library(ggplot2) p <- # minimal example qplot(0,0, geom="blank")+ annotate("text",0,0,label="alpha") p g <- # store the plot as a grob ggplotGrob(p) # structure of the grob # grid.ls(g) # rather large! # find a particular grob in the gTree # grid.ls(grob=F, view=T) grid.ls(getGrob(g,"texts", grep = T)) grid.edit(gPath("texts.gTree", "GRID.text"), grep=TRUE, gp=gpar(col="pink")) grid.edit(gPath("texts.gTree", "GRID.text"), grep=TRUE, label=expression(alpha^2), gp=gpar(col="red")) 

data <- data.frame(Name = c("A","B","C","D","E","F","G","H"), y = c(100,200,300,400,200,300,400,350)) # you have to print before grob-ing ggplot(data,aes(x=Name,y=y)) + geom_bar() # locate the lines g <- # store the plot as a grob ggplotGrob(p) grid.ls(g) #notice  #... #panel-3-3 # grill.gTree.383 # panel.background.rect.374 # panel.grid.minor.y.polyline.376 # panel.grid.minor.x.polyline.378 # panel.grid.major.y.polyline.380 # panel.grid.major.x.polyline.382 grid.remove(gPath("GRID.gTree","layout","panel","grill.gTree","panel.grid.minor.x.polyline"),grep=T) grid.remove(gPath("GRID.gTree","layout","panel","grill.gTree","panel.grid.major.x.polyline"),grep=T) grid.remove(gPath("GRID.gTree","layout","panel","grill.gTree","panel.grid.major.y.polyline"),grep=T)