Book Image

Machine Learning with Swift

By : Jojo Moolayil, Alexander Sosnovshchenko, Oleksandr Baiev
Book Image

Machine Learning with Swift

By: Jojo Moolayil, Alexander Sosnovshchenko, Oleksandr Baiev

Overview of this book

Machine learning as a field promises to bring increased intelligence to the software by helping us learn and analyse information efficiently and discover certain patterns that humans cannot. This book will be your guide as you embark on an exciting journey in machine learning using the popular Swift language. We’ll start with machine learning basics in the first part of the book to develop a lasting intuition about fundamental machine learning concepts. We explore various supervised and unsupervised statistical learning techniques and how to implement them in Swift, while the third section walks you through deep learning techniques with the help of typical real-world cases. In the last section, we will dive into some hard core topics such as model compression, GPU acceleration and provide some recommendations to avoid common mistakes during machine learning application development. By the end of the book, you'll be able to develop intelligent applications written in Swift that can learn for themselves.
Table of Contents (18 chapters)
Title Page
Packt Upsell
Contributors
Preface
Index

Choosing the number of clusters


If you don't know in advance how many clusters you have, then how do you choose the optimal k? This is essentially an egg-and-chicken problem. Several approaches are popular and we'll discuss one of them: the elbow method.

Do you remember those mysterious WCSS that we calculated on every iteration of k-means? This measure tells us how much points in every cluster are different from their centroid. We can calculate it for several different k values and plot the result. It usually looks somewhat similar to the plot on the following graph:

Figure 4.3: WCSS plotted against the number of clusters

This plot should remind you about the similar plots of loss functions from Chapter 3K-Nearest Neighbors Classifier. It shows how well our model fits the data. The idea of the elbow method is to choose the k value after which the result is not going to improve sharply anymore. The name comes from the similarity of the plot to an arm. We choose the point at the elbow, marked...