Center all of your ggplot2 titles over the whole plot using a function

add_centered_title.R

library(ggplot2)
library(dplyr)
library(grid)
library(gridExtra)

add_centered_title <- function(p, text, font_size){
  
  title.grob <- textGrob(
    label = text,
    gp = gpar(fontsize = font_size,
             fontfamily = "Arial")
  )
  p1 <- arrangeGrob(p, top = title.grob)
  grid.arrange(p1)
}

# Create chart that needs a centered title
car_count <- ggplot(mtcars %>%
                      mutate(am = ifelse(am == 0, "Manual", "Automatic Transmission")),
                    aes(x = am)) +
  geom_bar() +
  coord_flip()

# Default, not desired behavior:
car_count +
  labs(title = "I want this title to be centered in the page of my report")

# Desired:
add_centered_title(car_count, "I want this title to be centered in the page of my report", 10)