# …start using Sweave, from scratch!

May 1, 2013
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(This article was first published on Tales of R » R, and kindly contributed to R-bloggers)

INTRODUCTION

Sweave is nothing more, nothing less than the best way R can connect with a text editor, in this case LaTeX.

So you don’t know anyting about LaTeX? neither did I 8 months ago… The hyperlinks in this post will take you to some great pages, to learn different things in an organised way. Here’s how I did it (with lots of help from google though!).

It’s important to take it step by step…

Second, you need to install R, from here. Once you have installed it, you will need to install a LaTeX distribution (my preferred LaTeX editor is TeXworks, and I have MiKTeX in MS Windows).

• If you are a MS Windows user, you will find useful this one: MiKTeX
• For Linux users, here can be Kile (from KDE), TeXworks, or other alternatives. First of all you should install LaTeX (e.g. TeX Live), and configure it with these tips.
• For Mac users, you can follow this link which provides instructions to install TeXmaker. You will be able to install TeXworks from here.
• NOTE: Both, MiKTeX and TeXmaker have portable versions, easy to carry in a pendrive!

What TeX editor did you install? If you have TeXworks, the way to configure Sweave is pretty quick and easy (taken from this great link). If you are a beginner, this may be the best option.

CONFIGURING TEXWORKS

If you have TeXworks, all you have to do is go to:

Edit >> Preferences >> Typesetting

Then, you will see this screen:

If you click the “+” button (highlighted in green) to add a new tool, another screen will appear:

You only have to fill in these fields with the name of the new tool, “Sweave” and adding its “arguments” clicking in the “+” sign.

The field “Program” is filled with the path to your R executable, which can be similar to that in the picture. Just be careful to type “slashes” ( / ) instead of “backslashes” ( \ ).

The field “Arguments” will contain all the commands that Sweave needs to connect to the R console, to interpret R’s code and to produce a .TEX file and a .PDF.

In (K)Ubuntu is configured in a similar way:

WRITING A .RNW FILE

Let’s write something in a new Sweave file!. To this, you must create a new text file (e.g. myfirstsweave.txt) , and change its extension to .Rnw -see this for more help-:

myfirstsweave.Rnw

This is a blank file, but you can paste the following code to construct a template:

% This is a Sweave template from TalesofR.wordpress.com.
% When a line is preceeded by a "%" sign, it will be ignored by the program.
% You can write what you want in this way. It usually serves for making invisible comments.
% If you want to make a comment inside the chunk of R code, the symbol to start the line must be "#", instead of "%"
\documentclass{article}
\begin{document}
% chunks of R code are initiated by "<<.... >>=", and ended by "@"
% with <<echo=FALSE>>=, the code is not printed, only the result.
% <<echo=FALSE, message=FALSE, etc...>>= % These are chunk options
You have to enter first the path to your R libraries, often located in your own user.
<<>>=
.libPaths("C:/Users/....../Documents/R/win-library/2.15")
@
The path is set. Let's begin with commands:
<<>>=
# this is a comment inside a chunk, it is not executed as code.
dat <- data.frame(t=seq(0, 2*pi, by=0.1) )
xhrt <- function(t) 16*sin(t)^3
yhrt <- function(t) 13*cos(t)-5*cos(2*t)-2*cos(3*t)-cos(4*t)
dat$y = yhrt(dat$t)
dat$x = xhrt(dat$t)
@

You can write what you want outside the chunks. \\
The next chunk is a plot:
<<label=fig1plot, fig=TRUE>>=
with(dat, plot(x,y, type="l"))
with(dat, polygon(x,y, col="hotpink"))
@

\end{document}

Once you have your template, you must… “compile” it. First, you can highlight the code with nice colours clicking:

Format >> Syntax Coloring >> LaTeX

To compile the LaTeX/Sweave file, you have to click in the pull-down menu, and select:

Sweave

Great! the last step is to click in the green, round “play” button…

Voilà!

EDIT FOR TEXWORKS IN UBUNTU

The installation of TeXworks in my Kubuntu 12.04 has been direct from the console -at least it worked for me-, without following other instructions:

sudo apt-get update
sudo apt-get install texworks


After the configuration of Sweave typesetting -see above-, I was trying to compile my own template, and this error appeared:

Error in texi2dvi(file = file, pdf = TRUE, clean = clean, quiet = quiet, :

Running ‘texi2dvi’ on ‘untitled-1.tex’ failed.

Messages:

Texi2dvi appears to be a script that allows direct compilation of a .pdf from a .Rnw file.

Maybe it’s not the cleanest solution, but I copied the source code of texi2dvi and created a script with it: (sudo gedit if you are running Ubuntu, sudo kate if Kubuntu)

Open up a Terminal and type:

 sudo kate /usr/bin/texi2dvi


Then you can paste the code into this script, and save the changes. To make it executable, type in the Terminal:

 sudo chmod 755 /usr/bin/texi2dvi