如何在geom_density_ridges2中将X轴扩展至0且不偏移图形

你碰到的问题根源是，直接给X轴加limits后，stat="binline"和geom_text的分箱统计没对齐新的X轴范围，导致图形偏移。解决办法是给分箱统计指定从0开始的边界，同时扩展X轴范围，修改后的完整代码如下：

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,
                         boundary = 0) +  # 指定分箱从0开始，对齐X轴新范围
    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,
      boundary = 0  # 文本统计用相同分箱边界，避免偏移
    ) +
    scale_x_continuous(
      breaks = 0:9, 
      limits = c(0,9),  # 扩展X轴到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")
    )

核心修改说明： #

• 给geom_density_ridges2和geom_text的分箱统计都加上boundary = 0：让分箱区间从0开始（0-1、1-2……8-9），保证图形和文本的位置与新X轴范围完全对齐，不会偏移。
• 在scale_x_continuous里添加limits = c(0,9)：正式把X轴的范围扩展到0-9，同时保留0到9的刻度。

修改后，X轴会完整显示0到9的刻度，0-3的区间因为没有数据，不会显示柱子和文本，完全符合需求。

内容的提问来源于stack exchange，提问作者Eric Green