Book Image

Data Science Using Python and R

By : Chantal D. Larose, Daniel T. Larose
Book Image

Data Science Using Python and R

By: Chantal D. Larose, Daniel T. Larose

Overview of this book

Data science is hot. Bloomberg named a data scientist as the ‘hottest job in America’. Python and R are the top two open-source data science tools using which you can produce hands-on solutions to real-world business problems, using state-of-the-art techniques. Each chapter in the book presents step-by-step instructions and walkthroughs for solving data science problems using Python and R. You’ll learn how to prepare data, perform exploratory data analysis, and prepare to model the data. As you progress, you’ll explore what are decision trees and how to use them. You’ll also learn about model evaluation, misclassification costs, naïve Bayes classification, and neural networks. The later chapters provide comprehensive information about clustering, regression modeling, dimension reduction, and association rules mining. The book also throws light on exciting new topics, such as random forests and general linear models. The book emphasizes data-driven error costs to enhance profitability, which avoids the common pitfalls that may cost a company millions of dollars. By the end of this book, you’ll have enough knowledge and confidence to start providing solutions to data science problems using R and Python.
Table of Contents (20 chapters)
Free Chapter
1
ABOUT THE AUTHORS
17
INDEX
18
END USER LICENSE AGREEMENT

8.5 APPLICATION OF NAÏVE BAYES CLASSIFICATION

We will use the wine_ flag_training and wine_flag_test data sets to demonstrate how we use Naïve Bayes to classify a response variable. Let us say we want to predict whether a wine is red or white based on whether the wine has high or low alcohol and sugar content. Alcohol and sugar content values are considered low if they are below the median for that variable, and high if they are above the median.

First, we construct two contingency tables, one for Type and Alcohol_flag and another for Type and Sugar_flag. Recall that the class values of target variable constitute the rows, and the class values of predictor variables constitute the columns. The contingency table for Type and Alcohol_flag is shown in Figure 8.1, while the contingency table for Type and Sugar_flag is shown in Figure 8.2.

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Figure 8.1 Contingency table from R for Type and Alcohol_flag.

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Figure 8.2 Contingency table from R for Type and Sugar_flag.

We can use...