Neural Pipeline Search (NePS)

Welcome to NePS, a powerful and flexible Python library for hyperparameter optimization (HPO) and neural architecture search (NAS) with its primary goal: enable HPO adoption in practice for deep learners!

NePS houses recently published and some more well-established algorithms that are all capable of being run massively parallel on any distributed setup, with tools to analyze runs, restart runs, etc.

Key Features

In addition to the common features offered by traditional HPO and NAS libraries, NePS stands out with the following key features:

1. Hyperparameter Optimization (HPO) With Prior Knowledge:

   • NePS excels in efficiently tuning hyperparameters using algorithms that enable users to make use of their prior knowledge within the search space. This is leveraged by the insights presented in:
     • PriorBand: Practical Hyperparameter Optimization in the Age of Deep Learning
     • πBO: Augmenting Acquisition Functions with User Beliefs for Bayesian Optimization

2. Neural Architecture Search (NAS) With Context-free Grammar Search Spaces:

   • NePS is equipped to handle context-free grammar search spaces, providing advanced capabilities for designing and optimizing architectures. this is leveraged by the insights presented in:
     • Construction of Hierarchical Neural Architecture Search Spaces based on Context-free Grammars

3. Easy Parallelization and Resumption of Runs:

   • NePS simplifies the process of parallelizing optimization tasks both on individual computers and in distributed computing environments. It also allows users to conveniently resume these optimization tasks after completion to ensure a seamless and efficient workflow for long-running experiments.

4. Seamless User Code Integration:

   • NePS's modular design ensures flexibility and extensibility. Integrate NePS effortlessly into existing machine learning workflows.

Tip

Check out:

• Reference documentation for a quick overview.
• API for a more detailed reference.
• Examples for copy-pastable code to get started.

Getting Started

1. Installation

NePS requires Python 3.8 or higher. You can install it via pip or from source.

Using pip:

pip install neural-pipeline-search

Note: As indicated with the v0.x.x version number, NePS is early stage code and APIs might change in the future.

You can install from source by cloning the repository and running:

git clone git@github.com:automl/neps.git
cd neps
poetry install

2. Basic Usage

Using neps always follows the same pattern:

1. Define a run_pipeline function capable of evaluating different architectural and/or hyperparameter configurations for your problem.
2. Define a search space named pipeline_space of those Parameters e.g. via a dictionary
3. Call neps.run to optimize run_pipeline over pipeline_space

In code, the usage pattern can look like this:

import neps
import logging


# 1. Define a function that accepts hyperparameters and computes the validation error
def run_pipeline(
    hyperparameter_a: float, hyperparameter_b: int, architecture_parameter: str
) -> dict:
    # Create your model
    model = MyModel(architecture_parameter)

    # Train and evaluate the model with your training pipeline
    validation_error, training_error = train_and_eval(
        model, hyperparameter_a, hyperparameter_b
    )

    return {  # dict or float(validation error)
        "loss": validation_error,
        "info_dict": {
            "training_error": training_error
            # + Other metrics
        },
    }


# 2. Define a search space of parameters; use the same names for the parameters as in run_pipeline
pipeline_space = dict(
    hyperparameter_b=neps.IntegerParameter(
        lower=1, upper=42, is_fidelity=True
    ),  # Mark 'is_fidelity' as true for a multi-fidelity approach.
    hyperparameter_a=neps.FloatParameter(
        lower=0.001, upper=0.1, log=True
    ),  # If True, the search space is sampled in log space.
    architecture_parameter=neps.CategoricalParameter(
        ["option_a", "option_b", "option_c"]
    ),
)

if __name__ == "__main__":
    # 3. Run the NePS optimization
    logging.basicConfig(level=logging.INFO)
    neps.run(
        run_pipeline=run_pipeline,
        pipeline_space=pipeline_space,
        root_directory="path/to/save/results",  # Replace with the actual path.
        max_evaluations_total=100,
        searcher="hyperband"  # Optional specifies the search strategy,
        # otherwise NePs decides based on your data.
    )

Examples

Discover how NePS works through these practical examples:

• Pipeline Space via YAML: Explore how to define the pipeline_space using a YAML file instead of a dictionary.

• Hyperparameter Optimization (HPO): Learn the essentials of hyperparameter optimization with NePS.

• Architecture Search with Primitives: Dive into architecture search using primitives in NePS.

• Multi-Fidelity Optimization: Understand how to leverage multi-fidelity optimization for efficient model tuning.

• Utilizing Expert Priors for Hyperparameters: Learn how to incorporate expert priors for more efficient hyperparameter selection.

• Additional NePS Examples: Explore more examples, including various use cases and advanced configurations in NePS.

Citations

Please consider citing us if you use our tool!

Refer to our documentation on citations