Remove segment around label-CodePudding

Consider this plot:

seg <- data.frame(x = 1, xend = 1, y = 2, yend = 3)

ggplot(seg)  
  aes(x = x, xend = xend, y = y, yend = yend)  
  geom_segment()  
  geom_text(aes(y = (y   yend) / 2), label = "Hello", size = 10)

Is there an easy way to remove the part of the segment that overlaps with the text?

I tried using geom_label but I still want the background to be the same, just the other objects to be removed around the text. I also tried with geomtextpath but I can't get the text to be horizontal. Any ideas?

Looking for something like this:

CodePudding user response：

I wouldn't say the following is 'easy', but you can use the {ggfx} package to put an inverted mask on the segment that corresponds with a textbox.

library(ggplot2)
library(ggfx)

seg <- data.frame(x = 1, xend = 1, y = 2, yend = 3)

ggplot(seg)  
  aes(x = x, xend = xend, y = y, yend = yend)  
  # Adding a label-textbox as mask ensures appropriate window-agnostic size
  # Just make sure the aesthetics are the same as the geom_text later
  as_reference(
    geom_label(aes(y = (y   yend) / 2), label = "Hello", size = 10),
    id = "textbox"
  )  
  # Plot the masked bit
  with_mask(
    geom_segment(),
    mask = ch_alpha("textbox"), invert = TRUE
  )  
  # On top of the mask
  geom_text(aes(y = (y   yend) / 2), label = "Hello", size = 10)

^{Created on 2022-10-14 by the reprex package (v2.0.1)}

CodePudding user response：

An option could be using ggplot_build to modify the distance of your geom_segment by creating two separate segments like this:

seg <- data.frame(x = 1, xend = 1, y = 2, yend = 3)

library(ggplot2)
library(dplyr)
p <- ggplot(seg)  
  aes(x = x, xend = xend, y = y, yend = yend)  
  geom_segment()  
  geom_text(aes(y = (y   yend) / 2), label = "Hello", size = 10)

q <- ggplot_build(p)

q$data[[1]] <- q$data[[1]] %>%
  bind_rows(q$data[[1]]) %>%
  mutate(y = c(2, 2.55),
         yend = c(2.45, 3))

q <- ggplot_gtable(q)

plot(q)

^{Created on 2022-10-15 with reprex v2.0.2}