使用scale_y_continuous函数中的sec_axis函数进行为ggplot2的作图，添加第二纵坐标轴。
How to add a secondary axis
library(ggplot2)
ggplot(data = iris,
aes(x = seq_len(150))) +
geom_line(aes(y = Petal.Width),
size = 0.5) +
xlab("Entry number") +
ylab("Petal Width (cm)") +
geom_line(aes(y = Petal.Length),
size = 0.5,
colour = "steelblue3") +
scale_y_continuous(sec.axis =
sec_axis( ~ . ,
name = "Petal Length (cm)"))
How to rotate the secondary axis
library(ggplot2)
ggplot(data = iris,
aes(x = seq_len(150))) +
geom_line(aes(y = Petal.Width),
size = 0.5) +
xlab("Entry number") +
ylab("Petal Width (cm)") +
geom_line(aes(y = Petal.Length),
size = 0.5,
colour = "steelblue3") +
scale_y_continuous(sec.axis =
sec_axis( ~ . ,
name = "Petal Length (cm)")) +
theme( axis.title.y.right = element_text( angle = 90))