R Programming/Publication quality ouput

< R Programming

Formatting numbers

You can use the format() function to control the number of digits and other characteristics of a displayed object. 

> df <- data.frame(x = rnorm(10), y = rnorm(10))
> print(df)
            x          y
1  -0.4350953 -0.6426477
2  -0.5947293 -0.2389625
3  -0.7061850 -2.4382016
4  -0.3384038 -0.6322842
5   0.2713353  0.5396409
6  -1.1144711 -2.0321274
7  -1.0356184  1.7217443
8  -2.6665278 -0.3621377
9   0.2975570  0.1598905
10  1.4631458 -0.7995652
> print(format(df, digits=3, scientific=T))
           x         y
1  -4.35e-01 -6.43e-01
2  -5.95e-01 -2.39e-01
3  -7.06e-01 -2.44e+00
4  -3.38e-01 -6.32e-01
5   2.71e-01  5.40e-01
6  -1.11e+00 -2.03e+00
7  -1.04e+00  1.72e+00
8  -2.67e+00 -3.62e-01
9   2.98e-01  1.60e-01
10  1.46e+00 -8.00e-01

Sweave

Sweave[1] is a literate programming language which integrates LaTeX and R code. The Sweave file generates a LaTeX file and an R file which can in turn be compiled. Roger Koenker[2], Meredith and Racine (2009)[3] and Charles Geyer[4] argue that Sweave favors reproducible econometric/statistical research.

There are some alternatives to Sweave for literate programming. One of them is Babel which is included in Emacs Orgmode[5]. This tool allow export to LaTeX and HTML. It is also possible to include code chunks for various programming languages (R, Ruby, etc).

Syntax

The main idea is that you write a file which includes LaTeX and R code. LaTeX code begins with @ and R code with <<>>= (some options can be included between << and >>). 

@
% Some LaTeX code
\section{Results}
I show that ...
<<>>=
# Some R code
qnorm(.975)
@
% Some LaTeX code
$$
\Phi^{-1}(.975) = 1.96 
$$

The file is stored with extension .Rnw or .rnw. At the end, you extract from this file an R file using Stangle() and a LaTeX file using Sweave(). Here is an example with a file called file.Rnw which generates file.tex and file.R

> Sweave("file.Rnw")
Writing to file file.tex
Processing code chunks ...
 1 : echo keep.source term verbatim pdf
 2 : echo keep.source term verbatim pdf
> Stangle("file.Rnw")
Writing to file file.R

Then you can run LaTeX on your file.tex. This can be done using the system() function or texi2dvi(). 

# Example under Windows :
system("pdflatex.exe -shell-escape file.tex") # runs pdflatex
system("open file.pdf") # opens the pdf

Note that you may need to download Sweave.sty from the internet since it is not part of the standard MikTeX distribution.

You can also add your results in your text using the \Sexpr{} function. 

$
\Phi^{-1}(.975) = \Sexpr{qnorm(.975)} 
$

Options

There are some options. These options can be included for each code chunk or in the Sweave command.

By default, figures are exported as pdf and eps files. If you only want one format suppress the other one with pdf=F or eps=F option.

These options can be passed to the Sweave() function. 

Sweave("file.Rnw", pdf = T, eps=F, echo = F, results = "verbatim")

They can also be passed to each code chunk. 

<<fig=T,pdf=T,eps=F>>=
plot(rnorm(100), col = "red")
@

Text editor for Sweave

The main issue with Sweave is that few text editors include syntax highlighting for Sweave. Here are some exceptions :

See also

Some example of Sweave documents :

Some handouts :

Some packages

Some alternative literate programming packages :

Pubprint

Pubprint is a small utility that is able to transform the output of statistical tests to publication ready output. Pubprint is able to export outputs to severall formats (HTML, LaTeX, Markdown and plain text), but unfortunately supports only the APA style (publication style of the American Psychological Association). However, this style is widely used and may be appropriate in more cases.

Example 

> library("pubprint")
> pprint(t.test(rnorm(30), rnorm(30)))
[1] "(\\ensuremath{M\\ifmmode_{x}\\else\\textsubscript{x}\\fi=-0.05,M\\ifmmode_{y}\\else\\textsubscript{y}\\fi=0.09,t[57.74]=-0.49,p=.628})"

Obviously pubprint prints a LaTeX formatted string, but changing the output format is possible (according to the manual pubprint is intended to use with knitr and detects output format automatically if it is used with it):

> pp_opts_out$set(pp_init_out("plain"))
> pprint(t.test(rnorm(30), rnorm(30)))
[1] "(M_x=-0.14,M_y=-0.24,t[57.4]=0.41,p=.682)"
> pprint(cor.test(rnorm(30), rnorm(30)))
[1] "(r=-.08,p=.693)"

The output can be pasted into a documented or may included in a knitr/sweave \Sexpr{} statement.

