Usage
library(latex2exp)The latex2exp function takes a LaTeX string and returns a plotmath expression suitable for use in plotting, e.g.,
latex2exp('$\\alpha^\\beta$')(note it is always necessary to escape the backslash, hence the double backslash).
The return value of latex2exp can be used anywhere a plotmath expression is accepted, including plot labels, legends, and text.
The following example shows plotting in base graphics:
x <- seq(0, 4, length.out=100)
alpha <- 1:5
plot(x, xlim=c(0, 4), ylim=c(0, 10), xlab='x', type='n',
ylab=latex2exp('$\\alpha x^\\alpha$, where $\\alpha \\in 1\\ldots 5$'),
main=latex2exp('Using $\\LaTeX$ for plotting in base graphics!'))
invisible(sapply(alpha, function(a) lines(x, a*x^a, col=a)))
legend('topleft', legend=latex2exp(sprintf("$\\alpha = %d$", alpha)), lwd=1, col=alpha)
This example shows plotting in ggplot2:
library(plyr)
library(ggplot2)
x <- seq(0, 4, length.out=100)
alpha <- 1:5
data <- mdply(alpha, function(a, x) data.frame(v=a*x^a, x=x), x)
p <- ggplot(data, aes(x=x, y=v, color=X1)) +
geom_line() +
ylab(latex2exp('$\\alpha x^\\alpha$, where $\\alpha \\in 1\\ldots 5$')) +
ggtitle(latex2exp('Using $\\LaTeX$ for plotting in ggplot2. I $\\heartsuit$ ggplot!')) +
coord_cartesian(ylim=c(-1, 10)) +
guides(color=guide_legend(title=NULL)) +
scale_color_discrete(labels=lapply(sprintf('$\\alpha = %d$', alpha), latex2exp))
# Note that ggplot2 legend labels must be lists of expressions, not vectors of expressions
print(p)
You can quickly test out what a translated LaTeX string would look like by using plot:
plot(latex2exp("A $\\LaTeX$ formula: $\\frac{2hc^2}{\\lambda^5} \\,
\\frac{1}{e^{\\frac{hc}{\\lambda k_B T}} - 1}$"), cex=2)
