您可以使用fill和..x..在图的固定x值处创建不同的颜色。因此阴影区域在所有图中都是相同的。您可以通过使用ggplot_build和一个单独的 Dataframe 来修改这一点，该 Dataframe 具有作为阈值的p_values。因此，使用这些阈值，您可以有条件地更改图层中的color。下面是一些可复制的代码：

library(ggplot2)
library(tidyverse)
library(ggridges)

df <- data.frame()

set.seed(7) # for reproducibility
for (label in LETTERS) {
  mean=rnorm(1,0.5,0.2)
  null = rnorm(1000,mean,0.1);
  sc = rnorm(1,0.5,0.2)
  df <- rbind(df, data.frame(label=label, null=null, sc=sc))
}

df <- df %>% 
  mutate(label=as.factor(label))
# Create dataframe with p_values ranges per label
p_values = df %>% 
  group_by(label) %>% 
  summarise(p_value = unique(sc)) %>%
  mutate(label = as.integer(label)) # make sure label is the same as in ggplot_build

# plot
p <- ggplot(df, aes(x = null, y = label, fill = ifelse(..x.. < sc, "no sign", "sign"), group = factor(label)))  +
  stat_density_ridges(geom = "density_ridges_gradient",,
                      scale=1.2,alpha = 1, size=1,
                      calc_ecdf = TRUE) +
  scale_fill_manual(values = c("red", "blue"), name = "") +
  coord_flip()
p
#> Picking joint bandwidth of 0.0224

# Modify layer
q <- ggplot_build(p)
#> Picking joint bandwidth of 0.0224
q$data[[1]] = q$data[[1]] %>%
  left_join(., p_values,
            by = c("group" = "label")) %>%
  mutate(fill = case_when(x < p_value ~ fill,
                          TRUE ~ "blue")) %>%
  select(-p_value)
q <- ggplot_gtable(q)
plot(q)

创建于2023-03-28带有reprex v2.0.2
正如你在最新的图中看到的，阴影区域现在是根据每组 Dataframe 的sc值。