ggplot2 layers

Introduction to Data Visualization with ggplot2

Rick Scavetta

Founder, Scavetta Academy

ggplot2 package

The grammar of graphics implemented in R
Two key concepts:
1. Layer grammatical elements
2. Aesthetic mappings

Data

Iris dataset

¹ Fisher, R. A. (1936) The use of multiple measurements in taxonomic problems. Annals of Eugenics, 7, Part II, 179–188. ² Anderson, Edgar (1935). The irises of the Gaspe Peninsula, Bulletin of the American Iris Society, 59, 2–5.

Iris dataset

iris

    Sepal.Length Sepal.Width Petal.Length Petal.Width    Species
1            5.1         3.5          1.4         0.2     setosa
2            4.9         3.0          1.4         0.2     setosa
3            4.7         3.2          1.3         0.2     setosa
...
50           5.0         3.3          1.4         0.2     setosa
51           7.0         3.2          4.7         1.4 versicolor
52           6.4         3.2          4.5         1.5 versicolor
53           6.9         3.1          4.9         1.5 versicolor
...
100          5.7         2.8          4.1         1.3 versicolor
101          6.3         3.3          6.0         2.5  virginica
102          5.8         2.7          5.1         1.9  virginica
103          7.1         3.0          5.9         2.1  virginica
...
150          5.9         3.0          5.1         1.8  virginica

Aesthetics

Iris aesthetics

Geometries

Iris geometries

g <- ggplot(iris, aes(x = Sepal.Length, y = Sepal.Width)) +
  geom_jitter()
g

Themes

Iris themes

g <- g +
  labs(x = "Sepal Length (cm)", y = "Sepal Width (cm)") +
  theme_classic()
g

Let's practice!

Introduction to Data Visualization with ggplot2