如何在ggplot2饼图中保留0值？

Question

我有4个元素：x1 x2 x3 x4和相应的值：

overlap_cha <- data.frame( type=rep(c("x1","x2","x3","x4"),c(18,0,91,3)) )

当我绘制饼图时，图例中不会显示带有0值的x2。

pie <- ggplot(overlap_cha, aes(x = 0, fill = type)) + geom_bar(width = 1)
pie + coord_polar(theta = "y")

我该如何保留它？

Answer 1

这是类似的（但可能不完全相同？）ggplot2 keep unused levels barplot ...

设置数据：

overlap_cha <- data.frame( type=rep(c("x1","x2","x3","x4"),c(18,0,91,3)) )

确保变量具有适当的因子水平：

 overlap_cha$type <- factor(overlap_cha$type,levels=c("x1","x2","x3","x4"))


 library(ggplot2)
 pie <- ggplot(overlap_cha, aes(x = 0, fill = type)) + geom_bar(width = 1)
 pie2 <- pie + scale_fill_discrete(drop=FALSE)+scale_x_discrete(drop=FALSE)+
         coord_polar(theta = "y")

如果您想更改颜色，请使用scale_fill_brewer（或者您可以将scale_fill_manual与values参数一起使用）：

 pie3 <- pie +
     scale_fill_brewer(palette="Set1",drop=FALSE)+
     scale_x_discrete(drop=FALSE)+
         coord_polar(theta = "y")