To try out the the release candidate versions of ggplot2 and plyr, run the following code:
install.packages("devtools")
library(devtools)
install_github("plyr", ref = "plyr-1.8-rc")
install_github("gtable", ref = "gtable-0.1.2-rc")
install_github("scales", ref = "scales-0.2.3-rc")
install_github("ggplot2", ref = "ggplot2-0.9.3-rc")After installation has completed, you will need to restart R. Then you can test your existing code that uses plyr and ggplot2.
If you want to use plyr with dev_mode from devtools, please see this.