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Machine Learning Algorithms

You're reading from   Machine Learning Algorithms Popular algorithms for data science and machine learning

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Product type Paperback
Published in Aug 2018
Publisher Packt
ISBN-13 9781789347999
Length 522 pages
Edition 2nd Edition
Languages
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Author (1):
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Giuseppe Bonaccorso Giuseppe Bonaccorso
Author Profile Icon Giuseppe Bonaccorso
Giuseppe Bonaccorso
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Table of Contents (19) Chapters Close

Preface 1. A Gentle Introduction to Machine Learning FREE CHAPTER 2. Important Elements in Machine Learning 3. Feature Selection and Feature Engineering 4. Regression Algorithms 5. Linear Classification Algorithms 6. Naive Bayes and Discriminant Analysis 7. Support Vector Machines 8. Decision Trees and Ensemble Learning 9. Clustering Fundamentals 10. Advanced Clustering 11. Hierarchical Clustering 12. Introducing Recommendation Systems 13. Introducing Natural Language Processing 14. Topic Modeling and Sentiment Analysis in NLP 15. Introducing Neural Networks 16. Advanced Deep Learning Models 17. Creating a Machine Learning Architecture 18. Other Books You May Enjoy

Finding the optimal hyperparameters through a grid search

Finding the best hyperparameters (they are called this because they influence the parameters learned during the training phase) is not always easy, and there are seldom good methods to start from. Personal experience (a fundamental element) must be aided by an efficient tool, such as GridSearchCV, which automates the training process of different models and provides the user with optimal values using cross-validation.

As an example, we show how to use grid search to find the best penalty and strength factors for logistic regression based on the Iris dataset:

import multiprocessing

from sklearn.datasets import load_iris
from sklearn.model_selection import GridSearchCV

iris = load_iris()

param_grid = [
{
'penalty': [ 'l1', 'l2' ],
'C': [ 0.5, 1.0, 1.5, 1.8, 2.0, 2.5]
}
]

gs...
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