facet_wrap2() group by two variables, but label with one

Question

My problem

I have a plot that I have used facet_wrap2() from the ggh4x library to plot. I have used two groupiung variables; groundSurface (either a ground or a surface sample) and fourLoc (a location ID).

On the final plot I only want the "groundSurface showing". Not the "fourLoc" identifier. i.e. no "BE" and "mere" labels. Only "ground" or "surface".

Here is an example plot.

Here is my code:

library(ggh4x)
library(ggplot2)

p1t <- ggplot(test, aes(x=DateTime, y=mAODscale)) +
  geom_line() +
  facet_wrap2(groundSurface ~ fourLoc, drop=FALSE, ncol=2, strip=strip_nested(bleed=FALSE)) +
  labs(x=NULL, y='value', color=NULL) +
  theme_bw() +
  theme(axis.text.x=element_text(angle=90, vjust=0.5),
        text=element_text(size=12, 'Calibri'),
        legend.direction="horizontal",legend.position="bottom", legend.box="vertical")

plot(p1t)

Here is the data for the plot:

test <- structure(list(loc = structure(c(1L, 1L, 1L, 1L, 1L, 1L, 2L, 
2L, 2L, 2L, 2L, 2L, 3L, 3L, 3L, 3L, 3L, 3L), levels = c("B1", 
"HM1", "HM3"), class = "factor"), DateTime = c("01/03/2022", 
"02/03/2022", "03/03/2022", "01/03/2022", "02/03/2022", "03/03/2022", 
"01/03/2022", "02/03/2022", "03/03/2022", "01/03/2022", "02/03/2022", 
"03/03/2022", "01/03/2022", "02/03/2022", "03/03/2022", "01/03/2022", 
"02/03/2022", "03/03/2022"), calYear = structure(c(1L, 1L, 1L, 
1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L), levels = "2022", class = "factor"), 
    month = structure(c(1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 
    1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L), levels = "3", class = "factor"), 
    spi = c(0.131279514, 0.875832767, 0.105353781, 0.652808322, 
    0.348200666, 0.137788759, 0.546853561, 0.878139205, 0.649630365, 
    0.133656114, 0.960711263, 0.107314452, 0.866935108, 0.401248114, 
    0.553906897, 0.350247914, 0.59256722, 0.609365765), fourLoc = structure(c(1L, 
    1L, 1L, 1L, 1L, 1L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 
    2L, 2L), levels = c("BE", "mere"), class = "factor"), mAODscale = c(0.344703325, 
    0.813991101, 0.50608775, 0.130934881, 0.502777104, 0.67505956, 
    0.440368963, 0.800293223, 0.028270253, 0.416160857, 0.033790935, 
    0.625116508, 0.341240233, 0.437566191, 0.823241792, 0.163872636, 
    0.134161724, 0.233193229), label2 = structure(c(1L, 1L, 1L, 
    1L, 1L, 1L, 2L, 2L, 2L, 2L, 2L, 2L, 3L, 3L, 3L, 3L, 3L, 3L
    ), levels = c("B1", "HM1", "HM3"), class = "factor"), groundSurface = structure(c(1L, 
    1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 2L, 2L, 2L, 1L, 1L, 1L, 2L, 
    2L, 2L), levels = c("ground", "surface"), class = "factor"), 
    maxDate = c(1L, 0L, 0L, 1L, 0L, 0L, 1L, 0L, 0L, 1L, 0L, 0L, 
    1L, 0L, 0L, 1L, 0L, 0L), MinDate = c(0L, 1L, 0L, 0L, 1L, 
    0L, 0L, 1L, 0L, 0L, 1L, 0L, 0L, 1L, 0L, 0L, 1L, 0L), maxDate2 = c(0L, 
    0L, 1L, 0L, 0L, 1L, 0L, 0L, 1L, 0L, 0L, 1L, 0L, 0L, 1L, 0L, 
    0L, 1L), noMaxDate2 = c(0L, 0L, 0L, 0L, 0L, 0L, 0L, 0L, 0L, 
    0L, 0L, 0L, 0L, 0L, 0L, 0L, 0L, 0L), Wtstart = c(1L, 0L, 
    0L, 1L, 0L, 0L, 1L, 0L, 0L, 1L, 0L, 0L, 1L, 0L, 0L, 1L, 0L, 
    0L)), row.names = c(NA, -18L), class = "data.frame")

Answer 1

One option to get rid of the labels for the second variable would be to set by_layer_x=TRUE and to remove the strip background and text using element_blank(). However, this still leaves a blank space in place of the strip texts. Unfortunately I haven't found an option to get rid of that.

library(ggh4x)
#> Loading required package: ggplot2
library(ggplot2)

ggplot(test, aes(x = DateTime, y = mAODscale)) +
  geom_line() +
  facet_wrap2(groundSurface ~ fourLoc,
    drop = FALSE, ncol = 2,
    strip = strip_nested(
      bleed = FALSE,
      by_layer_x = TRUE,
      background_x = list(
        element_rect(),
        element_blank()
      ),
      text_x = list(
        element_text(),
        element_blank()
      )
    )
  ) +
  labs(x = NULL, y = "value", color = NULL) +
  theme_bw() +
  theme(
    axis.text.x = element_text(angle = 90, vjust = 0.5),
    text = element_text(size = 12, "Calibri"),
    legend.direction = "horizontal", legend.position = "bottom", legend.box = "vertical"
  )