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Python Machine Learning

You're reading from   Python Machine Learning Learn how to build powerful Python machine learning algorithms to generate useful data insights with this data analysis tutorial

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Product type Paperback
Published in Sep 2015
Publisher Packt
ISBN-13 9781783555130
Length 454 pages
Edition 1st Edition
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Author (1):
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Sebastian Raschka Sebastian Raschka
Author Profile Icon Sebastian Raschka
Sebastian Raschka
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Table of Contents (15) Chapters Close

Preface 1. Giving Computers the Ability to Learn from Data 2. Training Machine Learning Algorithms for Classification FREE CHAPTER 3. A Tour of Machine Learning Classifiers Using Scikit-learn 4. Building Good Training Sets – Data Preprocessing 5. Compressing Data via Dimensionality Reduction 6. Learning Best Practices for Model Evaluation and Hyperparameter Tuning 7. Combining Different Models for Ensemble Learning 8. Applying Machine Learning to Sentiment Analysis 9. Embedding a Machine Learning Model into a Web Application 10. Predicting Continuous Target Variables with Regression Analysis 11. Working with Unlabeled Data – Clustering Analysis 12. Training Artificial Neural Networks for Image Recognition 13. Parallelizing Neural Network Training with Theano Index

Locating regions of high density via DBSCAN

Although we can't cover the vast number of different clustering algorithms in this chapter, let's at least introduce one more approach to clustering: Density-based Spatial Clustering of Applications with Noise (DBSCAN). The notion of density in DBSCAN is defined as the number of points within a specified radius Locating regions of high density via DBSCAN.

In DBSCAN, a special label is assigned to each sample (point) using the following criteria:

  • A point is considered as core point if at least a specified number (MinPts) of neighboring points fall within the specified radius Locating regions of high density via DBSCAN
  • A border point is a point that has fewer neighbors than MinPts within Locating regions of high density via DBSCAN, but lies within the Locating regions of high density via DBSCAN radius of a core point
  • All other points that are neither core nor border points are considered as noise points

After labeling the points as core, border, or noise points, the DBSCAN algorithm can be summarized in two simple steps:

  1. Form a separate cluster for each core point or a connected group of core points (core...
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