Moving geom_text labels to be directly on top of error bars in ggplot2

Question

I am in a new field where they put letters directly on top of error bars to denote significance. I am able to put labels on top of my error bars, but they are uniformly spaced away from the bars, leaving some with small errors very far away from the bars and looking very strange. Is there a way to put the letter right on top of the error bar? In other words, can I adjust each individual label for each bar?

example pic

Here is my code:

my_lab<-c("A","B","BC","C","C","BC")

ggplot(g, aes(x=factor(rate, level=c('0','0.1','1.8','7.3','10.3','15.3')), y=number, fill=species)) +
  geom_bar(stat='identity', color="black", width = 0.5)+
  geom_errorbar(aes(ymax=number+se, ymin=number), width=0.2)+
  labs(y=my_y_title, x=expression("Ethanol release rate (g/day)"))+
  geom_text(data=g, aes(label=my_lab), size=8, vjust=-23)+
  theme(panel.grid.major = ele[enter image description here][1]ment_blank(), 
        panel.grid.minor = element_blank(),panel.background = element_blank(), 
        axis.line = element_line(colour = "black"))+
  theme(text = element_text(size=20))+
  theme(axis.text.x = element_text(vjust = 0.95, hjust=1))+
  theme(axis.text.y = element_text(hjust=1))+
  theme(legend.position = "none")+
  scale_fill_manual(values=c('#104E8BC8'))+
  theme(plot.title = element_text(vjust = -12, hjust = 0.7))+
  theme(plot.subtitle = element_text(vjust = -12, hjust = 0.7))+
  theme(plot.margin = margin(t = 0,  # Top margin
                             r = 0,  # Right margin
                             b = 0,  # Bottom margin
                             l = 0))```

For a better explanation make a [minimal reproducible example (MRE)](https://stackoverflow.com/a/5963610/11570343) of your data using `dput` — cdcarrion, Oct 11 '22 at 15:40

score 0 · Accepted Answer · answered Oct 11 '22 at 16:24

You can just define aes(y = number + se, ...) in the text layer to place the text at the top position of the bar.

You can set vjust = 0 to have the text touch the errorbar, or make it smaller (e.g. vjust = -0.5) to move it slightly away from the top of the bar. Note that the vjust is in units of text height, so vjust = -0.5 moves the text half a text height above the anchor point.

Alternatively, you can use the nudge_y argument to move the text by units defined by the data.

Dummy example with build-in dataset below:

library(dplyr)
library(ggplot2)

df <- iris |>
  group_by(Species) |>
  summarise(number = mean(Sepal.Width), se = sd(Sepal.Width) / sqrt(n())) |>
  mutate(label = c("A","BC", "DEF"))

ggplot(df, aes(Species, number)) +
  geom_col() +
  geom_errorbar(
    aes(ymin = number, ymax = number + se), 
    width = 0.2
  ) +
  geom_text(
    aes(y = number + se, label = label), 
    vjust = 0, nudge_y = 0
  )

^{Created on 2022-10-11 by the reprex package (v2.0.1)}

`geom_text(aes(y = number + se` solved it for me. Thanks so much! — user20214781, Oct 11 '22 at 19:05

Moving geom_text labels to be directly on top of error bars in ggplot2

1 Answers1