Book Image

Hyperparameter Tuning with Python

By : Louis Owen
Book Image

Hyperparameter Tuning with Python

By: Louis Owen

Overview of this book

Hyperparameters are an important element in building useful machine learning models. This book curates numerous hyperparameter tuning methods for Python, one of the most popular coding languages for machine learning. Alongside in-depth explanations of how each method works, you will use a decision map that can help you identify the best tuning method for your requirements. You’ll start with an introduction to hyperparameter tuning and understand why it's important. Next, you'll learn the best methods for hyperparameter tuning for a variety of use cases and specific algorithm types. This book will not only cover the usual grid or random search but also other powerful underdog methods. Individual chapters are also dedicated to the three main groups of hyperparameter tuning methods: exhaustive search, heuristic search, Bayesian optimization, and multi-fidelity optimization. Later, you will learn about top frameworks like Scikit, Hyperopt, Optuna, NNI, and DEAP to implement hyperparameter tuning. Finally, you will cover hyperparameters of popular algorithms and best practices that will help you efficiently tune your hyperparameter. By the end of this book, you will have the skills you need to take full control over your machine learning models and get the best models for the best results.
Table of Contents (19 chapters)
1
Section 1:The Methods
8
Section 2:The Implementation
13
Section 3:Putting Things into Practice

Implementing Grid Search

Implementing Grid Search in Optuna is a bit different from implementing TPE and Random Search. Here, we need to also define the search space object and pass it to optuna.samplers.GridSampler(). The search space object is just a Python dictionary data structure consisting of hyperparameters’ names as the keys and the possible values of the corresponding hyperparameter as the dictionary’s values. GridSampler will stop the hyperparameter tuning process if all of the combinations in the search space have already been evaluated, even though the number of trials, n_trials, passed to the optimize() method has not been reached yet. Furthermore, GridSampler will only get the value stated in the search space no matter the range we pass to the sampling distribution methods, such as suggest_categorical, suggest_discrete_uniform, suggest_int, and suggest_float.

The following code shows how to perform Grid Search in Optuna. The overall procedure to implement...