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Time Series Indexing

You're reading from   Time Series Indexing Implement iSAX in Python to index time series with confidence

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Product type Paperback
Published in Jun 2023
Publisher Packt
ISBN-13 9781838821951
Length 248 pages
Edition 1st Edition
Languages
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Author (1):
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Mihalis Tsoukalos Mihalis Tsoukalos
Author Profile Icon Mihalis Tsoukalos
Mihalis Tsoukalos
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Table of Contents (11) Chapters Close

Preface 1. Chapter 1: An Introduction to Time Series and the Required Python Knowledge 2. Chapter 2: Implementing SAX FREE CHAPTER 3. Chapter 3: iSAX – The Required Theory 4. Chapter 4: iSAX – The Implementation 5. Chapter 5: Joining and Comparing iSAX Indexes 6. Chapter 6: Visualizing iSAX Indexes 7. Chapter 7: Using iSAX to Approximate MPdist 8. Chapter 8: Conclusions and Next Steps 9. Index 10. Other Books You May Enjoy

How iSAX is constructed

This section is going to describe the way an iSAX index is constructed. All the presented information is based on the research paper that describes iSAX. The logical steps are as follows:

  • We begin with a node that is the root of the iSAX index. The root contains no actual data (subsequences) but it contains pointers to all nodes with the specified segments value and a cardinality value of 2, which is a single bit that can only have two values, 0 and 1.
  • After that, we construct the children of the root node, which at this initial point are all terminal nodes without any subsequences in them.
  • We now begin adding subsequences to the children of the root based on their SAX representation.
  • When the threshold value of a terminal node is reached, we perform the splits, based on the specified promotion strategy, and we distribute the subsequences to the two newly created terminal nodes.
  • The process goes on until all subsequences have been inserted...
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