a reproducible gallery of statistical graphics

Mathematical Annotation in R

  • R Core Team ( ) The R Project for Statistical Computing.
  • Lijia Yu ( / GitHub / Twitter) A master candidate majoring in Bioinformatics at Beijing Institute of Genomics.
  • Karl Broman ( / GitHub / Twitter) Department of Biostatistics and Medical Informatics, University of Wisconsin-Madison; research in statistical genetics; developer of R/qtl (for R)
  • Kevin Ushey ( / GitHub / Twitter) MSc., University of British Columbia; interested in statistical genetics and data visualization

Want to write mathematical symbols and expressions in R graphics? You can use an R expression() instead of normal text, e.g. plot(1:10, main = expression(alpha + beta)). Below is a demo that shows you everything about plotting math in R (it was written by the R Core Team; see ?plotmath for details):


plot of chunk plotmath plot of chunk plotmath plot of chunk plotmath plot of chunk plotmath plot of chunk plotmath

Combining expressions and text

If you want to combine multiple mathematical expressions with text, use paste() inside expression(), as in the following.

par(mar = c(4, 4, 2, 0.1))
plot(rnorm(100), rnorm(100),
  xlab = expression(hat(mu)[0]), ylab = expression(alpha^beta),
  main = expression(paste("Plot of ", alpha^beta, " versus ", hat(mu)[0])))

plot of chunk math-text

Finally, if we want to include variables from an R session in mathematical expressions, and substitute in their actual values, we can use substitute().

par(mar = c(4, 4, 2, 0.1))
x_mean <- 1.5
x_sd <- 1.2
hist(rnorm(100, x_mean, x_sd),
  main = substitute(
    paste(X[i], " ~ N(", mu, "=", m, ", ", sigma^2, "=", s2, ")"),
    list(m = x_mean, s2 = x_sd^2)

plot of chunk math-text-sub


Keywords: Categories: Reviewer: You can find the R Markdown source document in the vistat repository on GitHub.