如何在ggplot中添加垂直线的图例? [英] How to add legend for vertical lines in ggplot?
问题描述
我试图用一些垂直线条作为特定时间点的指标来显示线条图,并且有一个图例标记这些时间点。
根据ggplot2第6.4.4节中的示例,我尝试了以下内容:
<$ p (year = 1875:1972,level = Lake Huuron)
vertDf< -data.frame(年= c(1900,1925,1950) ),labels = c(A,B,C))
pltWithLines< -ggplot(huron,aes(x = year,y = level))+
geom_line()+
geom_vline(aes(xintercept = years,color = labels),data = vertDf)+
scale_color_manual(Sample Year,
values = c(A=蓝色,B=红色,C=绿色))
产生一个图表,垂直线的颜色是正确的,但没有传说。
这有什么问题?
您需要 show_guide
ggplot(huron,aes(x = year,y = level))+
geom_line()+
geom_vline(aes(x data = vertDf,show_guide = T)+
scale_color_manual(Sample Year,
values = c(A=blue,B=红色,C=绿色))
I am trying to show a line graph with some vertical lines as indicators of particular time points and have a legend labeling those time points.
Based on the example in section 6.4.4 of the book ggplot2, I've tried the following
huron<-data.frame(year=1875:1972,level=LakeHuron)
vertDf<-data.frame(years=c(1900,1925,1950),labels=c("A","B","C"))
pltWithLines<-ggplot(huron, aes (x=year,y=level)) +
geom_line() +
geom_vline(aes(xintercept=years,color=labels),data=vertDf) +
scale_color_manual("Sample Year",
values=c("A"="blue","B"="red","C"="green"))
This produces a graph with the vertical lines having the correct color, but no legend at all.
What is wrong with this?
you need show_guide
ggplot(huron, aes (x=year,y=level)) +
geom_line() +
geom_vline(aes(xintercept=years, color=labels),data=vertDf, show_guide=T) +
scale_color_manual("Sample Year",
values=c("A"="blue","B"="red","C"="green"))
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