如何在绘图轴上显示组变量以及数字中点？

Question

我有一些数据，这是其中的一个子集：

MyDataToSO <- data.frame(Age = c(2, 7, 12, 16, 21),
                     AgeGroup = c("0-4 years", "5-9 years", "10-14 years", "15-17 years", "18-24 years"),
                     Proportion = c(0.963, 0.965, 0.925, 0.701, 0.422))

我希望绘制数据，以便在 x 轴上获得相关的 AgeGroup 显示在 Age 刻度线下方。 Age 值是 AgeGroup 类别的中点。

我有我想要的情节，除了在 x 轴的相关部分下添加 AgeGroup 波段：

ggplot(data = MyDataToSO, aes(x = Age, y = Proportion)) +
geom_point() +
geom_point(data = subset(MyDataToSO, Age %in% c(16,21)), color = "green")
scale_x_continuous(breaks=seq(0, 30, by = 10)) +
labs(x = "Age group", y = "Proportion")

该图表有效，在正确的位置显示了相关的Age，但没有迹象表明Age 的值来自年龄组。

我认为通过在 x 轴上添加第二个标签来显示这一点会很有用，因此生成的 x 轴看起来有点像：

|
|______________________________...
      |         |         |    ...
      2         7         12   ...
|__________|_________|_________|...
 "0-4 years  5-9 years  10-14 years"...

我需要稍微调整一下字体大小才能使其正常工作。我还想让年龄组线条比正常打印更轻（例如，不透明比正常少 25%）。我在年龄组标签周围加上了引号，以阻止 SO 将每个数字显示为橙色数字。

如何将此信息添加到我的图表中？我搜索了二级标签，但只找到了与二级轴相关的问题。如您所见，所需的分组信息存储在AgeGroup 中，因此我“只”需要从那里提取相关值。

编辑：我加载了ggh4x 包，ggplot 代码现在是这样的：

ggplot(data = MyDataToSO, aes(interaction(Age, AgeGroup), Proportion)) +
geom_point() +
geom_point(data = subset(MyDataToSO, Age %in% c(16,21)), color = "green")
scale_x_continuous(breaks=seq(0, 30, by = 10)) +
guides(x = "axis_nested") +
labs(x = "Age group", y = "Proportion")

但它给出了一个错误，因为 x 轴是连续的。

编辑 2：绿点是插值。我现在有 17 到 20 岁的插值。但这些重复相同的 AgeGroup 标签。这是个问题吗？

Answer 1

另一种方法是添加注释，关闭剪辑，并在轴文本和轴标题之间放置更多空间，如下所示：

ggplot(data = MyDataToSO, aes(x = Age, y = Proportion)) +
  geom_point() +
  geom_point(data = subset(MyDataToSO, Age %in% c(16,21)), color = "green") +
scale_x_continuous(breaks=seq(0, 30, by = 10)) +
  labs(x = "Age group", y = "Proportion") +
  annotate("rect", fill = "gray80",
           xmin = c(0, 5, 10, 15, 18),
           xmax = c(5, 10, 15, 18, 24) - 0.2,
           ymin = 0.28, ymax = 0.32) +
  annotate("text", size = 3,
           x = MyDataToSO$Age + 0.5,
           y = 0.3, label = MyDataToSO$AgeGroup) +
  coord_cartesian(ylim = c(0.4, 1), clip = "off") +
  theme(axis.title.x = element_text(margin = margin(t = 25, r = 0, b = 0, l = 0)))

编辑：根据我对附加评论的理解，现在将 15:21 分开。

MyDataToSO <- data.frame(Age = c(2, 7, 12, 15:21),
                         AgeGroup = c("0-4 years", "5-9 years", "10-14 years", 15:21),
                         Proportion = c(0.963, 0.965, 0.925, 0.701, .740, .677, .610, .540, .470, .401))


ggplot(data = MyDataToSO, aes(x = Age, y = Proportion)) +
  geom_point() +
  geom_point(data = subset(MyDataToSO, Age %in% c(16,21)), color = "green") +
  scale_x_continuous(breaks=seq(0, 30, by = 10)) +
  labs(x = "Age group", y = "Proportion") +
  annotate("rect", fill = "gray80",
           xmin = c(0, 5, 10, 15:21) - 0.4,
           xmax = c(5, 10, 15, 16:22) - 0.6,
           ymin = 0.28, ymax = 0.32) +
  annotate("text", size = 3,
           x = MyDataToSO$Age,
           y = 0.3, label = MyDataToSO$AgeGroup) +
  coord_cartesian(ylim = c(0.4, 1), clip = "off") +
  theme(axis.title.x = element_text(margin = margin(t = 25, r = 0, b = 0, l = 0)))

Answer 2

ggh4x 包具有扩展 ggplot2 以更自动的方式执行此操作的功能（https://cran.r-project.org/web/packages/ggh4x/vignettes/PositionGuides.html，向下滚动到“嵌套关系”）。

Answer 3

一种快速简便的方法是创建一个列表或变量，在其中附加来自MyDataToSO$Age 和MyDataToSO$AgeGroup 的值，并用两个回车符（即\n）分隔。您将该列表/变量传递给 scale_x_continuous 的“标签”指令。

library(tidyverse)

MyDataToSO <- tibble(Age = c(2, 7, 12, 16, 21),
                     AgeGroup = c("0-4 years", "5-9 years", "10-14 years", "15-17 years", "18-24 years"),
                     Proportion = c(0.963, 0.965, 0.925, 0.701, 0.422)) %>% 
 mutate(custom_labels = paste0(Age, "\n\n", AgeGroup)) ## This is where you create the custom labels

ggplot(data = MyDataToSO, aes(x = Age, y = Proportion)) +
    geom_point() +
    geom_point(data = subset(MyDataToSO, Age %in% c(16,21)), color = "green") + 
scale_x_continuous(breaks=seq(0, 30, by = 10)) +
    labs(x = "Age group", y = "Proportion") +
    scale_x_continuous(breaks = c(MyDataToSO$Age), ## Here you pass the relevant ages. Should be aligned with the custom_labels
                       labels = c(MyDataToSO$custom_labels)) ## Here you pass the custom label balues