如何更改geom_text（）在绘图区域外的字体大小？

Question

我想注释一个情节，我想让笔记在情节区外。我发现this solution它适用于在绘图区域外添加笔记，但我无法弄清楚如何更改标签的外观（最重要的是，为了我的目的，字体大小）。

下面是从上述方案中一个最小的例子：

library (ggplot2) 
library(grid) 

df=data.frame(y=c("dog1","dog2","dog3"),x=c(12,10,14),n=c(5,15,20)) 
p <- ggplot(df, aes(x,y)) + geom_point() 

# Add the annotation 
p <- p + geom_text(aes(label = "Hello World!", x = 0, y = 0), vjust = 2, hjust = 1) 

# Code to override clipping 
gt <- ggplot_gtable(ggplot_build(p)) 
gt$layout$clip[gt$layout$name == "panel"] <- "off" 
grid.draw(gt) 

理想的情况下，说明将在左下角。

Answer 1

library (ggplot2) 
library(grid) 

df=data.frame(y=c("dog1","dog2","dog3"),x=c(12,10,14),n=c(5,15,20)) 
p <- ggplot(df, aes(x,y)) + geom_point() 

# Add the annotation 
p <- p + geom_text(size=8, colour="red", aes(label = "Hello World!", x = 0, y = 0), vjust = 2.5, hjust = 1) 

# Code to override clipping 
gt <- ggplot_gtable(ggplot_build(p)) 
gt$layout$clip[gt$layout$name == "panel"] <- "off" 
grid.draw(gt)