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

PART 2: VISUALIZATION: GRAPHS AND TABLES FOR SUMMARIZING AND ORGANIZING DATA

A.1 Categorical Variables

  • The frequency (or count) of a category is the number of data values in each category. The relative frequency of a particular category for a categorical variable equals its frequency divided by the number of cases.
  • A (relative) frequency distribution for a categorical variable consists of all the categories that the variable assumes, together with the (relative) frequencies for each value. The frequencies sum to the number of cases; the relative frequencies sum to 1.
  • For example, Table A.2 contains the frequency distribution and relative frequency distribution for the variable marital status for the data from Table A.1.
  • A bar chart is a graph used to represent the frequencies or relative frequencies for a categorical variable. Note that the bars do not touch.
    • A Pareto chart is a bar chart where the bars are arranged in decreasing order. Figure A.1 is an example of a Pareto chart.
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