How to italicize some words in a sentence in axis text in R

Question

I would like to italicize a part of a term in axis text (not title) in R ggplot2.

I have some bacterial species names that I should write in italic and besides I have the strain name that should be in plain text.

Here is an example of what I have:

My data frame looks like this

MyDF <- data.frame(Activity=rep(c("Activity 1", "Activity 2"), each = 3), 
                   Bacteria = c(sample(c("Escherichia coli Strain 1", "Escherichia coli Strain 2"), 3, TRUE, prob = c(0.3, 0.7)),
                                sample(c("Escherichia coli Strain 1", "Escherichia coli Strain 2"), 3, TRUE, prob = c(0.5, 0.5))))

MyDF
    Activity                  Bacteria
1 Activity 1 Escherichia coli Strain 2
2 Activity 1 Escherichia coli Strain 2
3 Activity 1 Escherichia coli Strain 1
4 Activity 2 Escherichia coli Strain 1
5 Activity 2 Escherichia coli Strain 2
6 Activity 2 Escherichia coli Strain 1

And the code used to generate the plot is:

MyPlot <- ggplot(data = MyDF, mapping = aes(x =Activity , y =Bacteria )) +
  xlab(label = "Activities") +
  ylab(label = "Strains") +
  theme(axis.text.y = element_text(face = "italic", size = 10, family = "serif"))

MyPlot

So my question is how to make "Escherichia coli" in italic and keep "Strain 1" in plain text.

Any help is really appreciated.

Best,

Najoua

score 2 · Accepted Answer · answered Oct 12 '22 at 14:50

2

You could use scale_y_discrete with expression and italic like this:

MyDF <- data.frame(Activity=rep(c("Activity 1", "Activity 2"), each = 3), 
                   Bacteria = c(sample(c("Escherichia coli Strain 1", "Escherichia coli Strain 2"), 3, TRUE, prob = c(0.3, 0.7)),
                                sample(c("Escherichia coli Strain 1", "Escherichia coli Strain 2"), 3, TRUE, prob = c(0.5, 0.5))))

library(ggplot2)
MyPlot <- ggplot(data = MyDF, mapping = aes(x =Activity , y =Bacteria )) +
  xlab(label = "Activities") +
  ylab(label = "Strains") +
  scale_y_discrete('Strains', labels = expression(~italic("Escherichia coli")~'Strain 1', ~italic("Escherichia coli")~'Strain 2'))

MyPlot

^{Created on 2022-10-12 with reprex v2.0.2}

answered Oct 12 '22 at 14:50

Quinten

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thank you for your reply. It worked like magic, but I got another question, please. How can I do the same thing when using facets in ggplot? When doing the same thing, the x text starts over when changing to the next facet. – Najoua Oct 13 '22 at 13:15
@NajouaMghazli, Good question. I would suggest to ask another question. – Quinten Oct 13 '22 at 15:03
I asked a new question in [link]https://stackoverflow.com/questions/74058524/how-to-italicize-some-words-in-a-sentence-in-x-axis-text-in-ggplot-facet but couldn't add the image – Najoua Oct 13 '22 at 15:45

How to italicize some words in a sentence in axis text in R

1 Answers1