为multipanel ggplot添加一个图例

Question

我尝试使用ggplot创建一个包含单个图例的多面板图。我已经能够通过使用以下代码创建我的六个单独的图来创建多面板图：

p1 <- ggplot(data, aes(y = value, x = Time))+     
geom_point(position="dodge")+geom_line(aes(group=group,linetype=group))

我在另外五个图中使用了类似的代码。我在＆＃39;网格中使用了pushViewport函数。库创建一个mutlipanel图：

pushViewport(viewport(layout = grid.layout(2, 3)))  
print(p1,vp = viewport(layout.pos.row = 1, layout.pos.col = 1))     
print(p2,vp = viewport(layout.pos.row = 1, layout.pos.col = 2))
print(p3,vp = viewport(layout.pos.row = 1, layout.pos.col = 3))
print(p4,vp = viewport(layout.pos.row = 2, layout.pos.col = 1))
print(p5,vp = viewport(layout.pos.row = 2, layout.pos.col = 2))
print(p6,vp = viewport(layout.pos.row = 2, layout.pos.col = 3))

我现在想做的但似乎无法弄清楚是为所有六个地块添加一个传奇。我已经阅读了一些关于在绘图边界之外添加图例的内容，但似乎无法将此工具与pushViewport方法一起使用。

Answer 1

以下将使用主题显示左上角的单个图例（legend.justification ='left'，legend.position = c（0,0.75））

library(grid)

数据示例

x<-c(1,1,2,2)
y<-c(107, 110, 110, 118)
data<-data.frame(x,y)
data$group<-as.factor(c(1,2,1,2))

Ggplot

p1 <- ggplot(data, aes(y = y, x = x)) + geom_point(position="dodge") + geom_line(aes(group=group,linetype=group)) + theme(legend.justification = 'left', legend.position=c(0,0.75))
p2 <- ggplot(data, aes(y = y, x = x)) + geom_point(position="dodge") + geom_line(aes(group=group,linetype=group)) + theme(legend.position = "none")
p3 <- ggplot(data, aes(y = y, x = x)) + geom_point(position="dodge") + geom_line(aes(group=group,linetype=group)) + theme(legend.position = "none")
p4 <- ggplot(data, aes(y = y, x = x)) + geom_point(position="dodge") + geom_line(aes(group=group,linetype=group)) + theme(legend.position = "none")
p5 <- ggplot(data, aes(y = y, x = x)) + geom_point(position="dodge") + geom_line(aes(group=group,linetype=group)) + theme(legend.position = "none")
p6 <- ggplot(data, aes(y = y, x = x)) + geom_point(position="dodge") + geom_line(aes(group=group,linetype=group)) + theme(legend.position = "none")

pushViewport(viewport(layout = grid.layout(3, 2)))  
print(p1,vp = viewport(layout.pos.row = 1, layout.pos.col = 1))     
print(p2,vp = viewport(layout.pos.row = 1, layout.pos.col = 2))
print(p3,vp = viewport(layout.pos.row = 2, layout.pos.col = 1))     
print(p4,vp = viewport(layout.pos.row = 2, layout.pos.col = 2))
print(p5,vp = viewport(layout.pos.row = 3, layout.pos.col = 1))     
print(p6,vp = viewport(layout.pos.row = 3, layout.pos.col = 2))