add a horizontal line in a ggplot Likert bar

Question

I have a ggplot object named p :

library(dplyr, warn = FALSE)

likert_levels <- c(
  "Strongly disagree",
  "Disagree",
  "Neither agree nor disagree",
  "Agree",
  "Strongly agree"
)

df <-
  tibble(
    "there is an argument sort_prop_include_center that could be set up to TRUE in order to include half of the centered level when sorting data" = sample(likert_levels, 150, replace = TRUE),
    "Similarly, the argument totals_include_center allows you to include half of the centered level into the left and the right totals" = sample(likert_levels, 150, replace = TRUE, prob = 5:1),
    "Here is one possible option which uses reorder and an ifelse to reorder the variable mapped on y using the counts (aka the sum) of Strictly disagree " = sample(likert_levels, 150, replace = TRUE, prob = 1:5),
    "and disagree answers. Under the hood ggstats::gglikert reshape the data to long where the question id's are stored in a column named .question and the answers in a column named .answer:" = sample(likert_levels, 150, replace = TRUE, prob = 1:5),
    "They used sampling data and create a data frame called df. I am using the same as given in the link.(the df not the df_dk). Ok, if i run in R the following code :" = sample(c(likert_levels, NA), 150, replace = TRUE),
    "proportion of answers higher than the centered level. I want the plot to be sorted according to very left proportions that are the combination (sum) of the two lower levels. (i.e Respectively the percentages on the very right in the sum of the two lower categories. )" = sample(likert_levels, 150, replace = TRUE, prob = c(1, 0, 1, 1, 0))
  ) %>%
  mutate(across(everything(), ~ factor(.x, levels = likert_levels)))



library(ggplot2)
library(ggstats)

p = ggstats::gglikert(df) +
  aes(y = reorder(.question,
                  ifelse(
                    .answer %in% c("Strongly disagree", "Disagree"),
                    1, 0
                  ),
                  FUN = sum
  ))+ theme(axis.text.y = element_text(size = 8))

I want to add horizontally two lines:

1. line that will separate the y axis as now is sorted in a decreasing order at 20% and

2. a second line at 50 %.

additionally I want a text from 0 to 20% to write "warning zone" inside the panel (plot) at the left and from 20% to 50% "so-so" and from 50% to 100% to write "no warning zone"

How can I achieve this using ggplot2 package in R in this sorted scale Likert plot ?

Answer 1

To determine the position of the lines and text, save the original plot as p, then use layer_data(p, 3) to inspect the data (specifically the x, y and label columns) behind the 3rd ggplot layer (the one with the text percentages).

Then add the geom_hline and annotates with the determined positions.

library(dplyr, warn = FALSE)
library(ggplot2)
library(ggstats)
library(purrr)

likert_levels <- c(
  "Strongly disagree",
  "Disagree",
  "Neither agree nor disagree",
  "Agree",
  "Strongly agree"
)

df <-
  tibble(
    "there is an argument sort_prop_include_center that could be set up to TRUE in order to include half of the centered level when sorting data" = sample(likert_levels, 150, replace = TRUE),
    "Similarly, the argument totals_include_center allows you to include half of the centered level into the left and the right totals" = sample(likert_levels, 150, replace = TRUE, prob = 5:1),
    "Here is one possible option which uses reorder and an ifelse to reorder the variable mapped on y using the counts (aka the sum) of Strictly disagree " = sample(likert_levels, 150, replace = TRUE, prob = 1:5),
    "and disagree answers. Under the hood ggstats::gglikert reshape the data to long where the question id's are stored in a column named .question and the answers in a column named .answer:" = sample(likert_levels, 150, replace = TRUE, prob = 1:5),
    "They used sampling data and create a data frame called df. I am using the same as given in the link.(the df not the df_dk). Ok, if i run in R the following code :" = sample(c(likert_levels, NA), 150, replace = TRUE),
    "proportion of answers higher than the centered level. I want the plot to be sorted according to very left proportions that are the combination (sum) of the two lower levels. (i.e Respectively the percentages on the very right in the sum of the two lower categories. )" = sample(likert_levels, 150, replace = TRUE, prob = c(1, 0, 1, 1, 0))
  ) %>%
  mutate(across(everything(), ~ factor(.x, levels = likert_levels)))

# function to save retyping common arguments
anno <- partial(annotate, "text", x = -1, angle = 90, size = 5, fontface = "bold")

gglikert(df) +
  aes(y = reorder(.question,
                  ifelse(
                    .answer %in% c("Strongly disagree", "Disagree"),
                    1, 0
                  ),
                  FUN = sum, decreasing = TRUE
  )) +
  theme(axis.text.y = element_text(size = 8)) + 
  geom_hline(yintercept = c(1.5, 5.5), linetype = "dashed", colour = "grey20") +
  anno(y = 1, label = "warning\nzone", color = "#A6611A") +
  anno(y = 3.5, label = "so-so", color = "black") +
  anno(y = 6, label = "no warning\nzone", color = "#018571") +
  labs(y = NULL)

^{Created on 2024-04-21 with reprex v2.1.0}