The Big R-Book

♣17♣Data Wrangling in the tidyverse

An iconic effort to obtain a certain form of standardization is the work around the tidyverse. The tidyverse defines “tidy data” and “tidy code” in a logical and compelling matter. Adhering to those rules makes code more readable, easier to maintain and more fun to build.

It is possible to program in R without the tidyverse – as we did in Chapter 4 “The Basics of R” on page 21 – because it is important to know and be able to read and understand base-R code. Knowing both, we invite you to make your own, informed choice.

In Chapter 7 “Tidy R with the Tidyverse” on page 121 we already introduced the tidyverse and largely explained operators and ideas. In this chapter, we focus on obtaining “tidy data.”

17.1 Importing the Data

17.1.1 Importing from an SQL RDBMS

In this section we will assume that the reader is familiar with concepts such as RDBMS, relational data, primary key, relation, foreign key, etc. from Chapter 14 “SQL” on page 223. We also assume that the reader already has data in R (tibble or data frame) as explained in Chapter 15 “Connecting R to an SQL Database” on page 253. Further, we will also use the database design of Figure 14.4 on page 245.

First, we remind the reader of the functions to connect to a database and retrieve data from it. These functions were already presented on page 254 in Chapter 15.

# -- 
library(RMySQL) 
# -- The functions as mentioned earlier: 
# db_get_data 
# Get data from a MySQL database 
# Arguments: ...