Locate title in top left of grid.arrange

问题

I have two plots arranged side by side with gridExtra::grid.arrange. I can put a title on top of them with the top argument. Problem is, I was requested to locate the title on the top left of the plot.

A reproducible example:

library(ggplot2)
library(gridExtra)

p1 <- qplot(1:20)
p2 <- qplot(30, 35)
grid.arrange(p1, p2, nrow = 1, top = "Title")

which produces

But what I need is:

I read several times the ?arrangeGrob file (I think there lies my answer), but haven't figured out how to achieve it.

回答1:

patchwork is a gridExtra alternative that behaves more like ggplot than grid, including how its plot_annotate handles titles:

library(ggplot2)
library(patchwork)

qplot(1:20) + qplot(30, 35) + plot_annotation(title = 'Title')

If you want to adjust it further, its theme parameter accepts a ggplot theme call.

回答2:

Using top argument:

grid.arrange(p1, p2, nrow = 1, top = grid::textGrob("Title", x = 0, hjust = 0))

来源：https://stackoverflow.com/questions/49685458/locate-title-in-top-left-of-grid-arrange