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

Using gradient boosted regression

We can sometimes improve upon random forest models by using gradient boosting instead. Similar to random forests, gradient boosting is an ensemble method that combines learners, typically trees. But unlike random forests, each tree is built to learn from the errors of previous trees. This can significantly improve our ability to model complexity.

Although gradient boosting is not particularly prone to overfitting, we have to be even more careful with our hyperparameter tuning than we have to be with random forest models. We can slow the learning rate, also known as shrinkage. We can also adjust the number of estimators (trees). The choice of learning rate influences the number of estimators needed. Typically, if we slow the learning rate, our model will require more estimators.

There are several tools for implementing gradient boosting. We will work with two of them: gradient boosted regression from scikit-learn and XGBoost.

We will work with...