default
        Args.pi_lr = 3e-3
        Args.clip_inputs = True # this was a flag

    # override the second config object
    LfGR.visualization_interval = 40

    # product between the zipped and the seed
        with sweep.product:
        # similar to python zip, unpacks a list of values.
                Args.env_name = ['FetchReach-v1', 'FetchPush-v1', 'FetchPickAndPlace-v1', 'FetchSlide-v1']
                Args.n_epochs = [4, 12, 12, 20]
                Args.n_workers = [5, 150, 200, 500]
        # the seed is sweeped at last
            Args.seed = [100, 200, 300, 400, 500, 600]

    for i, deps in sweep.items():
        thunk = instr(main, deps, _job_postfix=f"{Args.env_name}")

and it should print out a list of dictionaries that looks like:

{Args.pi_lr: 3e-3, Args.clip_inputs: True, LfGR.visualization_interval: 40, Args.env_name: "FetchReach-v1", ... Args.seed: 100}
{Args.pi_lr: 3e-3, Args.clip_inputs: True, LfGR.visualization_interval: 40, Args.env_name: "FetchReach-v1", ... Args.seed: 200}
{Args.pi_lr: 3e-3, Args.clip_inputs: True, LfGR.visualization_interval: 40, Args.env_name: "FetchReach-v1", ... Args.seed: 300}

## Where Can I find Documentation?

Look at the specification file at*.py , which is part of the integrated test. These scripts contains the most comprehensive set of usage patters!!

The new version has a neo_ prefix. We will deprecate the older (non-neo) version in a few month.

Writing documentation as uhm…, man page?

Params-Proto exposes your argument namespace’s doc string as the usage note. For users of your code-block, there is no better help than the one that comes with the script itself!

With params-proto, your help is only one -h away :)

And Your code-block becomes the documentation.

Tab-completion for your script!

params_proto uses argparse together with argcomplete, which enables command line autocomplete on tabs! To enable run

pip install params-proto
# then:

For details, see `argcomplete’s documentation <>`__.

Why Use Params_Proto Instead of Click or Argparse?

Because this declarative, singleton pattern allows you to:

Place all of the arguments under a namespace that can be statically checked.

so that your IDE can:

  1. Find usage of each argument
  2. jump from anywhere in your code-block base to the declaration of that argument
  3. refactor your argument name in the entire code-block base automatically

Params_proto is the declarative way to write command line arguments, and is the way to go for ML projects.

How to override when calling from python

It is very easy to over-ride the parameters when you call your function: have most of your training code-block directly reference the parser namespace (your configuration namespace really), and just monkey patch the attribute.

params-proto works very well with the clound ML launch tool jaynes. Take a look at the automagic awesomeness of jaynes:)

To Develop And Contribute

git clone
cd params_proto
make dev

To test, run the following under both python 3.52 and 3.6.

make test

This make dev command should build the wheel and install it in your current python environment. Take a look at the for details.

To publish, first update the version number, then do:

make publish

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