ggplot中实现图片置于条形图上方及x轴分组标注问题求解

针对两个问题的修改方案如下： #

1. x轴分组标识实现

使用ggh4x包的嵌套坐标轴功能，可以直接按照你的ind字段自动划分前3、后3两组，不需要手动校准坐标位置，适配性更强。

2. 队标完整显示调整

• 调整geom_isotype_col的vjust参数：负值可以让logo向条形图外侧偏移，正数则向条形内部收缩，可根据数值正负设置条件偏移
• 替换原ylim为scale_y_continuous，通过expand参数给y轴上下预留额外空白，避免logo超出绘图区域被裁剪

修改后的完整代码： #

# 提前安装需要的包：install.packages(c("ggh4x", "ggplot2", "ggimage", "magick", "tibble"))
library(ggh4x)
library(ggplot2)
library(ggimage)
library(magick)
library(tibble)

data <- tibble(
  Diff_home_perc = c(-0.3, -0.2, -0.1,-0.05, 0.2, 0.3),
  Team = c("A", "B", "C","D", "E", "F"),
  ind = c("后3名","后3名","后3名","前3名","前3名","前3名"), # 把分组值直接改成要显示的文本
  image = list(
    image_read_svg("https://www.bundesliga.com/assets/clublogo/DFL-CLU-00000G.svg"),
    image_read_svg("https://www.bundesliga.com/assets/clublogo/DFL-CLU-000017.svg"),
    image_read_svg("https://www.bundesliga.com/assets/clublogo/DFL-CLU-000018.svg"),
    image_read_svg("https://www.bundesliga.com/assets/clublogo/DFL-CLU-000003.svg"),
    image_read_svg("https://www.bundesliga.com/assets/clublogo/DFL-CLU-000004.svg"),
    image_read_svg("https://www.bundesliga.com/assets/clublogo/DFL-CLU-00000.svg")
  )
)

ggplot(data, aes(reorder(Team, Diff_home_perc), Diff_home_perc, fill = ind, image = image)) +
  # 替换原ylim，预留上下15%的空白区域放logo
  scale_y_continuous(name = "Difference", limits = c(-0.3, 0.3), expand = expansion(mult = 0.15)) +
  xlab("Team") +
  # vjust按数值正负调整，负值logo往外放
  geom_isotype_col(
    img_height = NULL, img_width = grid::unit(0.5, "null"),
    ncol = 1, nrow = 1, hjust = 0.5, 
    vjust = ifelse(data$Diff_home_perc > 0, -0.1, 1.1)
  ) +
  # 添加嵌套分组轴
  guides(x = "axis_nested") +
  guides(fill = "none") +
  theme_minimal() +
  theme(
    plot.title = element_blank(),
    axis.title.x = element_blank(),
    text = element_text(size=15),
    legend.title = element_blank(),
    legend.position="none",
    # 调整嵌套轴的样式
    ggh4x.axis.nestline.x = element_line(linewidth = 1),
    ggh4x.axis.nesttext.x = element_text(colour = "black")
  )

如果不想安装额外的包，也可以用annotate函数手动在x轴对应位置添加文本和分割线，只要计算好两组的x轴坐标位置（后3名对应x=1.5位置，前3名对应x=4.5位置）即可。

内容的提问来源于stack exchange，提问作者user15077915