Superscript in axis labels in ggplot2 for ions

Question

I need to achieve superscript in an axis label within ggplot2, similiar to this question: Superscript and subscript axis labels in ggplot2

However, I will need to write something like this: Ca^2+. This seems not to work with this approach, even if I put the exponent in { } with the bquote command. I tried to read through help("plotmath") but couldn't find an example for my case. I tried escaping the + with \+ and ++ but was not successful.

Edit: I would like to not use any additional packages.

score 3 · Answer 1 · answered Jul 21 '20 at 08:57

3

Using the example you provided, this works

library(ggplot2)
qplot(uptake, data = CO2) +
  xlab(bquote('Assimilation ('*mu~ 'mol' ~Ca^{"2+"} ~ m^-2~s^-1*')'))

answered Jul 21 '20 at 08:57

matushiq

66
4

Shoot! I did not think of using quotation marks, thanks @matushiq. – stephanmg Jul 21 '20 at 09:14

score 2 · Answer 2 · answered Jul 21 '20 at 08:49

using the ggtext package makes this straight forward. Code shamelessly adapted from Claus Wilke's example in the readme. https://github.com/wilkelab/ggtext

library(tidyverse)
library(ggtext)
library(glue)

data <- tibble(
  atom = "Ca",
  charge = "2+",
  value = -0.5
)

data %>% mutate(
  color = "#009E73",
  name = glue("<i style='color:{color}'>{atom}</i><b><sup>{charge}</sup></b>"),
  name = fct_reorder(name, value)
)  %>%
  ggplot(aes(value, name, fill = color)) + 
  geom_col(alpha = 0.5) + 
  scale_fill_identity() +
  labs(caption = "Example shamelessly adapted from Claus Wilke") +
theme(
    axis.text.y = element_markdown(),
    plot.caption = element_markdown(lineheight = 1.2)
  )

^{Created on 2020-07-21 by the reprex package (v0.3.0)}

I may even have overcomplicated it - I added the tag because I thought the OP wanted to have the superscript bold too. — tjebo, Jul 21 '20 at 08:54

score 2 · Accepted Answer · answered Jul 21 '20 at 08:54

2

Try to put the superscript as a literal, between quotes.

g <- ggplot(iris, aes(Species, Sepal.Length)) + geom_boxplot()
g + xlab(bquote('Superscript as a literal' ~~ Ca^'2+'))

answered Jul 21 '20 at 08:54

Rui Barradas

70,273
8
34
66

1

@stephanmg I guess so, yes. That depends on the amount of space you want between the text and the symbol. – Rui Barradas Jul 21 '20 at 09:42
1

I think I can accept this answer, I'm sorry I cannot accept multiple answers. – stephanmg Jul 21 '20 at 09:43

Superscript in axis labels in ggplot2 for ions

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