将图例添加到ggarrange图

如何解决将图例添加到ggarrange图

我有两个使用来自两个独立数据集（雄性对雌性）的数据的图，我使用ggarrange()并排布置了这些图。男性用实心圆圈表示，女性用实心圆圈表示。

如何添加图例，以便读者理解哪个图形来自男性数据，哪个图形来自女性数据？

这是我的代码：

Pronotum_Width_Female <- c("6.5","7.4","7.0","6.2","6.3","6.0","6.4","6.9","6.6","6.8","7.2")

Year_Female <- c("1995","1999","2001","2003","2005","2007","2008","2009","2010","2011","2012","2013")

female <- data.frame(Pronotum_Width_Female,Year_Female)

Pronotum_Width_Male <- c("6.4","5.9","5.8","6.5","5.7","6.1","6.5")

Year_Male <- c("1995","2013")

male <- data.frame(Pronotum_Width_Male,Year_Male)

plot1 <- ggplot(female,aes(y=Pronotum_Width_Female,x=Year_Female)) + 
  geom_point(size = 2,shape = 1) + 
  labs(x="Year",y = "Pronotum Width (mm)") + 
  theme(panel.grid.major = element_blank(),panel.grid.minor = element_blank(),panel.background = element_blank(),axis.line = element_line(colour = "black")) +
  theme(axis.title = element_text(size=15),# for axix
        title = element_text(size=15),axis.text = element_text(size=15),axis.title.x = element_text(vjust = 0),axis.title.y = element_text(vjust = 2),legend.title = element_text(vjust = 0.5))+
  coord_cartesian(ylim=c(5,12))


plot2 <- ggplot(male,aes(y=Pronotum_Width_Male,x=Year_Male)) + 
  geom_point(size = 2) + 
  geom_smooth(method = "lm",se = TRUE,col="black",size=1) +
  labs(x="Year",12))

ggarrange(plot2,plot1,labels = c("a)","b)"),ncol = 2,nrow = 1)

解决方法

不确定您要实现的目标，但我认为最简单的方法是将数据绑定在一起，按性别绘制一个图和一个面，这将为面板提供漂亮的标签：

Pronotum_Width_Female <- c("6.5","7.4","7.0","6.2","6.3","6.0","6.4","6.9","6.6","6.8","7.2")
Year_Female <- c("1995","1999","2001","2003","2005","2007","2008","2009","2010","2011","2012","2013")
Female <- data.frame(Pronotum_Width = Pronotum_Width_Female,Year = Year_Female)

Pronotum_Width_Male <- c("6.4","5.9","5.8","6.5","5.7","6.1","6.5")
Year_Male <- c("1995","2013")
Male <- data.frame(Pronotum_Width = Pronotum_Width_Male,Year = Year_Male)

library(ggplot2)
library(dplyr)

d <- dplyr::bind_rows(list(Female = Female,Male = Male),.id = "gender") %>% 
  # Make Pronotum_Width numeric
  mutate(Pronotum_Width = as.numeric(Pronotum_Width))

ggplot(d,aes(y=Pronotum_Width,x = Year)) + 
  geom_point(aes(shape = gender),size = 2) + 
  scale_shape_manual(values = c(Female = 1,Male = 16)) +
  labs(x="Year",y = "Pronotum Width (mm)") + 
  theme(panel.grid.major = element_blank(),panel.grid.minor = element_blank(),panel.background = element_rect(fill = NA),axis.line = element_line(colour = "black")) +
  theme(axis.title = element_text(size=15),# for axix
        title = element_text(size=15),axis.text = element_text(size=15),axis.title.x = element_text(vjust = 0),axis.title.y = element_text(vjust = 2),legend.title = element_text(vjust = 0.5),strip.background.x = element_rect(fill = NA)) +
  coord_cartesian(ylim = c(5,12)) +
  facet_wrap(~gender) +
  # Drop the legend
  guides(shape = FALSE)