The goal of this tutorial is to learn how to define the breaks in a geom point plot in ggplot.
# First we load the libraries
library(ggplot2)
# In this example we will use the open repository of plants classification Iris.
data("iris")
str(iris)
## 'data.frame': 150 obs. of 5 variables:
## $ Sepal.Length: num 5.1 4.9 4.7 4.6 5 5.4 4.6 5 4.4 4.9 ...
## $ Sepal.Width : num 3.5 3 3.2 3.1 3.6 3.9 3.4 3.4 2.9 3.1 ...
## $ Petal.Length: num 1.4 1.4 1.3 1.5 1.4 1.7 1.4 1.5 1.4 1.5 ...
## $ Petal.Width : num 0.2 0.2 0.2 0.2 0.2 0.4 0.3 0.2 0.2 0.1 ...
## $ Species : Factor w/ 3 levels "setosa","versicolor",..: 1 1 1 1 1 1 1 1 1 1 ...
# Let's plot the petal length vs petal width
ggplot() + geom_point(data = iris, aes(x = Petal.Width, y = Petal.Length,color = Species))
# We can use scale x continuous to define the breaks in the x axis
# Let's define breaks every 0.25
ggplot() + geom_point(data = iris, aes(x = Petal.Width, y = Petal.Length,color = Species)) +
scale_x_continuous(breaks = seq(from = 0, to = 2.5, by = 0.25))
# We can now use scale y continuous to do the same in the y axis
ggplot() + geom_point(data = iris, aes(x = Petal.Width, y = Petal.Length,color = Species)) +
ylim(0,7) +
scale_x_continuous(breaks = seq(from = 0, to = 2.5, by = 0.25))+
scale_y_continuous(breaks = seq(from = 0.0, to = 7, by = 0.5))
## Scale for 'y' is already present. Adding another scale for 'y', which
## will replace the existing scale.
In this tutorial we have learnt how to define manually the breaks of the axes in ggplot. This can be useful if we want to break the axes in a certain number or period.