R:ggplot堆积条形图,y轴计数,但百分比为标签

Question

我正在寻找一种方法来标记带百分比的堆积条形图,而y轴显示原始计数(使用ggplot).这是没有标签的情节的MWE:

library(ggplot2)
df <- as.data.frame(matrix(nrow = 7, ncol= 3,
                       data = c("ID1", "ID2", "ID3", "ID4", "ID5", "ID6", "ID7",
                                "north", "north", "north", "north", "south", "south", "south",
                                "A", "B", "B", "C", "A", "A", "C"),
                      byrow = FALSE))

colnames(df) <- c("ID", "region", "species")

p <- ggplot(df, aes(x = region, fill = species))
p  + geom_bar()

我有一个更大的桌子,R很好地计算每个地区的不同物种.现在,我想展示原始计数值(最好在y轴上)和百分比(作为标签)来比较区域之间物种的比例.

我试了很多东西,geom_text()但我认为与其他问题(例如这一个)的主要区别在于

• 我没有y值的单独列(它们只是每个区域不同物种的数量)和
• 我需要每个区域的标签总和达到100%(因为它们被认为代表单独的人口),而不是整个情节的所有标签.

任何帮助深表感谢!!

Answer 1

正如@Gregor所提到的,分别汇总数据,然后将数据汇总提供给ggplot.在下面的代码中,我们使用动态dplyr创建摘要:

library(dplyr)

ggplot(df %>% count(region, species) %>%    # Group by region and species, then count number in each group
         mutate(pct=n/sum(n),               # Calculate percent within each region
                ypos = cumsum(n) - 0.5*n),  # Calculate label positions
       aes(region, n, fill=species)) +
  geom_bar(stat="identity") +
  geom_text(aes(label=paste0(sprintf("%1.1f", pct*100),"%"), y=ypos))

更新:使用dplyr0.5及更高版本,您不再需要提供y值来居中每个栏中的文本.相反,你可以使用position_stack(vjust=0.5):

ggplot(df %>% count(region, species) %>%    # Group by region and species, then count number in each group
         mutate(pct=n/sum(n)),              # Calculate percent within each region
       aes(region, n, fill=species)) +
  geom_bar(stat="identity") +
  geom_text(aes(label=paste0(sprintf("%1.1f", pct*100),"%")), 
            position=position_stack(vjust=0.5))