harry_tukey_help.R

library(agricolae)
library(tidyverse)

mtcars2 <- 
	mtcars %>%
	#move rownames to new column called Model
	rownames_to_column(var = "Model")

# how does cyl predict displacment	
aov_cars <- aov(disp ~ cyl, data = mtcars2)
# tukey_hsd post-hoc test
tukey_hsd <- HSD.test(aov_cars, trt = "cyl")

#get the means and groups tables add the rownames as cylinder
tukey_mean <- rownames_to_column(tukey_hsd$means, var = "cyl")
# same, but select the cylinder and groups only, more explicit for joining
tukey_groups <- rownames_to_column(tukey_hsd$groups, var = "cyl") %>% select(cyl, groups)

#join them together
left_join(tukey_mean, tukey_groups, by = "cyl") %>%
	# make a standard error of the mean column
	mutate(sem = std/r) %>%
	# lets plot now
	ggplot(data = ., aes(x = cyl, y = disp, ymin = disp - sem, ymax = disp + sem, label = groups)) +
		# lets add points for means
		geom_point() +
		# let's have an errorbar for ± sem
		geom_errorbar() +
		# let's now add our groups
		geom_text(colour = "purple", nudge_x = -0.25)