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LaTex in R Graphs

· Big Data Zone

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A nice post was recently published on the rsnippets blog, about the tikzDevice R package. This package is – indeed – awesome. Even if it has been removed from the CRAN website. Of course, it can be download from the archive folder, on http://cran.r-project.org/…, but also (for a more recent version)  on http://download.r-forge.r-project.org/…. But first, it is necessary to install the following package.

> install.packages("filehash")

Then, we download on of the tikzDevice.zip files, and load it, e.g. using (on Mac)

Then, we can load the library

> library("tikzDevice")

If we want to use nice LaTeX formulas, it might be necessary to upload some (LaTeX) libraries and to specify the encoding format

> "options(tikzMetricPackages = c("\\usepackage[utf8]{inputenc}",
+ "\\usepackage[T1]{fontenc}", "\\usetikzlibrary{calc}", "\\usepackage{amssymb}"))

(this is detailed, e.g. in http://yihui.name/…), then, we write a code to plot a graph. The idea is to produce a tex file which contains the graph, or more precisely which will produce a pdf graph when we compile it. We start with

> tikz("normal-dist.tex", width = 8, height = 4, 
+ standAlone = TRUE,
+ packages = c("\\usepackage{tikz}",
+ "\\usepackage{preview}",
+ "\\PreviewEnvironment{pgfpicture}",
+ "\\setlength\\PreviewBorder{0pt}",
+ "\\usepackage{amssymb}"))

We will produce a 8×4 graph. The graph is the following,

> u=seq(-3,3,by=.01)
> plot(u,dnorm(u),type="l",axes=FALSE,xlab="",ylab="",col="white")
> axis(1)
> I=which((u>=0)&(u<=1))
> polygon(c(u[I],rev(u[I])),c(dnorm(u)[I],rep(0,length(I))),col="red",border=NA)
> lines(u,dnorm(u),lwd=2,col="blue")

We can add text (or TeX based text)

> text(-1.5, dnorm(-1.5)+.17, "$\\textcolor{blue}{X\\sim\\mathcal{N}(0,1)}$", cex = 1.5)
> text(1.75, dnorm(1.75)+.25, 
+ "$\\textcolor{red}{\\mathbb{P}(X\\in[0,1])=\\displaystyle{\\int_0^1 \\varphi(x)dx}}$", cex = 1.5)

And we end the file with a standard

> dev.off()

This will produce a [a href="http://freakonometrics.free.fr/normal-dist.tex" style="text-decoration: none; outline-style: none; color: rgb(0, 130, 137);"].tex file. If we compile this file, we can generate a pdf file, that can be inserted in lecture notes, slides or articles,

Nice, isn’t it ?

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Published at DZone with permission of Arthur Charpentier, DZone MVB. See the original article here.

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