vjust inconsistent in stacked bar plot - r

Question

I have a stacked bar plot, with highly unequal heights of bars. I would like to show the percentages on top of each bar.
What I have done so far is the following
df = structure(list(Type = c("Bronchoscopy", "Bronchoscopy", "Endoscopy",
"Endoscopy"), Bacteremia = structure(c(1L, 2L, 1L, 2L), .Label = c("False",
"True"), class = "factor"), count = c(2710L, 64L, 13065L, 103L
), perc = c(97.6928622927181, 2.3071377072819, 99.2178007290401,
0.782199270959903)), class = c("grouped_df", "tbl_df", "tbl",
"data.frame"), row.names = c(NA, -4L), groups = structure(list(
Type = c("Bronchoscopy", "Endoscopy"), .rows = list(1:2,
3:4)), row.names = c(NA, -2L), class = c("tbl_df", "tbl",
"data.frame"), .drop = TRUE))
ggplot(df, aes(x = Type, y = perc, fill = Bacteremia)) +
geom_bar(stat = "identity") +
ylab("percent") +
geom_text(aes(label = paste0(round(perc, 2), "%")), position =
position_stack(vjust = -0.1), color = "black", fontface = "bold")
I can't seem to get the vjust right. It seems like it's not behaving in the same way for the bottom versus the top bar.
What I would like to achieve is to place the percentages slightly higher than the top edge of each bar.
Any ideas?

Answer 1

Here's a possible approach:
ggplot(df, aes(x = Type, y = perc, fill = Bacteremia)) +
geom_bar(stat = "identity") +
ylab("percent") +
geom_text(aes(label = paste0("", round(perc, 2), "%\n"), y = perc),
color = "black", fontface = "bold", nudge_y = 2)
I should elaborate that ggplot2 is going to try to place the geom_text() relative to the data. If you are trying to align horizontally the text labels, you will need to either use annotate() or supply a labelling dataset with type, percent and Bacteremia and call that in geom_text() as below.
labdf <- cbind(df, ypos = c(103, 5, 103, 5))
ggplot(df, aes(x = Type, y = perc, fill = Bacteremia)) +
geom_bar(stat = "identity") +
ylab("percent") +
geom_text(data = labdf,
aes(label = paste0("", round(perc, 2), "%"), y = ypos, x = Type),
color = "black", fontface = "bold")

Answer 2

Here's one way to do it:
df <-
tibble(
Type = c("Bronchoscopy", "Bronchoscopy", "Endoscopy", "Endoscopy"),
Bacteremia = c("False", "True", "False", "True"),
count = c(2710L, 64L, 13065L, 103L)
) %>%
group_by(Type) %>%
mutate(Percent = round((count / sum(count) * 100), 1))
df %>%
ggplot(aes(x = Type, y = Percent, fill = Bacteremia)) +
geom_col() +
geom_label(
data = . %>% filter(Bacteremia == "True"),
aes(y = Percent + 5, label = str_c(Percent, "%")),
show.legend = FALSE
) +
geom_label(
data = . %>% filter(Bacteremia == "False"),
aes(y = 105, label = str_c(Percent, "%")),
show.legend = FALSE
)
The choices of 5 and 105 work on my computer, but may need to be tweaked a bit based on your specific settings and aspect ratio. The first geom_label call sets the y-axis based on the precise percentage, while the second one sets it at a constant level above the bars.
You might also want to play around with using geom_text vs. geom_label to experiment with different color and label settings. The nice thing about geom_label is that it will make it very clear which group is being labeled.