如何在 ggplot2 中围绕轴刻度标签创建一个框？

出于多种原因，我试图复制下面所示的怪诞情节。它违反了良好数据可视化的许多规则，因此出于培训目的，我的目标是使用ggplot2并解构它——一次删除或修改一个选择不当的功能。使用底部复制的数据和图下方的代码，我已经接近目标，但无法弄清楚如何包含一项显着功能。

问题：有没有办法重现三个刻度标签周围的黑色阴影矩形？ （如果是这样，则可以直接创建另一个因子变量来识别这三个标签并将其字体更改为白色。）

ggplot(plotpg19, aes(x = risks, y = scores, fill = colors)) +
  geom_bar(stat = "identity", width = 0.6) +
  scale_fill_manual(values = c("grey50", "deepskyblue2", "mediumorchid3", "gold")) +
  geom_text(aes(label = scores), hjust = -0.4, size = 8, face = "bold") +
  coord_flip() +
  theme_bw() + labs(x = NULL, y = NULL) +
  theme(panel.grid.major = element_blank()) +
  guides(fill = FALSE) +
  scale_y_continuous(breaks = seq(0, 100, 20), labels = seq(0, 100, 20), expand = c(0, 0)) +
  theme(
    panel.border = element_blank(),
    axis.line = element_line(colour = "black", size = 5, linetype = "solid", lineend = "square")
  ) +
  geom_hline(yintercept = seq(0, 80, 10), colour = "grey30", size = .5, linetype = "dotted") +
  theme(axis.line.x = element_blank()) # to get a single axis border, must format both and then blank one

顺便说一句，这个问题使用符号作为刻度标签 https://stackoverflow.com/questions/8905101/how-can-i-use-a-graphic-imported-with-grimport-as-axis-tick-labels-in-ggplot2-u可能会使用以下内容提供一些见解grImport包，但它的教导超出了我的范围，我正在寻找指定刻度标签周围的阴影框。

plotpg19 <- structure(list(risks.format = structure(c(2L, 3L, 1L, 4L, 5L, 
  7L, 8L, 6L), .Label = c("Geographic locations in which\n                                 the company operates", 
  "Inadequate resources for anti-bribery/\ncorruption compliance activities", 
  "Industries/sector(s) in which\n                                 the company operates", 
  "Lack of anti-bribery/corruption training\n                                 or awareness within the business", 
  "Lack of understanding\n                                 by top executives", 
  "Other", "Rogue employees", "Third parties/associates\n                                 acting on our behalf"
  ), class = "factor"), risks = structure(c(8L, 7L, 6L, 5L, 4L, 
  3L, 2L, 1L), .Label = c("Other", "Third parties/associates acting on our behalf", 
  "Rogue employees", "Lack of understanding by top executives", 
  "Lack of anti-bribery/corruption training or awareness within the business", 
  "Geographic locations in which the company operates", "Industries/sector(s) in which the company operates", 
  "Inadequate resources for anti-bribery/corruption compliance activities"
  ), class = "factor"), scores = c(15, 28, 71, 16, 5, 48, 55, 2
  ), colors = c("A", "A", "B", "A", "A", "C", "D", "A")), .Names = c("risks.format", 
  "risks", "scores", "colors"), row.names = c(NA, -8L), class = "data.frame")

我认为最好的选择是在刻度标签的位置创建视口，并在那里绘制黑色矩形和白色文本。例如：

vp1 <- viewport(x = 0.225, y = 0.55, width = 0.45, height = 0.07)
grid.rect(gp = gpar(fill="black"), vp = vp1)
grid.text("Lack of anti-bribery corruption training or awareness within the business", gp=gpar(col="white", cex = 0.6), vp = vp1)

Will give you the graph below: