How to change color of facet borders when using facet_grid
You might need to use ggplot
's layout table and gtable
functions.
library(ggplot2)
library(gtable)
library(grid)
p <- ggplot(mtcars, aes(mpg, wt)) + geom_point() +
facet_grid(am ~ cyl)
## Get the plot grob
gt <- ggplotGrob(p)
## Check the layout
gtable_show_layout(gt) # Vertical gaps are in columns 5 and 7
# and span rows 4 to 9
# Horizontal gap is in row 8
# and spans columns 4 to 9
## To automate the selection of the relevant rows and columns:
## Find the panels in the layout
## (t, l, b, r refer to top, left, bottom, right);
## The gaps' indices are one to the right of the panels' r index (except the right most panel);
## and one below the panels' b index (except the bottom most panel);
## Rmin and Rmax give the span of the horizontal gap;
## Bmin and Bmax give the span of the vertical gap;
## cols and rows are the columns and row indices of the gaps.
panels = subset(gt$layout, grepl("panel", gt$layout$name), t:r)
# The span of the horizontal gap
Rmin = min(panels$r)
Rmax = max(panels$r) + 1
#The span of the vertical gap
Bmin = min(panels$t) - 1
Bmax = max(panels$t)
# The columns and rows of the gaps
cols = unique(panels$r)[-length(unique(panels$r))] + 1
rows = unique(panels$t)[-length(unique(panels$t))] + 1
# The grob - orange rectangle
g = rectGrob(gp = gpar(col = NA, fill = "orange"))
## Add orange rectangles into the vertical and horizontal gaps
gt <- gtable_add_grob(gt,
rep(list(g), length(cols)),
t=Bmin, l=cols, b=Bmax)
gt <- gtable_add_grob(gt,
rep(list(g), length(rows)),
t=rows, l=Rmin, r=Rmax)
## Draw it
grid.newpage()
grid.draw(gt)
Although a year late, I found this to be an easy fix:
ggplot(mpg, aes(cty, hwy, color = factor(year)))+
geom_point()+
facet_grid(cyl ~ drv) +
theme(panel.margin=unit(.05, "lines"),
panel.border = element_rect(color = "black", fill = NA, size = 1),
strip.background = element_rect(color = "black", size = 1))
UPDATE 2021-06-01
As of ggplot2 3.3.3
, the property panel.margin
is deprecated, and we should use panel.spacing
instead. Therefore, the code should be:
ggplot(mpg, aes(cty, hwy, color = factor(year)))+
geom_point()+
facet_grid(cyl ~ drv) +
theme(panel.spacing = unit(.05, "lines"),
panel.border = element_rect(color = "black", fill = NA, size = 1),
strip.background = element_rect(color = "black", size = 1))