如何在ggplot2中并排条形图上居中标签

Posted 2023-02-16

【中文标题】如何在ggplot2中并排条形图上居中标签

【英文标题】：How to center labels over side-by-side bar chart in ggplot2

【发布时间】：2022-01-08 18:27:31

【问题描述】：

我在 ggplot 工作。我创建了一个条形图，但条形图上的标签不在条形图的中心（见图）。

如何在此图中将每个条形的标签居中于其各自的条形上？

代码如下：

df<- structure(list(Cycle = c(1980, 1982, 1984, 1986, 1988, 1990, 
                         1992, 1994, 1996, 1998, 2000, 2002, 2004, 2006, 2008, 2010, 2012, 
                         2014, 2016, 1980, 1982, 1984, 1986, 1988, 1990, 1992, 1994, 1996, 
                         1998, 2000, 2002, 2004, 2006, 2008, 2010, 2012, 2014, 2016), 
               Donor_Location = structure(c(1L, 1L, 1L, 1L, 1L, 1L, 1L, 
                                            1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 2L, 2L, 2L, 
                                            2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 
                                            2L), .Label = c("In District", "Out of District"), class = "factor"), 
               Count_Percentage_Mean = c(0.167598290871218, 0.124829496296588, 
                                         0.0940731004562636, 0.125521769946444, 0.134545184854301, 
                                         0.221904402021545, 0.241031685849158, 0.284978425863672, 
                                         0.280387277343076, 0.269095218446438, 0.273131304975636, 
                                         0.288912758780087, 0.297134465175358, 0.296786491472909, 
                                         0.292365465524159, 0.303877491711499, 0.249983664094922, 
                                         0.258636305966848, 0.239182241578899, 0.159250631842859, 
                                         0.161311478778858, 0.157209833306125, 0.161853462566676, 
                                         0.174277618030726, 0.251786815739142, 0.318324841334214, 
                                         0.312697665544327, 0.347430615609066, 0.346833684171301, 
                                         0.374139881841685, 0.422610276126137, 0.432433986875512, 
                                         0.424992976111316, 0.429557833404775, 0.443001597806887, 
                                         0.462424440669885, 0.45460402775165, 0.492540191333363)), row.names = c(NA, 
                                                                                                                 -38L), class = "data.frame")


ggplot(df, aes(x = Cycle , y = Count_Percentage_Mean, fill = Donor_Location)) +
  geom_bar(stat = "identity", position = 'dodge') +
  scale_y_continuous(labels = scales::percent_format(accuracy = 1)) +
  geom_text(aes(label=paste(round(Count_Percentage_Mean*100,0), "%", sep = "")), position=position_dodge(width=0.9), vjust=-0.5)

谢谢！

【问题讨论】：

查看question 的第二个答案：“position_dodge() 语句采用宽度参数。确保文本在条的末端居中（即，条和文本相同），为 geom_bar 和 geom_text 中的 position_dodge() 语句提供相同的宽度参数。"

【参考方案1】：

尝试为geom_bar 和geom_text 调整position_dodge(width = 2.1)

library(ggplot2)
ggplot(df, aes(x = Cycle , y = Count_Percentage_Mean, fill = Donor_Location)) +
  geom_bar(stat = "identity", position = position_dodge(width = 2.01)) +
  scale_y_continuous(labels = scales::percent_format(accuracy = 1)) +
  geom_text(aes(label = paste(round(Count_Percentage_Mean * 100, 0), "%", sep = "")), 
            position = position_dodge(width = 2.01), vjust = -0.5,
            size = 2)+
  theme(legend.position = "bottom")

^{由reprex package (v2.0.1) 于 2021-12-02 创建}

【讨论】：

太棒了！谢谢您的帮助！这个解决方案也非常有效！

【参考方案2】：

嗯。不幸的是，我不能告诉你这个问题的原因是什么。另外，我不知道 ggplot2 的任何更新或......可能我错过了一些基本的东西（也许我需要再喝一杯咖啡）。反正。我查看了layer_data，您的文本标签仅被条形宽度的一半避开。因此，您可以通过将宽度加倍来达到您想要的结果，即在geom_text 中使用position = position_dodge(width = 1.8)

library(ggplot2)

ggplot(df, aes(x = Cycle, y = Count_Percentage_Mean, fill = Donor_Location)) +
  geom_col(position = "dodge") +
  scale_y_continuous(labels = scales::percent_format(accuracy = 1)) +
  geom_text(aes(label = scales::percent(Count_Percentage_Mean, accuracy = 1)), position = position_dodge(width = 1.8), vjust = -0.5)

【讨论】：

太棒了！谢谢您的帮助！这有效！