Introduction

When ggplot is making box plots or dot plots, it can actually check and add p-values, just use the functions of the ggpubr package

Code exmaple

library(ggplot2)
library(ggpubr)

Do t test for groups A, B, C, and D respectively, set in the comparisons parameter,the inspection method is set in the method, can be t.test, t.test, t.test, wilcox.test, wilcox.test, wilcox.test, anova, anova, kruskal.test, kruskal.test

ggplot(InsectSprays, aes(x = spray, y= count,fill = spray)) + geom_boxplot() + theme_classic()+
  geom_point(position = "jitter") +
  stat_compare_means(method = "t.test", 
                     comparisons = list(c("A", "B"),c("C","D")),
                     label.y = c(25, 14)
                     )

Select only groups A and B, use label.x.npc = .5, set the label in the middle

dp <- InsectSprays[InsectSprays$spray %in% c("A", "B"),]
dp$spray <- as.factor(dp$spray)
ggplot(dp, aes(x = spray, y= count,fill = spray)) + geom_boxplot() + theme_classic()+
  geom_point(position = "jitter") +
  stat_compare_means(label.x.npc = .5)