Legend label combined plots (ggplot and patchwork)

Question

I am new to R and trying to find a simple way to change the labels of the legend for combined boxplots created with ggplot and patchwork.

I am comparing the proportions of 5 different types of cells in 2 groups (controls and asthmatic). I created boxplot for each cell type, and combined them with patchwork.

plot_mac <-  ggplot(asthma_desc, aes(x=control_case, y=BAL_mac_LP, color=control_case)) + 
  geom_boxplot(width=0.5,lwd=0.5) +
  geom_jitter(width=0.15) +
  labs(y = "Macrophages %") +
  stat_compare_means(label = "p.signif", label.x.npc = "center", label.y = 80, hide.ns = T)

then I do the same for 4 different types of cells.

patchwork <- plot_mac + plot_lym + plot_neu + plot_mast + plot_eos + plot_layout(guides = 'collect') 

patchwork & theme_minimal() & scale_color_manual(values=c("black", "red")) & 
  theme(axis.title.x = element_blank(), axis.ticks.x=element_blank(), axis.text.x=element_blank(), text=element_text(size=7)) & 
  ylim(0,100)

I get the following plot

I would like to change the legend "control_case" to "Group", "1" to "control, "2" to "case". I could not make it work with labs(), scale_x_discrete() nor with theme().

Answer 1

Another option is to add a new column to your dataframe named Group. Here is an example with mock mtcars dataset:

library(tidyverse)
library(ggpubr)
library(patchwork)

mtcars1 <- mtcars %>% 
    mutate(Group = case_when( am==0 ~"control", 
                                       am==1~"case",
                                       TRUE ~ NA_character_))
    


p1 <- ggplot(mtcars1, aes(x=Group, y=mpg, color=Group)) + 
    geom_boxplot(width=0.5,lwd=0.5) +
    geom_jitter(width=0.15) +
    labs(y = "Macrophages %") +
    stat_compare_means(label = "p.signif", label.x.npc = "center", label.y = 80, hide.ns = T)

p2 <- ggplot(mtcars1, aes(x=Group, y=wt, color=Group)) + 
    geom_boxplot(width=0.5,lwd=0.5) +
    geom_jitter(width=0.15) +
    labs(y = "Macrophages %") +
    stat_compare_means(label = "p.signif", label.x.npc = "center", label.y = 80, hide.ns = T)

p3 <- ggplot(mtcars1, aes(x=Group, y=hp, color=Group)) + 
    geom_boxplot(width=0.5,lwd=0.5) +
    geom_jitter(width=0.15) +
    labs(y = "Macrophages %") +
    stat_compare_means(label = "p.signif", label.x.npc = "center", label.y = 80, hide.ns = T)

patchwork <- p1 + p2 + p3 + plot_layout(guides = 'collect') 


patchwork & theme_minimal() & scale_color_manual(values=c("black", "red")) & 
    theme(axis.title.x = element_blank(), axis.ticks.x=element_blank(), axis.text.x=element_blank(), text=element_text(size=7)) & 
    ylim(0,100)