Is there any way to set the line end style or the line join style in ggplot?

Question

For a description of the line end and line join styles available in R, see http://students.washington.edu/mclarkso/documents/line%20styles%20Ver2.pdf

For ggplot, I already searched in plot_theme() and the github list of ggplot2 opts https://github.com/hadley/ggplot2/wiki/%2Bopts%28%29-List but found no leads, so I'm thinking it's not possible to change these in ggplot.

Answer 1

A search with Baron's website (linked from RSiteSearch) brings up this method for setting the grid's lineend parameter. 'gglot2' functions uses the grid package so searching with grid-terms like lineend will be more productive for ferreting out obscure features:

http://finzi.psych.upenn.edu/R/library/ggplot2/html/geom_path.html

 xy <- data.frame(x = rep(c(1:3,3:9), times=3), y = rep(10:1, times=3), 
                 type = rep(LETTERS[1:2], each=5), type2 = rep(LETTERS[3:5], each=10))
 myplot <- ggplot(data = xy)+
                  geom_path(aes(x = x, y = y), size=4, lineend="butt", 
                             linejoin="mitre")+facet_grid(type ~ type2)
 myplot

(I was not convinced that all the linejoin parameter were being acted upon, but the lineend settings were being honored and the round joins were definitely different.)