Ggplot - (aes|aesthetic) (plot parameter definition)

> Data Visualization (vis|viz|graphic|image) > R - Ggplot

1 - About

Aesthetic are plots parameters that are given by the data.

For parameters that are not related to the data, see Ggplot - Theme

Such as:

  • coordinate x and y.
  • Color:
    • color: the bar outline,
    • fill: interior colouring
    • alpha
  • group - How the data are grouped (Default to the discrete value of the plot)
  • weight - The variable to be summed.
  • shape - It will use another shape for each point

The aes function maps aesthetic to data frame variable.


3 - Syntax

mapping = aes(x=carat, y=price)

The aes function (map|set):

  • the variable carat to x
  • and the variable price to y.

Mappings usually stay the same on a plot, so they are stored as defaults

3.1 - Example

# The carat variable will be x and the prices will be y 
p <- ggplot(diamonds, aes(x=carat,y=price))
# This code will map the colour to the green variable
p + geom_point(aes(colour = "green"))
# This code will show the colour green for all geoms
p + geom_point(colour = "green")
ggplot(diamonds, aes(x=carat, y=price))
+ geom_point(aes(colour = carat))
  • fill. To slice an histogram, area with colour.
ggplot(diamonds, aes(x=price))
+geom_histogram(aes(fill = clarity))