ggplot2条形图添加数据标签

---

title: "添加数据标签"
author: "wintryheart"
date: "2019/7/21"
output: html_document

---

knitr::opts_chunk$set(echo = TRUE)

数据

library(reshape2)
y2000 <- c(77.17, 11.46, 11.38)
y2010 <- c(68.23, 16.4,15.37)
nesttype <- c("与子女生活","独居空巢","夫妻空巢")
emptynest <- data.frame(nesttype,y2000, y2010)
knitr::kable(emptynest)
emptynest2 <- melt(emptynest, id.vars = "nesttype", variable.name = "year", value.name = "proportion")
with(emptynest2, 
 nesttype <- factor(nesttype, levels = c("与子女生活","夫妇空巢","独居空巢"), labels = c("与子女生活","夫妇空巢","独居空巢"), ordered=T), 
 year <- substr(year, 2, 5) 
)

简单的条形图

library(ggplot2)
library(gridExtra)

p1 <- ggplot(emptynest2, aes(x=nesttype, y=proportion)) + geom_bar(aes(fill=year), position="dodge", stat="identity")

p2 <- ggplot(emptynest2, aes(x=nesttype, y=proportion)) + geom_col(aes(fill=year), position="dodge")


grid.arrange(p1, p2, ncol=1)

• geom_col()和geom_bar()的区别在于，geom_col()默认使用原数据，而geom_bar()默认进行count。

12.png

group分组问题

在上图上，ggplot()并没有设置aes()的group参数。这种做法不影响geom_bar()，但是影响geom_text()，使得数据标签不能正确显示。

p3 <- ggplot(emptynest2, aes(x=nesttype, y=proportion)) + 
  geom_col(aes(fill=year), position="dodge") + 
  geom_text(aes(label=proportion, y=proportion+0.05), position=position_dodge(0.9), vjust=0) 

p4 <- ggplot(emptynest2, aes(x=nesttype, y=proportion, group=year)) + 
  geom_col(aes(fill=year), position="dodge") + 
  geom_text(aes(label=proportion, y=proportion+0.05), position=position_dodge(0.9), vjust=0) 

grid.arrange(p3,p4,ncol=1)

13.png

geom_text()的参数设置问题

position问题

对于多组数据，不能直接设置，而要用position_dodge()设置不同组之间标签的避开宽度（dodging width）。

ggplot(emptynest2, aes(x=nesttype, y=proportion, group=year)) + 
  geom_col(aes(fill=year), position="dodge") + 
  geom_text(aes(label=proportion, y=proportion+0.05), position="dodge", vjust=0) 


ggplot(emptynest2, aes(x=nesttype, y=proportion, group=year)) + 
  geom_col(aes(fill=year), position="dodge") + 
  geom_text(aes(label=proportion, y=proportion+0.05), position=position_dodge(0.9), vjust=0) 

21.png 22.png

vjust问题

vjust选项调节数据标签相对于条形顶部的位置。默认为0.5。

ggplot(emptynest2, aes(x=nesttype, y=proportion, group=year)) + 
  geom_col(aes(fill=year), position="dodge") + 
  geom_text(aes(label=proportion, y=proportion+0.05), position=position_dodge(0.9)) 

ggplot(emptynest2, aes(x=nesttype, y=proportion, group=year)) + 
  geom_col(aes(fill=year), position="dodge") + 
  geom_text(aes(label=proportion, y=proportion+0.05), position=position_dodge(0.9), vjust=0) 

ggplot(emptynest2, aes(x=nesttype, y=proportion, group=year)) + 
  geom_col(aes(fill=year), position="dodge") + 
  geom_text(aes(label=proportion, y=proportion+0.05), position=position_dodge(0.9), vjust=1) 

31.png 32.png 33.png

aes()问题

目的是抬升标签的位置，使得标签脱离条形的顶部。默认是贴合。

ggplot(emptynest2, aes(x=nesttype, y=proportion, group=year)) + 
  geom_col(aes(fill=year), position="dodge") + 
  geom_text(aes(label=proportion), position=position_dodge(0.9), vjust=0) 

ggplot(emptynest2, aes(x=nesttype, y=proportion, group=year)) + 
  geom_col(aes(fill=year), position="dodge") + 
  geom_text(aes(label=proportion, y=proportion+1), position=position_dodge(0.9), vjust=0) 

41.png 42.png

---

附录

下面内容节选自geom_text()帮助文件。

# Aligning labels and bars --------------------------------------------------
df <- data.frame(
  x = factor(c(1, 1, 2, 2)),
  y = c(1, 3, 2, 1),
  grp = c("a", "b", "a", "b")
)

# ggplot2 doesn't know you want to give the labels the same virtual width
# as the bars:
ggplot(data = df, aes(x, y, group = grp)) +
  geom_col(aes(fill = grp), position = "dodge") +
  geom_text(aes(label = y), position = "dodge")
# So tell it:
ggplot(data = df, aes(x, y, group = grp)) +
  geom_col(aes(fill = grp), position = "dodge") +
  geom_text(aes(label = y), position = position_dodge(0.9))
# Use you can't nudge and dodge text, so instead adjust the y position
ggplot(data = df, aes(x, y, group = grp)) +
  geom_col(aes(fill = grp), position = "dodge") +
  geom_text(
    aes(label = y, y = y + 0.05),
    position = position_dodge(0.9),
    vjust = 0
  )


# Justification -------------------------------------------------------------
df <- data.frame(
  x = c(1, 1, 2, 2, 1.5),
  y = c(1, 2, 1, 2, 1.5),
  text = c("bottom-left", "bottom-right", "top-left", "top-right", "center")
)
ggplot(df, aes(x, y)) +
  geom_text(aes(label = text))
ggplot(df, aes(x, y)) +
  geom_text(aes(label = text), vjust = "inward", hjust = "inward")

51.png 52.png 53.png 61.png 62.png