Book Image

Time Series Indexing

By : Mihalis Tsoukalos
Book Image

Time Series Indexing

By: Mihalis Tsoukalos

Overview of this book

Time series are everywhere, ranging from financial data and system metrics to weather stations and medical records. Being able to access, search, and compare time series data quickly is essential, and this comprehensive guide enables you to do just that by helping you explore SAX representation and the most effective time series index, iSAX. The book begins by teaching you about the implementation of SAX representation in Python as well as the iSAX index, along with the required theory sourced from academic research papers. The chapters are filled with figures and plots to help you follow the presented topics and understand key concepts easily. But what makes this book really great is that it contains the right amount of knowledge about time series indexing using the right amount of theory and practice so that you can work with time series and develop time series indexes successfully. Additionally, the presented code can be easily ported to any other modern programming language, such as Swift, Java, C, C++, Ruby, Kotlin, Go, Rust, and JavaScript. By the end of this book, you'll have learned how to harness the power of iSAX and SAX representation to efficiently index and analyze time series data and will be equipped to develop your own time series indexes and effectively work with time series data.
Table of Contents (11 chapters)

Explaining the missing parts

In this section, we are going to show the implementations of the class methods. We begin with the insert() function of the iSAX class, which should not be confused with the insert() function of the Node class. In Python and many other programming languages, classes are independent entities, which means they can have methods with the same name as long as they are unique inside the class namespace.

We are going to present the code of Node.insert() in eight parts. The method accepts two parameters – apart from self, which denotes the current Node object – which are the subsequences we are trying to insert and the iSAX index that the Node instance belongs to.

Why do we need an iSAX instance as a parameter? We need that in order to be able to add new nodes to the iSAX index by accessing iSAX.ht.

The first part of insert() is the following:

    # Follow algorithm from iSAX paper
    def insert...