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

3.6 REEXPRESSION OF CATEGORICAL DATA AS NUMERIC

Figure 3.4 shows a bar graph5 of the education field. Note that the field is categorical, meaning that there is no ordering of the field values. In other words, if we left the field as it is, then our data science algorithms would not know that university_degree represents more education than basic.4yr. To provide this information to our algorithms, we transform the data values into numeric values, where it is clear that one value is larger than another. One needs to proceed with care when doing this, so that the relative differences among the various categories are preserved.

Graph in R of the education variable, with bars for unknown, University.degree, Professional.course, illiterate, High.school, Basic.9y, Basic.6y, and Basic.4y. The highest bar is University.degree.

Figure 3.4 Bar graph in R of the education variable.

Table 3.1 shows how we plan to accomplish this transformation. The value of 12 for professional course was obtained from the publication shown in the footnote, as representing an alternative to the usual high‐school course of study. Of course, the unknown values will also need to be reexpressed as missing...