alternative to http://stackoverflow.com/a/42894091/3315962

gistfile1.txt

library(ReporteRs)
require( ggplot2 )
myplot <- qplot(Sepal.Length, Petal.Length, 
                data = iris, color = Species,
                size = Petal.Width, alpha = I(0.7) )
xx <- pptx()
xx <- addSlide(xx, "Title and Content")

# get slide dimensions
slide_dims <- dim(xx)$slide.dim

xx <- addPlot(xx, fun = print, x = myplot, 
              offx = 0, offy = 0, 
              width = slide_dims["width"], height = slide_dims["height"])
writeDoc(xx, "test.pptx")