In schloerke/gsoc-ggduo-test: Test package for GSoC 2016 for ggduo

Test

Hard: Make a function that prints the legend of a ggplot2 object. Display the results in a knitr/Rmarkdown document.

grab_legend

This function builds the ggplot2 object, then filters out the legend. Then it returns the gtable object containing the legend. When it is ready to printed, the s3 print method will be invoked

Example:

library(ggplot2)
library(GSoCggduoTest)

histPlot <- qplot(x = Sepal.Length, data = iris, fill = Species, geom = "histogram", binwidth = 1/4)
(right <- histPlot)
(bottom <- histPlot + theme(legend.position = "bottom"))
(top <- histPlot + theme(legend.position = "top"))
(left <- histPlot + theme(legend.position = "left"))

grab_legend(right)
grab_legend(bottom)
grab_legend(top)
grab_legend(left)