Book Image

Data Manipulation with R - Second Edition

By : Jaynal Abedin, Kishor Kumar Das
Book Image

Data Manipulation with R - Second Edition

By: Jaynal Abedin, Kishor Kumar Das

Overview of this book

<p>This book starts with the installation of R and how to go about using R and its libraries. We then discuss the mode of R objects and its classes and then highlight different R data types with their basic operations.</p> <p>The primary focus on group-wise data manipulation with the split-apply-combine strategy has been explained with specific examples. The book also contains coverage of some specific libraries such as lubridate, reshape2, plyr, dplyr, stringr, and sqldf. You will not only learn about group-wise data manipulation, but also learn how to efficiently handle date, string, and factor variables along with different layouts of datasets using the reshape2 package.</p> <p>By the end of this book, you will have learned about text manipulation using stringr, how to extract data from twitter using twitteR library, how to clean raw data, and how to structure your raw data for data mining.</p>
Table of Contents (13 chapters)
Data Manipulation with R Second Edition
Credits
About the Authors
About the Reviewers
www.PacktPub.com
Preface
Index

Character manipulation


In any statistical software, all the data is expected to be either numeric or at least a factor, but sometimes we have to work with character data. In the area of text mining, character, or string, manipulation is the most important. R has complete functionality to manipulate character (string) data for further analysis. Besides default R functionality, there is one contributed package to deal with character data, which is more user friendly and intuitive, compared to the base R counterpart. Wickham developed the stringr package in 2010 to manipulate character data with some user friendly functions. In this section, we will introduce different functions and their counterparts in a table, so that the readers are able to use the functions from the stringr package easily:

Base R functions

stringr functions

paste(): This function is used to concatenate a vector of characters, with a default separator as a space.

str_c(): This has a functionality similar to paste(),...