The axis values are -6,-4,-2,0,2,4,6 with some y values in a density plot.
Is it possible to add dotted vertical lines on certain x-axis values (Forex: -3 and +3 )using ggplot?
library(ggplot2)
df <- data.frame(x = rnorm(1000, 0, 1), y = rnorm(1000,
0, 2), z = rnorm(1000, 2, 1.5))
df.m <- melt(df)
ggplot(df.m) + geom_freqpoly(aes(x = value,
y = ..density.., colour = variable))