Book Image

Machine Learning Algorithms - Second Edition

Book Image

Machine Learning Algorithms - Second Edition

Overview of this book

Machine learning has gained tremendous popularity for its powerful and fast predictions with large datasets. However, the true forces behind its powerful output are the complex algorithms involving substantial statistical analysis that churn large datasets and generate substantial insight. This second edition of Machine Learning Algorithms walks you through prominent development outcomes that have taken place relating to machine learning algorithms, which constitute major contributions to the machine learning process and help you to strengthen and master statistical interpretation across the areas of supervised, semi-supervised, and reinforcement learning. Once the core concepts of an algorithm have been covered, you’ll explore real-world examples based on the most diffused libraries, such as scikit-learn, NLTK, TensorFlow, and Keras. You will discover new topics such as principal component analysis (PCA), independent component analysis (ICA), Bayesian regression, discriminant analysis, advanced clustering, and gaussian mixture. By the end of this book, you will have studied machine learning algorithms and be able to put them into production to make your machine learning applications more innovative.
Table of Contents (19 chapters)

Agglomerative Clustering

Let's consider the following dataset:

We define affinity, a metric function of two arguments with the same dimensionality, m. The most common metrics (also supported by scikit-learn) are the following:

  • Euclidean or L2 (Minkowski distance with p=2):
  • Manhattan (also known as city block) or L1 (Minkowski distance with p=1):
  • Cosine distance:

The Euclidean distance is normally a good choice, but sometimes it's useful to have a metric whose difference from the Euclidean one gets larger and larger. As discussed in Chapter 9, Clustering Fundamentals, the Manhattan metric has this property. In the following graph, there's a plot representing the distances from the origin of points belonging to the line y = x:

Distances of the point (x, x) from (0, 0) using the Euclidean and Manhattan metrics

The cosine distance is instead useful when we...