如何为项目符号图表添加自定义图例

Question

我有以下数据集:

incidents.pct <- data.frame(
  measure=c("Total Events (%)", "Security Events (%)", "Filtered (%)", "Tickets (%)"),
  high=c(100,100,100,100),
  mean=c(45,40,50,30),
  low=c(25,20,10,5), 
  target=c(55,40,45,35),
  value=c(50,45,60,25))

我用它来创建以下"子弹般的"图形.

g <- ggplot(incidents.pct) +
  geom_bar(aes(measure, high),  fill="goldenrod2", stat="identity", width=0.5, alpha=0.2) +
  geom_bar(aes(measure, mean),  fill="goldenrod3", stat="identity", width=0.5, alpha=0.2) +
  geom_bar(aes(measure, low),   fill="goldenrod4", stat="identity", width=0.5, alpha=0.2) +        
  geom_point(aes(measure, target), colour="red", size=2.5) 

这有效,但我希望包含一个解释颜色的自定义图例.所以只是一个带有"低","中等","价值"等的颜色标志......

有关如何包含此内容的任何建议吗？

Answer 1

在ggplot中,如果它在里面,则会自动生成一个美学选项的图例aes().因此,以下解决方法scale_fill_manual()将为您提供一个图例:

ggplot(incidents.pct) +
  geom_col(aes(measure, high, fill = "high"), width=0.5, alpha=0.2) +
  geom_col(aes(measure, mean, fill = "mean"), width=0.5, alpha=0.2) +
  geom_col(aes(measure, low, fill = "low"), width=0.5, alpha=0.2) +        
  geom_point(aes(measure, target), colour="red", size=2.5) +
  scale_fill_manual(name = "Legend",
                    values = c("high" = "goldenrod2", 
                               "mean" = "goldenrod3", 
                               "low" = "goldenrod4"),
                    breaks = c("high", "mean", "low"))

(顺便提一下,geom_col()相当于geom_bar(stat = "identity"),看起来更整洁.

我会警告不要使用重叠条形的低alpha值,因为图例的颜色与图形的颜色不完全匹配.选择三种较浅的色调会更清晰,并将alpha保留为1.