Repeat axis lines on facet panels

Stefan McKinnon Edwards sme@iysik.com

2025-07-22

Deprecation notice: The facet_rep_wrap and facet_rep_lab have been deprecated in lemon v. 0.5.1. Instead, we refer to the similar solutions in ggh4x’ facet_wrap2 and facet_grid2.

ggplot2 offers the fantastic option for displaying complex data in forms of ‘many multiple’, i.e. the facets. From the example of facet_grid:

p <- ggplot(mpg, aes(displ, cty)) + geom_point()
p + facet_grid(drv ~ cyl) + theme_bw()
Faceting works quite well in its default form. When the panel’s borders are drawn, nothing lacks.
Faceting works quite well in its default form. When the panel’s borders are drawn, nothing lacks.

In the above example, the panel’s borders are drawn with the default settings of theme_bw().

If we desire the axis lines, such as those given in this package, the distinction of the panels disappears.

library(lemon)
p <- p + coord_capped_cart(bottom='both', left='both') +
  theme_bw() + theme(panel.border=element_blank(), axis.line=element_line())
p + facet_grid(drv ~ cyl)
The optimised axis lines are gone from inner panels.
The optimised axis lines are gone from inner panels.

The above example is re-created below with both left- and bottom-axis lines repeated.

library(ggh4x)
## 
## Attaching package: 'ggh4x'
## The following objects are masked from 'package:lemon':
## 
##     GeomPointPath, geom_pointpath
p + facet_grid2(drv ~ cyl, axes = TRUE, remove_labels = TRUE) + 
  coord_capped_cart(bottom='both', left='both') +
  theme_bw() + theme(panel.border=element_blank(), axis.line=element_line())
## Coordinate system already present. Adding new coordinate system, which will
## replace the existing one.
Axis lines are repeated across all panels by using facet_rep_grid of the lemon package.
Axis lines are repeated across all panels by using facet_rep_grid of the lemon package.

Keeping (some) labels

In the following example, we change the facet from a grid to being wrapped on the interaction of drv and cyl, and add free scaling on y-axis. facet_wrap would normally print the y-axis tick labels for each panel, but still ignores the x-axis.

p + facet_wrap(~ interaction(cyl, drv), scales='free_y')
facet_wrap keeps y-axis label ticks with scales='free_y'.
facet_wrap keeps y-axis label ticks with scales='free_y'.

A work around by keeping both axes free scale, and fixing the x-axis with either scale_x_continuous or limits in cord_*, but the same x-axis tick labels are repeated. And this is a bit tedious.

p + facet_wrap(~ interaction(cyl, drv), scales='free') + 
  coord_capped_cart(bottom='both', left='both', xlim=c(2,7))
## Coordinate system already present. Adding new coordinate system, which will
## replace the existing one.
X-axis is entirely fixed, and the plot is littered with x-axis tick labels.
X-axis is entirely fixed, and the plot is littered with x-axis tick labels.

We can specify which inner labels to keep with facet_rap2(..., remove_labels) . The default is to keep all labels, but we can specify to remove all “x” or all “y”.

p + facet_wrap2(~ interaction(cyl, drv), scales = 'free_y', axes = TRUE, remove_labels = "x")
With repeat.tick.labels we are free to specify which sides to keep.
With repeat.tick.labels we are free to specify which sides to keep.

Examples

There are many possibilities. Examples given below (but not executed), and they might not be pretty.

p + facet_wrap2(~ interaction(cyl, drv), scales = 'free_y', axes = TRUE, remove_labels = FALSE)
p + facet_wrap2(~ interaction(cyl, drv), scales = 'free_y', axes = TRUE, remove_labels = "y")
p + facet_wrap2(~ interaction(cyl, drv), scales = 'free_y', axes = TRUE, remove_labels = "x")
p + scale_x_continuous(sec.axis = dup_axis()) +
  facet_wrap2(~ interaction(cyl, drv), scales = 'free_y', axes = TRUE, remove_labels = FALSE)

Translating between lemon’s and ggh4x’ facets

lemon ggh4x
facet_rep_wrap(...) facet_wrap2(...)
facet_rep_grid(...) facet_grid2(...)
repeat.tick.labels remove_labels, only “none”, FALSE, “x”, “y”, “all” or TRUE
(None) axes, only “margin”, FALSE, “x”, “y”, “all” or TRUE