ggalt

https://github.com/hrbrmstr/ggalt

A compendium of ‘geoms’, ‘coords’ and ‘stats’ for ‘ggplot2’, including splines, 1d and 2d densities, univariate average shifted histograms and a new map coordinate system based on the ‘PROJ.4’-library..

# Example from https://github.com/hrbrmstr/ggalt
library(ggplot2)
library(gridExtra)
library(ggalt)

set.seed(1492)
dat <- data.frame(x=c(1:10, 1:10, 1:10),
                  y=c(sample(15:30, 10), 2*sample(15:30, 10), 3*sample(15:30, 10)),
                  group=factor(c(rep(1, 10), rep(2, 10), rep(3, 10)))
)

ggplot(dat, aes(x, y, group=group, color=factor(group))) +
  geom_point(color="black") +
  geom_smooth(se=FALSE, linetype="dashed", size=0.5) +
  geom_xspline(spline_shape=-0.4, size=0.5)

## Alternate 2D density plots

ggplot(faithful, aes(x = eruptions, y = waiting)) +
       geom_point() +
       xlim(0.5, 6) +
       ylim(40, 110) + 
  geom_bkde2d(bandwidth=c(0.5, 4))