crossfading between raster layers in gganimate

raster_fade.R

library(ggplot2)
library(gganimate)

mygridstart <- tidyr::crossing(x = 1:10, y = 1:10)

mygrid <- rbind(mygridstart, mygridstart, mygridstart)
mygrid$rep <- sort(rep(1:3, nrow(mygrid)/3))
mygrid$pointgroup <- rep(1:100, 3)
mygrid$f <- factor(sample(1:3, replace=TRUE, size = nrow(mygrid)))

ggplot(mygrid,
       aes(x = x, y = y, color = f, fill = f, group = pointgroup)) +
  geom_raster() +
  transition_states(rep) +
  enter_fade() +
  exit_fade()