R 在第一个栏或更高位置写入组标签，而不是图例

我有一个包含以下数据的堆叠条形图

df <- expand.grid(name = c("oak","birch","cedar"),
    sample = c("one","two"),
    type = c("sapling","adult","dead"))
df$count <- sample(5:200, size = nrow(df), replace = T)

它产生：

出现两到三个问题：

如何使标签仅显示在顶部栏中

如何使标签显示在条形图部分的中心

可选：如何使标签显示在通过箭头连接到其分区的顶部栏的顶部

---

上面有一个链接。那会对你有帮助的。在这里，我有另一个建议

set.seed(123)
df <- expand.grid(name = c("oak","birch","cedar"),
                  sample = c("one","two"),
                  type = c("sapling","adult","dead"))
df$count <- sample(5:200, size = nrow(df), replace = T)

### Arrange a data frame (summing up sample one and two)
library(dplyr)
ana <- df %>%
        group_by(name, type) %>%
        summarise(total = sum(count))

# Draw a figure once        
bob <- ggplot(ana, aes(x = name, y = total, fill = type)) +
       geom_bar(stat = "identity", position = "stack")

# Get a data frame for ggplot      
cathy <- ggplot_build(bob)$data[[1]]

# calculate text position & add text labels
cathy$y_pos <- (cathy$ymin + cathy$ymax) / 2
cathy$label <- rep(c("sampling", "adult", "dead"), times = 3)

# Subset the data for labeling for the top bar
dan <- cathy[c(7:9), ]

# Draw a figure again
bob + 
annotate(x = dan$x, y = dan$y_pos, label = dan$label, geom="text", size=3) +
coord_flip()

set.seed（123）
df应帮助您进行定位；对于仅标记选定的值，我将引入一个新的变量标签，该标签的类型值为cedar，而其他树为空。我猜想，不可能将标签放在顶部栏的上方，并通过箭头将其组合到其栏部分？MS Excel可以（尽管不一定适用于堆叠的条形图）。@MERose您可以将图例移动到顶部位置。但是我不认为
ggplot
有箭头的东西。
set.seed(123)
df <- expand.grid(name = c("oak","birch","cedar"),
                  sample = c("one","two"),
                  type = c("sapling","adult","dead"))
df$count <- sample(5:200, size = nrow(df), replace = T)

### Arrange a data frame (summing up sample one and two)
library(dplyr)
ana <- df %>%
        group_by(name, type) %>%
        summarise(total = sum(count))

# Draw a figure once        
bob <- ggplot(ana, aes(x = name, y = total, fill = type)) +
       geom_bar(stat = "identity", position = "stack")

# Get a data frame for ggplot      
cathy <- ggplot_build(bob)$data[[1]]

# calculate text position & add text labels
cathy$y_pos <- (cathy$ymin + cathy$ymax) / 2
cathy$label <- rep(c("sampling", "adult", "dead"), times = 3)

# Subset the data for labeling for the top bar
dan <- cathy[c(7:9), ]

# Draw a figure again
bob + 
annotate(x = dan$x, y = dan$y_pos, label = dan$label, geom="text", size=3) +
coord_flip()