R for Data Science

Chapter 1. Data Visualization with ggplot2

Introduction

The simple graph has brought more information to the data analyst’s mind than any other device.

John Tukey

This chapter will teach you how to visualize your data using ggplot2. R has several systems for making graphs, but ggplot2 is one of the most elegant and most versatile. ggplot2 implements the grammar of graphics, a coherent system for describing and building graphs. With ggplot2, you can do more faster by learning one system and applying it in many places.

If you’d like to learn more about the theoretical underpinnings of ggplot2 before you start, I’d recommend reading “A Layered Grammar of Graphics”.

Prerequisites

This chapter focuses on ggplot2, one of the core members of the tidyverse. To access the datasets, help pages, and functions that we will use in this chapter, load the tidyverse by running this code:

library(tidyverse)
#> Loading tidyverse: ggplot2
#> Loading tidyverse: tibble
#> Loading tidyverse: tidyr
#> Loading tidyverse: readr
#> Loading tidyverse: purrr
#> Loading tidyverse: dplyr
#> Conflicts with tidy packages --------------------------------
#> filter(): dplyr, stats
#> lag():    dplyr, stats

That one line of code loads the core tidyverse, packages that you will use in almost every data analysis. It also tells you which functions from the tidyverse conflict with functions in base R (or from other packages you might have loaded).

If you run this code and get the error message “there is no package ...