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Machine Learning Algorithms

You're reading from  Machine Learning Algorithms

Product type Book
Published in Jul 2017
Publisher Packt
ISBN-13 9781785889622
Pages 360 pages
Edition 1st Edition
Languages
Toc

Table of Contents (22) Chapters close

Title Page
Credits
About the Author
About the Reviewers
www.PacktPub.com
Customer Feedback
Preface
1. A Gentle Introduction to Machine Learning 2. Important Elements in Machine Learning 3. Feature Selection and Feature Engineering 4. Linear Regression 5. Logistic Regression 6. Naive Bayes 7. Support Vector Machines 8. Decision Trees and Ensemble Learning 9. Clustering Fundamentals 10. Hierarchical Clustering 11. Introduction to Recommendation Systems 12. Introduction to Natural Language Processing 13. Topic Modeling and Sentiment Analysis in NLP 14. A Brief Introduction to Deep Learning and TensorFlow 15. Creating a Machine Learning Architecture

Evaluation methods based on the ground truth


In this section, we present some evaluation methods that require the knowledge of the ground truth. This condition is not always easy to obtain because clustering is normally applied as an unsupervised method; however, in some cases, the training set has been manually (or automatically) labeled, and it's useful to evaluate a model before predicting the clusters of new samples.

Homogeneity

An important requirement for a clustering algorithm (given the ground truth) is that each cluster should contain only samples belonging to a single class. In Chapter 2, Important Elements in Machine Learning, we have defined the concepts of entropy H(X) and conditional entropy H(X|Y), which measures the uncertainty of X given the knowledge of Y. Therefore, if the class set is denoted as C and the cluster set as K, H(C|K) is a measure of the uncertainty in determining the right class after having clustered the dataset. To have a homogeneity score, it's necessary...

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