Add line break to axis labels and ticks in ggplot

Question

I'm looking for a way to use long variable names on the x axis of a plot. Of course I could use a smaller font or rotate them a little but I would like keep them vertical and readable.

As an example:

df <- data.frame(a=LETTERS[1:20], b=rnorm(20), c=rnorm(20), d=rnorm(20)) df_M <- melt(df, id="a") plot <- ggplot(data=df_M,                 aes(x=variable, y=a, fill=value)) +            geom_tile() +            scale_fill_gradient(low="green", high="red") plot 

here the x axis is just letters, but if I want to use the full name, the names use a disproportionate amount of space:

    plot +         theme(axis.text.x=element_text(angle=90)) +        scale_x_discrete(breaks=unique(df_M$variable),                         labels=c("Ambystoma mexicanum",                                  "Daubentonia madagascariensis",                                 "Psychrolutes marcidus")) 

So I would like to put a line break in the labels. Preferably in ggplot2 but other solutions are welcome of course.

Thanks!

Answer 1

You can add your own formatter ( see scales package for more examples). Here I replace any space in your x labels by a new line.

addline_format <- function(x,...){     gsub('\\s','\n',x) }  myplot +      scale_x_discrete(breaks=unique(df_M$variable),      labels=addline_format(c("Ambystoma mexicanum",                          "Daubentonia madagascariensis", "Psychrolutes marcidus")))