A density plot shows the distribution of numeric variable. In ggplot2, the geom-density() function takes care of the kernel density estimation and plot the results. Only one numeric variable is needed as input.
ggplot2
geom-density()
Most basic density curve
Basic line curve
Colored density curve
Add color
Mean line density curve
Add mean line
Density curve with filled area
Fill area with polygon() function
polygon()
Mirror density curve
Two density curves face to face to compare
