我有下面的代码，

set.seed(15)
xdf <- data.frame(
  values = c(
rnorm(n = 20, mean = 0, sd = .4),
rnorm(n = 20, mean = 0.3, sd = .7),
rnorm(n = 20, mean = 0.6, sd = .15),
rnorm(n = 20, mean = 0.2, sd = .4),
rnorm(n = 20, mean = 0.4, sd = .4),
rnorm(n = 20, mean = 0.7, sd = .5)
),
groups = rep(LETTERS[1:6],each=20)
)


library(ggplot2)
library(ggpubr)

ggplot(xdf, aes(x=groups, y=values, fill=groups)) +
geom_boxplot() +
scale_fill_manual(values=pals::brewer.greens(6)) +
theme_pubclean() +
theme(legend.position = 'none') +
xlab("") +
ylab("Values") +  
stat_compare_means(ref.group="A", 
                 method = "t.test", 
                 label.y = maxvals+0.1,
                 symnum.args = list(cutpoints = c(0, 0.0001, 0.001, 0.01, 0.05, 1),  
                 symbols = c("****", "***", "**", "*", "ns"))

生成以下曲线图：

如果我删除了ref.group="A"参数并替换为comparisons=列表，那么synum.args=就可以工作，它会用星号替换p值，而不是T-test, p=0.0016等。然而，当使用参照组时，我似乎不能像我想象的那样用星号替换p值。