ggplot grobs align with tableGrob

问题:

I'm having difficulty to find solution for aligning ggplot grob and table grob. I tried to follow the instruction here but still didn't give the results I wanted.

library(grid)
library(gridExtra)
library(ggplot2)
library(tibble)
library(gtable)
dat <- tibble::rownames_to_column(mtcars, "car") #convert rownames to first col

plot1 <- ggplot(dat, aes(car, mpg)) +
    geom_bar(stat = "identity") +
    coord_flip()

g1 <- ggplotGrob(plot1)
tb1 <- tableGrob(dat$cyl)
g1 <- gtable_add_cols(g1, unit(0.2, "npc"))
g1 <- gtable_add_grob(g1, grobs = tb1, t=3, l=ncol(g1), b=6, r=ncol(g1))

grid.newpage()
grid.draw(g1)

I would like that each cell in the table be aligned to related bar in histogram, but still couldn't understand how the t,l,b,r be implemented from the layout.This is the output I got

回答1:

By default the cell heights have absolute sizes to accommodate the text, but you can change them to relative units so that they scale with the plot panel,

library(grid)
library(gridExtra)
library(ggplot2)
library(tibble)
library(gtable)
dat <- tibble::rownames_to_column(mtcars, "car") #convert rownames to first col

plot1 <- ggplot(dat, aes(car, mpg)) +
  geom_bar(stat = "identity") +
  coord_flip()

g1 <- ggplotGrob(plot1)
tb1 <- tableGrob(dat$cyl, theme = ttheme_default(10))
tb1$heights = unit(rep(1/(nrow(tb1)), nrow(tb1)), "npc")
tb1$widths = unit.pmax(tb1$widths, unit(2, "lines"))
g1 <- gtable_add_cols(g1, sum(tb1$widths))
g1 <- gtable_add_grob(g1, grobs = tb1, t=6, l=ncol(g1), b=6, r=ncol(g1))

grid.newpage()
grid.draw(g1)