Aligning and arranging charts in ggplot

Question

I have two plots in ggplot with similar ranges on the axis that I would like to align.

Using:

library(grid)
grid.newpage()
grid.draw(rbind(ggplotGrob(g1)         


        

Answer 1

you simply need to edit the heights of the gtable,

library(ggplot2)
library(grid)
g1 <- g2 <- ggplotGrob(qplot(1,1))

g <- rbind(g1,g2,size="last")
id <- g$layout$t[g$layout$name == "panel"]
g$heights[id] <- lapply(c(1,4), "unit", "null")
grid.newpage()
grid.draw(g)

Edit: with the more specific instructions, I'd suggest a different strategy: add the first panel only to the gtable of the second plot,

p1 <- ggplot(df1)+geom_point(aes(x=x,y=y))
p2 <- ggplot(df2)+geom_text(aes(x=x,y=0,label=r),angle=45,size=2)
snug <- theme_bw() + theme(plot.margin=unit(c(0.5,0.5,0,0),"line"))

library(gtable)
g1=gtable_filter(ggplotGrob(p1 + snug), pattern = "panel", trim = TRUE, fixed=TRUE)
g2=ggplotGrob(p2 + snug)

g <- g2
g <- gtable_add_rows(g, unit(0.2, "null"), 0)
g <- gtable_add_grob(g, g1, 1, 4)
grid.newpage()
grid.draw(g)