Book Image

Time Series Analysis with Python Cookbook

By : Tarek A. Atwan
Book Image

Time Series Analysis with Python Cookbook

By: Tarek A. Atwan

Overview of this book

Time series data is everywhere, available at a high frequency and volume. It is complex and can contain noise, irregularities, and multiple patterns, making it crucial to be well-versed with the techniques covered in this book for data preparation, analysis, and forecasting. This book covers practical techniques for working with time series data, starting with ingesting time series data from various sources and formats, whether in private cloud storage, relational databases, non-relational databases, or specialized time series databases such as InfluxDB. Next, you’ll learn strategies for handling missing data, dealing with time zones and custom business days, and detecting anomalies using intuitive statistical methods, followed by more advanced unsupervised ML models. The book will also explore forecasting using classical statistical models such as Holt-Winters, SARIMA, and VAR. The recipes will present practical techniques for handling non-stationary data, using power transforms, ACF and PACF plots, and decomposing time series data with multiple seasonal patterns. Later, you’ll work with ML and DL models using TensorFlow and PyTorch. Finally, you’ll learn how to evaluate, compare, optimize models, and more using the recipes covered in the book.
Table of Contents (18 chapters)

Chapter 14: Outlier Detection Using Unsupervised Machine Learning

In Chapter 8, Outlier Detection Using Statistical Methods, you explored parametric and non-parametric statistical techniques to spot potential outliers. The methods were simple, interpretable, and yet quite effective.

Outlier detection is not straightforward, mainly due to the ambiguity surrounding the definition of what an outlier is specific to your data or the problem that you are trying to solve. For example, though common, some of the thresholds used in Chapter 8, Outlier Detection Using Statistical Methods, are still arbitrary and not a rule that you should follow. Therefore, having domain knowledge is vital to making the proper judgment when spotting outliers.

In this chapter, you will be introduced to a handful of machine learning-based methods for outlier detection. Most of the machine learning techniques for outlier detection are considered unsupervised outlier detection methods, such as Isolation Forests...