grid.newpage()
addArrowMark(list(x=unit(.5, "npc"),
y=unit(.5, "npc")),
label="label1",
col="blue")
## how to get the position by mouse click
if(interactive()){
pos <- addArrowMark(label="byClick")
addArrowMark(pos, label="samePosAsAbove")
}
Run the code above in your browser using DataLab