Book Image

Data Cleaning and Exploration with Machine Learning

By : Michael Walker
Book Image

Data Cleaning and Exploration with Machine Learning

By: Michael Walker

Overview of this book

Many individuals who know how to run machine learning algorithms do not have a good sense of the statistical assumptions they make and how to match the properties of the data to the algorithm for the best results. As you start with this book, models are carefully chosen to help you grasp the underlying data, including in-feature importance and correlation, and the distribution of features and targets. The first two parts of the book introduce you to techniques for preparing data for ML algorithms, without being bashful about using some ML techniques for data cleaning, including anomaly detection and feature selection. The book then helps you apply that knowledge to a wide variety of ML tasks. You’ll gain an understanding of popular supervised and unsupervised algorithms, how to prepare data for them, and how to evaluate them. Next, you’ll build models and understand the relationships in your data, as well as perform cleaning and exploration tasks with that data. You’ll make quick progress in studying the distribution of variables, identifying anomalies, and examining bivariate relationships, as you focus more on the accuracy of predictions in this book. By the end of this book, you’ll be able to deal with complex data problems using unsupervised ML algorithms like principal component analysis and k-means clustering.
Table of Contents (23 chapters)
1
Section 1 – Data Cleaning and Machine Learning Algorithms
5
Section 2 – Preprocessing, Feature Selection, and Sampling
9
Section 3 – Modeling Continuous Targets with Supervised Learning
13
Section 4 – Modeling Dichotomous and Multiclass Targets with Supervised Learning
19
Section 5 – Clustering and Dimensionality Reduction with Unsupervised Learning

Summary

In this chapter, we went over a range of feature selection methods, from filter to wrapper to embedded methods. We also saw how they work with categorical and continuous targets. For wrapper and embedded methods, we considered how they work with different algorithms.

Filter methods are very easy to run and interpret and are easy on system resources. However, they do not take other features into account when evaluating each feature. Nor do they tell us how that assessment might vary by the algorithm used. Wrapper methods do not have any of these limitations but they are computationally expensive. Embedded methods are often a good compromise, selecting features based on multivariate relationships and a given algorithm without taxing system resources as much as wrapper methods. We also explored how a dimension reduction method, PCA, could improve our feature selection.

You also probably noticed that I slipped in a little bit of model validation during this chapter. We will...