R + ggplot2 =>添加标签在facet饼图[重复]

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这个问题在这里已有答案：

• ggplot, facet, piechart: placing text in the middle of pie chart slices 4 answers
• ggplot，facet，piechart：将文本放在饼图中间切片4个答案

I want to add data labels on faceted pie char.
Maybe someone can can help me.

我想在分面饼图上添加数据标签。也许有人可以帮助我。

My data:

我的数据：

year <- c(1,2,1,2,1,2)
prod <- c(1,1,2,2,3,3)
quantity <- c(33,50,33,25,34,25)

df <- data.frame(year, prod, quantity)
rm(year, prod, quantity)

Code:

码：

library(ggplot2)

# center's calculated by hand
centr2 <- c(16, 25, 49, 62.5, 81, 87.5)

ggplot(data=df, aes(x=factor(1), y=quantity, fill=factor(prod))) +
    geom_bar(stat="identity") +
    geom_text(aes(x= factor(1), y=centr2, label = df$quantity), size=10) +
    facet_grid(facets = .~year, labeller = label_value) +
    coord_polar(theta = "y")

And my result is:

我的结果是：

If I remove coord_polar(theta = "y"), I will have the following plot:

如果我删除coord_polar（theta =“y”），我将得到以下图：

And now it is clear for me, why my data labels did not match.
But I don't know how to fix it.

现在我很清楚，为什么我的数据标签不匹配。但我不知道如何解决它。

I read:
1. Place labels on Pie Chart
2. Add text to ggplot with facetted densities
3. Pie plot getting its text on top of each other

我读到：1。在饼图上放置标签2.在带有刻面密度的ggplot中添加文本3.饼图将其文本放在彼此的顶部

But didn't find the answer.

但没有找到答案。

1 个解决方案

#1

I would approach this by defining another variable (which I call pos) in df that calculates the position of text labels. I do this with dplyr but you could also use other methods of course.

我会通过在df中定义另一个变量（我称之为pos）来计算文本标签的位置。我用dplyr做这个，但你当然也可以使用其他方法。

library(dplyr)
library(ggplot2)

df <- df %>% group_by(year) %>% mutate(pos = cumsum(quantity)- quantity/2)

ggplot(data=df, aes(x=factor(1), y=quantity, fill=factor(prod))) +
  geom_bar(stat="identity") +
  geom_text(aes(x= factor(1), y=pos, label = quantity), size=10) +  # note y = pos
  facet_grid(facets = .~year, labeller = label_value) +
  coord_polar(theta = "y")