R图例在情节中的位置 [英] R legend placement in a plot

问题描述

我有一个地块，其中的数据可以进入我想用于图例的区域.有没有一种方法可以让图自动在最高数据点上方的标题空间中放入图例以适应图例?

I have a plot that has data that runs into the area I'd like to use for a legend. Is there a way to have the plot automatically put in something like a header space above the highest data points to fit the legend into?

如果我手动输入ylim()参数来扩大尺寸，然后给出我想要图例的位置的确切坐标，我就可以使它工作，但是我希望有一种更灵活的方法来执行此操作因为它是数据库查询的前端，并且数据级别可能具有完全不同的级别.

I can get it to work if I manually enter the ylim() arguments to expand the size and then give the exact coordinates of where I want the legend located, but I'd prefer to have a more flexible means of doing this as it's a front end for a data base query and the data levels could have very different levels.

推荐答案

编辑2017:

使用ggplot和theme(legend.position ="):

use ggplot and theme(legend.position = ""):

library(ggplot2)
library(reshape2)

set.seed(121)
a=sample(1:100,5)
b=sample(1:100,5)
c=sample(1:100,5)

df = data.frame(number = 1:5,a,b,c)
df_long <- melt(df,id.vars = "number")
ggplot(data=df_long,aes(x = number,y=value, colour=variable)) +geom_line() +
theme(legend.position="bottom")

2012年原始答案: 将图例放在底部:

Original answer 2012: Put the legend on the bottom:

set.seed(121)
a=sample(1:100,5)
b=sample(1:100,5)
c=sample(1:100,5)

dev.off()

layout(rbind(1,2), heights=c(7,1))  # put legend on bottom 1/8th of the chart

plot(a,type='l',ylim=c(min(c(a,b,c)),max(c(a,b,c))))
lines(b,lty=2)
lines(c,lty=3,col='blue')

# setup for no margins on the legend
par(mar=c(0, 0, 0, 0))
# c(bottom, left, top, right)
plot.new()
legend('center','groups',c("A","B","C"), lty = c(1,2,3),
       col=c('black','black','blue'),ncol=3,bty ="n")

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