how to assign text to ggplot with a condition when y axis is not numeric in r

Question

I want to annotate a percentage number of missing values for each variable that actually has any missing values somewhere above the corresponding variable blue line. I can add a text using geom_text but I have difficulty with how to select those vars with Nas. I would appreciate any hint with this.

library(ggplot2)
library(naniar)
gg_miss_var(airquality) + labs(y = "Look at all the missing ones")

Answer 1

You can use naniar::miss_var_summary() to create a data frame with labels for all variables with at least one NA:

df <- miss_var_summary(airquality) %>% 
  dplyr::filter(n_miss > 0) %>% 
  dplyr::mutate(pct_label = paste0(round(pct_miss, 1), '%'))

You can then use this data frame inside your geom_text() line:

gg_miss_var(airquality) + 
  geom_text(data = df, aes(x = as.factor(variable), y = n_miss, label = pct_label), 
            vjust = 1.5) +
  labs(y = "Look at all the missing ones")