Export to LaTeX

R has lots of functions which allow it to export results to LaTeX[9].

General functions

toLatex() in the utils package. 

> toLatex(sessionInfo())
\begin{itemize}
  \item R version 2.2.0, 2005-10-06, \verb|powerpc-apple-darwin7.9.0|
  \item Base packages: base, datasets, grDevices,
    graphics, methods, stats, utils
\end{itemize}

> tex.table(mydat)
\begin{table}[ht]
\begin{center}
\begin{footnotesize}
\begin{tabular}{r|rrr}
\hline
 & y & x1 & x2\\ \hline
1 & -0.09 & -0.37 & -1.04\\ 
2 & 0.31 & 0.19 & -0.09\\ 
3 & 3.78 & 0.58 & 0.62\\ 
4 & 2.09 & 1.40 & -0.95\\ 
5 & -0.18 & -0.73 & -0.54\\ 
6 & 3.16 & 1.30 & 0.58\\ 
7 & 2.78 & 0.34 & 0.77\\ 
8 & 2.59 & 1.04 & 0.46\\ 
9 & -1.96 & 0.92 & -0.89\\ 
10 & 0.91 & 0.72 & -1.1\\ 
\hline
\end{tabular}
\end{footnotesize}
\end{center}
\end{table}



> # lm example
> library(xtable)
> x <- rnorm(100)
> y <- 2*x + rnorm(100)
> lin <- lm(y~x)
> xtable(lin)
% latex table generated in R 2.15.1 by xtable 1.7-0 package
% Sun Sep 23 21:54:04 2012
\begin{table}[ht]
\begin{center}
\begin{tabular}{rrrrr}
  \hline
 & Estimate & Std. Error & t value & Pr($>$$|$t$|$) \\ 
  \hline
(Intercept) & -0.0407 & 0.0984 & -0.41 & 0.6803 \\ 
  x & 2.0466 & 0.1043 & 19.63 & 0.0000 \\ 
   \hline
\end{tabular}
\end{center}
\end{table}

> # table example
> x <- sample(1:10, 30, replace = T)
> tab <- table(x)
> tab <- cbind(tab, prop.table(tab))
> colnames(tab) <- c("N.", "Prop.")
> xtable(tab, digits = c(0, 0, 2))
% latex table generated in R 2.15.1 by xtable 1.7-0 package
% Sun Sep 23 22:06:36 2012
\begin{table}[ht]
\begin{center}
\begin{tabular}{rrr}
  \hline
 & N. & Prop. \\ 
  \hline
1 & 5 & 0.17 \\ 
  3 & 1 & 0.03 \\ 
  4 & 3 & 0.10 \\ 
  5 & 6 & 0.20 \\ 
  6 & 5 & 0.17 \\ 
  7 & 3 & 0.10 \\ 
  8 & 2 & 0.07 \\ 
  9 & 2 & 0.07 \\ 
  10 & 3 & 0.10 \\ 
   \hline
\end{tabular}
\end{center}
\end{table}

See also :

Descriptive statistics

Estimation results 

N <- 10^3
u <- rnorm(N)
x1 <- rnorm(N)
x2 <- x1 + rnorm(N)
y <- 1 + x1 + x2 + u
lm1 <- lm(y ~ x1 + x2 )
lm2 <- lm(y ~ x1 + x2 + I(x1*x2))

library(estout)
estclear() # clear all the eststo objects
eststo(lm1) 
eststo(lm2)
esttab() # print it

library("apsrtable")
apsrtable(lm1,lm2)

library(xtable)
xtable(lm1)
tab <- xtable(lm1)
print(tab,type="html")

source("http://pj.freefaculty.org/R/WorkingExamples/outreg-worked.R")
outreg(list(lm1,lm2))

library("memisc")
toLatex(mtable(lm1,lm2))

Export to HTML

The rpublisher[17] is a literate programming language which publish results in HTML (it is based on python and was last updated in 2008).


See R2HTML, xtable, hwriter, prettyR, highlight, HTMLUtils


wiki.table() in the hacks package export a matrix or a dataframe into Mediawiki table markup (as used on this wiki and many others).

> wiki.table(matrix(1:16,4),caption="Test")
{|  
|+ Test 
| 1 || 5 || 9 || 13 
|-
| 2 || 6 || 10 || 14 
|-
| 3 || 7 || 11 || 15 
|-
| 4 || 8 || 12 || 16 
|}

References

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