Tagging fails when patching more than 2 nested patchwork

[hummuscience]

I went with the example form the documentation.

library(ggplot2)
p1 <- ggplot(mtcars) + 
  geom_point(aes(mpg, disp)) 

p2 <- ggplot(mtcars) + 
  geom_boxplot(aes(gear, disp, group = gear)) 

p3 <- ggplot(mtcars) + 
  geom_point(aes(hp, wt, colour = mpg)) 

p4 <- ggplot(mtcars) + 
  geom_bar(aes(gear)) + 
  facet_wrap(~cyl)

p5 <- ggplot(mtcars) + 
  geom_bar(aes(vs)) + 
  facet_wrap(~cyl) 

The below works

(p1 + p2) / p3 +
  plot_annotation(tag_levels = 'A')

This doesn't

p1 |
  (p2 / p3) |
  (p4 / p5) +
  plot_annotation(tag_levels = 'A')

R version 4.3.0 (2023-04-21)
Platform: x86_64-pc-linux-gnu (64-bit)
Running under: Ubuntu 20.04.6 LTS

Matrix products: default
BLAS:   /usr/lib/x86_64-linux-gnu/blas/libblas.so.3.9.0 
LAPACK: /usr/lib/x86_64-linux-gnu/lapack/liblapack.so.3.9.0

locale:
 [1] LC_CTYPE=en_US.UTF-8       LC_NUMERIC=C              
 [3] LC_TIME=de_DE.UTF-8        LC_COLLATE=en_US.UTF-8    
 [5] LC_MONETARY=de_DE.UTF-8    LC_MESSAGES=en_US.UTF-8   
 [7] LC_PAPER=de_DE.UTF-8       LC_NAME=C                 
 [9] LC_ADDRESS=C               LC_TELEPHONE=C            
[11] LC_MEASUREMENT=de_DE.UTF-8 LC_IDENTIFICATION=C       

time zone: Europe/Berlin
tzcode source: system (glibc)

attached base packages:
[1] stats     graphics  grDevices utils     datasets  methods   base     

other attached packages:
[1] patchwork_1.1.2 ggplot2_3.4.2  

loaded via a namespace (and not attached):
 [1] labeling_0.4.2   utf8_1.2.3       R6_2.5.1         tidyselect_1.2.0
 [5] farver_2.1.1     magrittr_2.0.3   gtable_0.3.3     glue_1.6.2      
 [9] tibble_3.2.1     pkgconfig_2.0.3  generics_0.1.3   dplyr_1.1.2     
[13] lifecycle_1.0.3  cli_3.6.1        fansi_1.0.4      scales_1.2.1    
[17] grid_4.3.0       vctrs_0.6.2      withr_2.5.0      compiler_4.3.0  
[21] tools_4.3.0      munsell_0.5.0    pillar_1.9.0     colorspace_2.1-0
[25] rlang_1.1.1  

[thomasp85]

This is a hard to debug issue with operator precedence. The plot_annotation() is added to the (p4/p5) rather than to the full plot because | has lower precedence than +. As plot_annotation()(for now) only have an effect on the top level patchwork it seems to vanish.

You can get the correct look by enclosing the whole assembly in parentheses before adding annotation:

library(ggplot2)
library(patchwork)

p1 <- ggplot(mtcars) + 
  geom_point(aes(mpg, disp)) 

p2 <- ggplot(mtcars) + 
  geom_boxplot(aes(gear, disp, group = gear)) 

p3 <- ggplot(mtcars) + 
  geom_point(aes(hp, wt, colour = mpg)) 

p4 <- ggplot(mtcars) + 
  geom_bar(aes(gear)) + 
  facet_wrap(~cyl)

p5 <- ggplot(mtcars) + 
  geom_bar(aes(vs)) + 
  facet_wrap(~cyl) 

(p1 |
  (p2 / p3) |
  (p4 / p5)) +
  plot_annotation(tag_levels = 'A')

^{Created on 2023-08-09 by the reprex package (v2.0.1)}