Themes from scratch

Introduzione alla visualizzazione dei dati con ggplot2

Rick Scavetta

Founder, Scavetta Academy

The themes layer

All non-data ink
Visual elements not part of the data

The themes layer

All non-data ink
Visual elements not part of the data

Three types

type
text
line
rectangle

The themes layer

All non-data ink
Visual elements not part of the data

Three types

type	modified using
text	element_text()
line	element_line()
rectangle	element_rect()

A starting plot...

ggplot(iris, aes(x = Sepal.Length, y = Sepal.Width, color = Species)) + 
  geom_jitter(alpha = 0.6)

The text elements


text
  axis.title 
    axis.title.x
      axis.title.x.top
      axis.title.x.bottom 
    axis.title.y
      axis.title.y.left
      axis.title.y.right 
  title 
    legend.title 
    plot.title
    plot.subtitle 
    plot.caption 
    plot.tag
  axis.text 
    axis.text.x 
      axis.text.x.top
      axis.text.x.bottom 
    axis.text.y
      axis.text.y.left
      axis.text.y.right
  legend.text
  strip.text
    strip.text.x
    strip.text.y

The text elements

theme(
text, 
  axis.title, 
    axis.title.x,
      axis.title.x.top, 
      axis.title.x.bottom, 
    axis.title.y, 
      axis.title.y.left,
      axis.title.y.right, 
  title, 
    legend.title, 
    plot.title,
    plot.subtitle, 
    plot.caption, 
    plot.tag, 
  axis.text, 
    axis.text.x, 
      axis.text.x.top,
      axis.text.x.bottom, 
    axis.text.y, 
      axis.text.y.left, 
      axis.text.y.right,
  legend.text,
  strip.text, 
    strip.text.x, 
    strip.text.y)

Adjusting theme elements

ggplot(iris, aes(x = Sepal.Length, y = Sepal.Width, color = Species)) + 
  geom_jitter(alpha = 0.6) +
  theme(axis.title = element_text(color = "blue"))

A starting plot...

ggplot(iris, aes(x = Sepal.Length, y = Sepal.Width, color = Species)) + 
  geom_jitter(alpha = 0.6)

Line elements

theme(
line,
  axis.ticks,
    axis.ticks.x, 
      axis.ticks.x.top,
      axis.ticks.x.bottom,
    axis.ticks.y,
      axis.ticks.y.left, 
      axis.ticks.y.right,
    axis.line,
      axis.line.x, 
        axis.line.x.top,
        axis.line.x.bottom, 
      axis.line.y,
        axis.line.y.left, 
        axis.line.y.right, 
  panel.grid,
    panel.grid.major, 
      panel.grid.major.x, 
      panel.grid.major.y, 
    panel.grid.minor,
      panel.grid.minor.x,
      panel.grid.minor.y)

A starting plot...

ggplot(iris, aes(x = Sepal.Length, y = Sepal.Width, color = Species)) + 
  geom_jitter(alpha = 0.6)

Rect elements

theme(
rect,
  legend.background, 
  legend.key,
  legend.box.background, 
  panel.background,
  panel.border,
  plot.background, 
  strip.background, 
    strip.background.x, 
    strip.background.y)

Hierarchical naming reflects inheritance rules

e.g. Text

text
  axis.title 
    axis.title.x
      axis.title.x.top
      axis.title.x.bottom 
    axis.title.y
      axis.title.y.left
      axis.title.y.right

e.g. Lines

line
  axis.ticks
    axis.ticks.x 
      axis.ticks.x.top
      axis.ticks.x.bottom
    axis.ticks.y
      axis.ticks.y.left,
      axis.ticks.y.right
    axis.line
      axis.line.x 
        axis.line.x.top
        axis.line.x.bottom
      axis.line.y
        axis.line.y.left 
        axis.line.y.right

element_blank()

ggplot(iris, aes(x = Sepal.Length, y = Sepal.Width, color = Species)) + 
  geom_jitter(alpha = 0.6) + 
  theme(line = element_blank(),
        rect = element_blank(),
        text = element_blank())

Let's practice!

Introduzione alla visualizzazione dei dati con ggplot2