aes function is a method in ggplot2 called an Aesthetic Mapping.
This function allows you to map data, features or columns from your data
set to the map. The basic example is as follows.
This aesthetic will create a map from x to y for your plot.
You almost always pass the function to a
ggplot call to create a base
plot before adding a geometry. Here is a full example in context.
ggplot(mpg, aes(x = displ, y = hwy)) + geom_point()
There is more you can do with
aes and more you might see when
reviewing tutorials or docs online. Let’s walk through some examples of
aes you might see.
You may see that we can create an
aes without specifying the x and y
names for the pareters. In the following aes, the x and y are infered.
You can also modify x and y with calculations.
aes(x = mpg ^ 2, y = wt / cyl)
You may also see the use of
color for US).
Using these parameters usually creates groups of plots by a factor. Here
are two examples.
library(ggplot2) ggplot(mpg, aes(x = displ, y = hwy, colour = trans)) + geom_point()
ggplot(mpg, aes(x = displ, y = hwy, shape = trans)) + geom_point()
## Warning: The shape palette can deal with a maximum of 6 discrete values because ## more than 6 becomes difficult to discriminate; you have 10. Consider ## specifying shapes manually if you must have them. ## Warning: Removed 96 rows containing missing values (geom_point).