Book Image

Practical Data Wrangling

By : Allan Visochek
Book Image

Practical Data Wrangling

By: Allan Visochek

Overview of this book

Around 80% of time in data analysis is spent on cleaning and preparing data for analysis. This is, however, an important task, and is a prerequisite to the rest of the data analysis workflow, including visualization, analysis and reporting. Python and R are considered a popular choice of tool for data analysis, and have packages that can be best used to manipulate different kinds of data, as per your requirements. This book will show you the different data wrangling techniques, and how you can leverage the power of Python and R packages to implement them. You’ll start by understanding the data wrangling process and get a solid foundation to work with different types of data. You’ll work with different data structures and acquire and parse data from various locations. You’ll also see how to reshape the layout of data and manipulate, summarize, and join data sets. Finally, we conclude with a quick primer on accessing and processing data from databases, conducting data exploration, and storing and retrieving data quickly using databases. The book includes practical examples on each of these points using simple and real-world data sets to give you an easier understanding. By the end of the book, you’ll have a thorough understanding of all the data wrangling concepts and how to implement them in the best possible way.
Table of Contents (16 chapters)
Title Page
Credits
About the Author
About the Reviewer
www.PacktPub.com
Customer Feedback
Preface

Introducing dplyr


According to the dplyr documentation at http://dplyr.tidyverse.org/, dplyr is a grammar of data manipulation, providing a consistent set of verbs that help you solve the most common data manipulation challenges, as follows:

  • mutate(): Adds new variables that are functions of existing variables
  • select(): Picks variables based on their names
  • filter(): Picks cases based on their values
  • summarize(): Reduces multiple values down to a single summary
  • arrange(): Changes the ordering of the rows
  • group_by(): Allows you to perform any operation by group

While each of the verbs corresponds to a particular function in dplyr, a verb can be thought of more generally as particular action that transform the data in a certain way.

Note

In addition to the verbs listed here, there is also functionality in dplyr that can be used to merge (or join) data from different sources though I won't be covering these features here.

In the following sections, I will demonstrate each of these functions individually...