R ggplot2在geom_hline的ggtext周围绘制一个标签框。

Question

根据下面的数据和代码，我如何添加一个标签边界框(类似于您将鼠标悬停在一条线上，并且该值通过ggplotly显示在边界框中)，如下面所需的输出所示。

请注意，由于一些未知的原因，平均水平线显示为black，尽管在图例中它是blue (如代码中所定义的)。

期望产出：

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样本数据(AvgTMeanYear)：

structure(list(year = 1980:2021, AvgTMean = c(24.2700686838937, 
23.8852956598276, 25.094446596092, 24.1561175050287, 24.157183605977, 
24.3047482638362, 24.7899738481466, 24.5756232655603, 24.5833086228592, 
24.7344695534483, 25.3094451071121, 25.2100615173707, 24.3651692293534, 
24.5423890611494, 25.2492166633908, 24.7005097837931, 24.2491591827443, 
25.0912281781322, 25.0779264303305, 24.403294248319, 24.4983991453592, 
24.4292324356466, 24.8179824927011, 24.7243948463075, 24.5086534543966, 
24.2818632071983, 24.4567195220259, 24.8402224356034, 24.6574465515086, 
24.5440715673563, 23.482670620977, 24.9979594684914, 24.5452453980747, 
24.9271462811494, 24.7443215819253, 25.8929839790805, 25.1801908261063, 
25.2079308058908, 25.0722425561207, 25.4554644289799, 25.4548979078736, 
25.0756772250287)), class = c("tbl_df", "tbl", "data.frame"), row.names = c(NA, 
-42L))

代码：

    AvgTMeanYear %>%
     group_by(year) %>%
  summarise(tmean = mean(AvgTMean,na.rm = TRUE)) %>%
  ggplot(aes(x= year, y=tmean)) +
  geom_line(aes(color = "Historic Trend"), stat = "identity") +
  geom_hline(yintercept = mean(AvgTMeanYear$tmean), aes(color="Average Temperature")) +
  scale_colour_manual(values = c("Average Temperature" = "blue","Historic Trend" = "black"), name = "Legend") +
  xlab("Year") +
  ylab("Avg. Mean T. (\u00B0C)") +
  ggtitle("Temperature Trend 1980-2021") +
  geom_text(aes(x = 1980 , y = 24.6, label = "24.47 \u00B0C"))

Answer 1

让我们来处理所有的问题。

1. geom_label在文本周围画一个框。
2. 我们可以通过为geom_hline强制使用不同的数据来解决蓝线问题。Tbh，我不完全确定为什么您最初的文字方法不起作用，但这个方法有效。
3. 由于标签的位置，我们可以关闭裁剪，以确保它都是可见的。(这可能并不总是一个问题。)(这也可以通过使用hjust=和yjust=进行手动控制，或者使用用于动态/随机“强迫”数据的ggrepel包来解决。)

AvgTMeanYear %>%
  group_by(year) %>%
  summarise(AvgTMean = mean(AvgTMean ,na.rm = TRUE)) %>%
  ggplot(aes(x= year, y=AvgTMean)) +
  geom_line(aes(color = "Historic Trend"), stat = "identity") +
  # UPDATED to add new data and put yint inside aes
  geom_hline(aes(yintercept = y, color = "Average Temperature"),
             data = data.frame(col="Average Temperature", y=24.4)) +
  scale_colour_manual(values = c("Average Temperature" = "blue","Historic Trend" = "black"), name = "Legend") +
  xlab("Year") +
  ylab("Avg. Mean T. (\u00B0C)") +
  ggtitle("Temperature Trend 1980-2021") +
  # UPDATED to change geom_text to geom_label
  geom_label(aes(x = 1980 , y = 24.6, label = "24.47 \u00B0C")) +
  # ADDED
  coord_cartesian(clip = "off")

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Answer 2

你在找geom_label()吗？例如,

ggplot(mtcars, aes(wt, mpg)) +
  geom_point() +
  geom_label(aes(x = 2.62, y = 21, label = "Mazda RX4"))