extend axis to 0 with geom_density_ridges2

May 11, 2023

The following code produces:

The min value in df is 4, but I would like the breaks and the axis to extend to 0. I do not need the axis to extend past 9. I’ve tried adding limits, but the geom shifts.

The plot is based on an example from the ggridges gallery.

library(tidyverse)
library(ggridges)

df <- structure(list(id = c(1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 6, 6, 7, 
7, 8, 8, 9, 9, 10, 10, 11, 11, 12, 12, 13, 13, 14, 14, 15, 15, 
16, 16, 17, 17, 18, 18, 19, 19, 20, 20, 21, 21, 22, 22, 23, 23, 
24, 24, 25, 25, 26, 26, 27, 27, 28, 28, 29, 29), item = structure(c(1L, 
2L, 1L, 2L, 1L, 2L, 1L, 2L, 1L, 2L, 1L, 2L, 1L, 2L, 1L, 2L, 1L, 
2L, 1L, 2L, 1L, 2L, 1L, 2L, 1L, 2L, 1L, 2L, 1L, 2L, 1L, 2L, 1L, 
2L, 1L, 2L, 1L, 2L, 1L, 2L, 1L, 2L, 1L, 2L, 1L, 2L, 1L, 2L, 1L, 
2L, 1L, 2L, 1L, 2L, 1L, 2L, 1L, 2L), .Label = c("A", "B", "C", 
"D", "E", "F", "G", "H", "I", "J", "K", "L", "M", "N"), class = "factor"), 
    value = c(8, 9, 4, 5, 8, 9, 7, 9, 8, 8, 7, 6, 9, 8, 9, 9, 
    9, 9, 8, 9, 9, 9, 8, 9, 8, 8, 7, 8, 8, 8, 7, 9, 8, 9, 8, 
    9, 9, 9, 9, 9, 8, 9, 9, 9, 9, 7, 9, 9, 8, 9, 8, 9, 7, 9, 
    7, 7, 7, 8)), row.names = c(NA, -58L), class = c("tbl_df", 
"tbl", "data.frame"))

df %>%
  ggplot(aes(x = value, y = item, group = item)) +
    geom_density_ridges2(aes(fill = item), 
                         stat = "binline", 
                         binwidth = 1, 
                         scale = 0.95) +
    geom_text(
      stat = "bin",
      aes(
        y = group + 0.95*stat(count/max(count)),
        label = ifelse(stat(count) > 0, stat(count), "")
      ),
      vjust = -0.5, size = 3, color = "black", binwidth = 1
    ) +
    scale_x_continuous(
      breaks = 0:9, 
      name = "Answer (higher = better)"
    ) +
    scale_y_discrete(
      expand = expansion(add = 2)
    ) +
    scale_fill_viridis_d() +
    labs(
      title = "Example",
      y = NULL
    ) +
    theme_ridges(grid = FALSE) +
    theme(
      axis.title.x = element_text(hjust = 0.5),
      axis.title.y = element_text(hjust = 0.5),
      legend.position = "none",
      plot.title.position = "plot",
      plot.title = element_text(face="bold")
    )

>Solution :

From your question it’s not clear how you tried to set the limits, but taking account of the width of the bars adding limits = c(-.5, 9.5) to scale_x_continuous should do the job:

library(ggridges)
library(ggplot2)

ggplot(df, aes(x = value, y = item, group = item)) +
  geom_density_ridges2(aes(fill = item),
    stat = "binline",
    binwidth = 1,
    scale = 0.95
  ) +
  geom_text(
    stat = "bin",
    aes(
      y = group + 0.95 * stat(count / max(count)),
      label = ifelse(stat(count) > 0, stat(count), "")
    ),
    vjust = -0.5, size = 3, color = "black", binwidth = 1
  ) +
  scale_x_continuous(
    breaks = 0:9,
    name = "Answer (higher = better)",
    limits = c(-.5, 9.5),
  ) +
  scale_y_discrete(
    expand = expansion(add = 2)
  ) +
  scale_fill_viridis_d() +
  labs(
    title = "Example",
    y = NULL
  ) +
  theme_ridges(grid = FALSE) +
  theme(
    axis.title.x = element_text(hjust = 0.5),
    axis.title.y = element_text(hjust = 0.5),
    legend.position = "none",
    plot.title.position = "plot",
    plot.title = element_text(face = "bold")
  )