动态引用Sweave文档中R注释中的图形 [英] Dynamic references to figures in a R comment within Sweave document

问题描述

我想找到一种方法来使用LaTeX \ref{}标记在Sweave .Rnw文件中的R代码中添加注释.这是两个示例，一个在印刷中

I would like to find a way to use the LaTeX \ref{} markup to comment in the R code within a Sweave .Rnw file. Here are two examples, one in print

http://cm.bell- labs.com/cm/ms/departments/sia/project/nlme/UGuide.pdf

和可用于工作的一个:

.Rnw文件

% File: example.Rnw

\documentclass{article}
\usepackage{fullpage}
\usepackage{graphics}
\usepackage{Sweave} 
\usepackage[margin = 10pt, font=small, labelfont={bf}]{caption}

\begin{document}

Here is an example file to show what I want to do.  I would like to figure out how to use the \LaTeX\ reference command to reference a figure being generated by R code.  Note in the R code, in a comment there is a reference to the figure, but of course the output file shows a verbatim copy of the \LaTeX\ markup.  Does anyone know how to get something for Figure \ref{fig2}?

<< example plot >>=
library(reshape)
library(ggplot2)

n <- 100
lambda <- 1 / 3 
x <- seq(0, qexp(0.999, rate = lambda), length = n)
q1.a <- data.frame(x =   x,
                   f =   dexp(x, rate = lambda),
                   F =   pexp(x, rate = lambda))

q1.a <- melt(q1.a, id.vars = 'x')
g <- ggplot(q1.a) +                                     # Produces \ref{fig1} 
       aes(x = x, y = value) + 
       geom_line() + 
       facet_wrap( ~ variable, scale = "free_y")
ggsave(g, filename = "example1.jpeg")                    
@

\begin{figure}[h]
\centering
\includegraphics[width = 0.48\textwidth]{./example1}
\caption{Exponential Distribution based plots.}
\label{fig1}
\end{figure}

Here is more of what I would like to see:

<< example plot 2 >>=
ggsave(g + geom_point(), filename = "example2.jpeg")    # Produces Figure 2
@

\begin{figure}
\centering
\includegraphics[width = 0.48\textwidth]{./example2}
\caption{Exponential Distribution based plots with points and lines.}
\label{fig2}
\end{figure}

\end{document}

并且pdf是使用R命令构建的

and the pdf is build with the R commands

Sweave(file = 'example.Rnw',
       engine = "R",
       keep.source = 'TRUE',
       echo = 'TRUE',
       results = 'verbatim')

tools::texi2dvi(file  = "example.tex",
                pdf   = TRUE,
                clean = TRUE)

任何有关如何做到这一点的见识都很好.

Any insight on how do this would be great.

推荐答案

这是通过重新定义Sinput环境(其中源代码由Sweave包装)来解决此问题的一种方法.默认情况下，这是一个简单的verbatim环境，latex不会处理令牌.技巧是重新定义它以使用alltt环境，该环境允许在alltt环境中解析某些标记.请注意，这可能会导致我不知道的不良副作用，因此请谨慎使用！

Here is one way to solve this issue by redefining the Sinput environment in which source code is wrapped by Sweave. By default, it is a simple verbatim environment which is not processed by latex for tokens. The trick is to redefine it to use the alltt environment which allows some tokens to be parsed inside the alltt environment. Note that this might lead to unwanted side effects that I am not aware of, so use with caution!

这是一个可复制的示例，可以正常工作.如果编译它，将生成一个文件，其中ref{fig1}被图形编号代替.

Here is a reproducible example that works. If you compile it, you will generate a file where ref{fig1} is replaced by the figure number.

\documentclass{article}
\usepackage{Sweave}
\usepackage{alltt}
\renewenvironment{Sinput}{\begin{alltt}}{\end{alltt}}

\begin{document}

In this document, we will create a plot using `R`, and reference its position in 
the source code.

<<produce-plot, results = hide>>=
pdf('example1.pdf')
plot(1:10, 1:10)     # Produces Figure \ref{fig1}
dev.off()
@

\begin{figure}
\includegraphics{example1.pdf}
\caption{Figure 1}
\label{fig1}
\end{figure}

\end{document}

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