Search code examples
rggplot2

Add only one figure label for multiple subfigures

I have a figure that contains 4 subfigures and want to add only one figure label on the left top corner, say (A). How can I add that line in my code below?

data("iris")

iris1 <- iris2 <- iris3 <- iris

fig <- list()

fig[[1]] <- ggplot(data=iris,mapping=aes(x=Petal.Length,y=Petal.Width,color=Species))+
  geom_point()+
  geom_smooth(method="lm") +
  labs(title = paste0("the title is ", expression(m[0])))

fig[[2]] <- ggplot(data=iris1,mapping=aes(x=Petal.Length,y=Petal.Width,color=Species))+
  geom_point()+
  geom_smooth(method="lm") +
  labs(title = paste0("the title is ", expression(m[1])))

fig[[3]] <- ggplot(data=iris2,mapping=aes(x=Petal.Length,y=Petal.Width,color=Species))+
  geom_point()+
  geom_smooth(method="lm") +
  labs(title = paste0("the title is ", expression(m[2])))

fig[[4]] <- ggplot(data=iris3,mapping=aes(x=Petal.Length,y=Petal.Width,color=Species))+
  geom_point()+
  geom_smooth(method="lm") +
  labs(title = paste0("the title is ", expression(m[3])))

 fig_all <- ggpubr::ggarrange(plotlist = fig, ncol = 2, nrow = 2, common.legend = TRUE, legend = "top")

 fig_all

The generated figure is as follows, but there is no figure label. I don't want to have label for each subfigures, but instead just one label to indicate for all, on the top left corner.

enter image description here

Solution

  • You can use ggpubr::annotate_figure

    library("ggplot2")
library("ggpubr")
data("iris")

fig <- list()

fig[[1]] <- ggplot(data=iris,mapping=aes(x=Petal.Length,y=Petal.Width,color=Species))+
  geom_point()+
  geom_smooth(method="lm")

fig[[2]] <- ggplot(data=iris,mapping=aes(x=Petal.Length,y=Petal.Width,color=Species))+
  geom_point()+
  geom_smooth(method="lm")

fig[[3]] <- ggplot(data=iris,mapping=aes(x=Petal.Length,y=Petal.Width,color=Species))+
  geom_point()+
  geom_smooth(method="lm")

fig[[4]] <- ggplot(data=iris,mapping=aes(x=Petal.Length,y=Petal.Width,color=Species))+
  geom_point()+
  geom_smooth(method="lm")

fig_all <- ggpubr::ggarrange(plotlist = fig, ncol = 2, nrow = 2, common.legend = TRUE, legend = "top")

ggpubr::annotate_figure(fig_all, 
                        fig.lab = 'Main Title',
                        fig.lab.pos = 'top.left',
                        fig.lab.size = 16, 
                        fig.lab.face = 'bold')