plotting p-values using ggplot stat_summary

Question

I want to plot a dataframe (stats) with the coefficient and error bars, and automatically write the p-values above each point.

stats <- data.frame(Coefficient = c(-0.07,-0.04,-0.15173266),
                    p_value = c(.0765210755,0.5176050652,0.0001309025),
                    conf_low = c(-.1544418,-0.1686583,-0.2294873),
                    conf_high = c(0.007812205,0.084939487,-0.073978033),
                    Test = c("TestA","TestB","TestC"))

I am trying to make a function to plot the p-values above each Coefficient point. (The coord_flip in the plot below may also be throwing me off.

give.pval <- function(y){
  return(c(x = Coefficient, label = stats$p_value))
}

The following ggplot is exactly what I need, except for the stat_summary line which I am doing incorrectly

ggplot(stats, aes(x = Test, y = Coefficient)) +
  geom_point(aes(size = 6)) +
  geom_errorbar(aes(ymax = conf_high, ymin = conf_low)) +
  geom_hline(yintercept=0, linetype="dashed") +
  #stat_summary(fun.data = give.pval, geom = "text") + 
  theme_calc() +
  theme(panel.grid.major = element_blank(), panel.grid.minor = element_blank(),
        axis.text.x = element_text(size = 12, vjust = 0.5), axis.title.x = element_text(size = 16),
        axis.text.y = element_text(size = 12), axis.title.y = element_blank(),
        legend.position = "none",
        plot.title = element_text(hjust = 0.5, size = 24)) +
  coord_flip() + 
  ylab("Coefficient")

I would like the have this plot but with the appropriate p-value above each of the three Coefficient points.

Thanks for any advice.

Answer 1

This could be achieved with a geom_text layer where you map p_value on the label aes and some additional nudging

library(ggplot2)

stats <- data.frame(Coefficient = c(-0.07,-0.04,-0.15173266),
                    p_value = c(.0765210755,0.5176050652,0.0001309025),
                    conf_low = c(-.1544418,-0.1686583,-0.2294873),
                    conf_high = c(0.007812205,0.084939487,-0.073978033),
                    Test = c("TestA","TestB","TestC"))

ggplot(stats, aes(x = Test, y = Coefficient)) +
  geom_point(aes(size = 6)) +
  geom_errorbar(aes(ymax = conf_high, ymin = conf_low)) +
  geom_hline(yintercept=0, linetype="dashed") +
  geom_text(aes(label = p_value), nudge_x = .2) +
  theme(panel.grid.major = element_blank(), panel.grid.minor = element_blank(),
        axis.text.x = element_text(size = 12, vjust = 0.5), axis.title.x = element_text(size = 16),
        axis.text.y = element_text(size = 12), axis.title.y = element_blank(),
        legend.position = "none",
        plot.title = element_text(hjust = 0.5, size = 24)) +
  coord_flip() + 
  ylab("Coefficient")