无法使用R ggplot2向饼图添加标签

Question

有人可以向我解释为什么我不能在此饼图中添加标签吗？

> dput (test)
structure(list(Status = c("Isolamento domiciliare", "Ricoverati con sintomi", 
"Terapia intensiva", "Deceduti", "Dimessi guariti"), label = c("69.03%", 
"17.70%", "12.39%", "0.88%", "0.00%"), value = c(78, 20, 14, 
1, 0)), row.names = c(NA, -5L), class = c("tbl_df", "tbl", "data.frame"
))

这是我用于绘图的代码：

ggplot(test, aes(x="", y=value, fill=Status)) +
    geom_bar(stat="identity", width=1, color="white") +
    coord_polar("y", start=0) +
    theme_void()+ labs(fill = "Situazione attuale")

提前感谢

Answer 1

对于极坐标，您需要为标签定义一些位置。在这里，我们可以将这些位置定义为：

library(dplyr)
test2 <- test %>% 
  arrange(desc(Status)) %>%
  mutate(percent = value / sum(value)*100) %>%
  mutate(ypos = cumsum(percent)-0.5*percent)

# A tibble: 5 x 5
  Status                 label  value percent  ypos
  <chr>                  <chr>  <dbl>   <dbl> <dbl>
1 Terapia intensiva      12.39%    14  12.4    6.19
2 Ricoverati con sintomi 17.70%    20  17.7   21.2 
3 Isolamento domiciliare 69.03%    78  69.0   64.6 
4 Dimessi guariti        0.00%      0   0     99.1 
5 Deceduti               0.88%      1   0.885 99.6 

然后，您可以将此标签添加到绘图中。但是，由于您的值非常接近（0和0.88％），因​​此这些值可能会重叠。因此，您可以改用geom_text_repel，但它也会更改其他标签的位置。因此，我决定将大值添加为常规geom_text，将小值添加为geom_text_repel，您将获得以下内容：

library(ggrepel)
library(ggplot2)

ggplot(test2,aes(x="", y=percent, fill=Status)) +
  geom_bar(stat="identity", width=1, color="white") +
  coord_polar("y", start=0) +
  theme_void()+ labs(fill = "Situazione attuale")+
  geom_text(data = subset(test2, value >2), aes(label = label, y = ypos))+
  geom_text_repel(data = subset(test2, value <2), aes(label = label, y = ypos))

---

编辑：将标签放置在饼图之外

如果您想将标签放置在饼图之外，则可以将它们的x值赋予以下属性：

ggplot(test2,aes(x=1, y=percent, fill=Status)) +
  geom_bar(stat="identity", width=1, color="white") +
  coord_polar("y", start=0) +
  theme_void()+ labs(fill = "Situazione attuale")+
  geom_text(data = subset(test2, value >2), aes(label = label, y = ypos, color = Status), show.legend = FALSE, x= 1.75)+
  geom_text_repel(data = subset(test2, value <2), aes(label = label, y = ypos, color = Status), x = 1.75, show.legend = FALSE)+
  expand_limits(x = c(1,1.8))

它回答了您的问题吗？