使用helpExtract函数将R函数的示例代码获取到knitr中 [英] Getting example codes of R functions into knitr using helpExtract function

问题描述

我想获取在knitr中使用的R函数的示例代码.可能有一种简单的方法，但是可以使用helpExtract函数尝试以下代码，该函数可以从此处获取一个>(由@AnandaMahto编写).使用我的方法，我必须查看一个函数是否具有示例"，并且必须仅包括那些具有示例"的函数.

这是一种非常低效且幼稚的方法.现在，我试图仅包括具有示例的那些函数.我尝试了以下代码，但无法正常运行.如何从R包中提取示例代码?

\documentclass{book}
\usepackage[T1]{fontenc}

\begin{document}

<< label=packages, echo=FALSE>>=
library(ggplot2)
library(devtools)
source_gist("https://gist.github.com/mrdwab/7586769")
library(noamtools)     # install_github("noamtools", "noamross")
@


\chapter{Linear Model}

<< label = NewTest1, results="asis">>=
tryCatch(
    {helpExtract(lm, section="Examples", type = "s_text");
    cat(
        "\\Sexpr{
          knit_child(
                  textConnection(helpExtract(lm, section=\"Examples\", type = \"s_text\"))
                , options = list(tidy = FALSE, eval = TRUE)
                )
             }", "\n"
        )
     }
  , error=function(e) FALSE
  )
@


\chapter{Modify properties of an element in a theme object}

<< label = NewTest2, results="asis">>=
tryCatch(
    {helpExtract(add_theme , section="Examples", type = "s_text");
    cat(
        "\\Sexpr{
          knit_child(
                  textConnection(helpExtract(add_theme , section=\"Examples\", type = \"s_text\"))
                , options = list(tidy = FALSE, eval = TRUE)
                )
             }", "\n"
        )
     }
  , error=function(e) FALSE
  )
@

\end{document}

解决方案

我已经完成了一些修改该功能的快速工作(我已经包含了

---

发生了什么变化?

• 已添加新的自变量sectionHead.这用于在helpExtract函数的调用中指定节标题.
• 该函数检查以查看相关部分在已解析的文档中是否可用.如果不是，则仅返回""(不会打印).

---

示例用法为:

<<echo = FALSE>>=
mySectionHeading <- "\\section{Some cool section title}"
@

\Sexpr{knit_child(textConnection(
helpExtract(cor, section = "Examples", type = "s_code", 
sectionHead = mySectionHeading)), 
options = list(tidy = FALSE, eval = FALSE))}

注意:由于Sexpr不允许使用大括号({)，因此我们需要在Sexpr步骤之外指定标题，这是我在隐藏代码块中完成的.

I want to get the example codes of R functions to use in knitr. There might be an easy way but tried the following code using helpExtract function which can be obtained from here (written by @AnandaMahto). With my approach I have to look whether a function has Examples or not and have to include only those functions which have Examples.

This is very inefficient and naive approach. Now I'm trying to include only those functions which have Examples. I tried the following code but it is not working as desired. How can I to extract Examples codes from an R package?

\documentclass{book}
\usepackage[T1]{fontenc}

\begin{document}

<< label=packages, echo=FALSE>>=
library(ggplot2)
library(devtools)
source_gist("https://gist.github.com/mrdwab/7586769")
library(noamtools)     # install_github("noamtools", "noamross")
@


\chapter{Linear Model}

<< label = NewTest1, results="asis">>=
tryCatch(
    {helpExtract(lm, section="Examples", type = "s_text");
    cat(
        "\\Sexpr{
          knit_child(
                  textConnection(helpExtract(lm, section=\"Examples\", type = \"s_text\"))
                , options = list(tidy = FALSE, eval = TRUE)
                )
             }", "\n"
        )
     }
  , error=function(e) FALSE
  )
@


\chapter{Modify properties of an element in a theme object}

<< label = NewTest2, results="asis">>=
tryCatch(
    {helpExtract(add_theme , section="Examples", type = "s_text");
    cat(
        "\\Sexpr{
          knit_child(
                  textConnection(helpExtract(add_theme , section=\"Examples\", type = \"s_text\"))
                , options = list(tidy = FALSE, eval = TRUE)
                )
             }", "\n"
        )
     }
  , error=function(e) FALSE
  )
@

\end{document}

解决方案

I've done some quick work modifying the function (which I've included at this Gist). The Gist also includes a sample Rnw file (I haven't had a chance to check an Rmd file yet).

The function now looks like this:

helpExtract <- function(Function, section = "Usage", type = "m_code", sectionHead = NULL) {
  A <- deparse(substitute(Function))
  x <- capture.output(tools:::Rd2txt(utils:::.getHelpFile(utils::help(A)),
                                     options = list(sectionIndent = 0)))
  B <- grep("^_", x)                      ## section start lines
  x <- gsub("_\b", "", x, fixed = TRUE)   ## remove "_\b"
  X <- rep(FALSE, length(x))              ## Create a FALSE vector
  X[B] <- 1                               ## Initialize
  out <- split(x, cumsum(X))              ## Create a list of sections
  sectionID <- vapply(out, function(x)    ## Identify where the section starts
    grepl(section, x[1], fixed = TRUE), logical(1L))

  if (!any(sectionID)) {                  ## If the section is missing...
    ""                                    ## ... just return an empty character 
  } else {                                ## Else, get that list item
    out <- out[[which(sectionID)]][-c(1, 2)]
    while(TRUE) {                         ## Remove the extra empty lines
      out <- out[-length(out)]            ##   from the end of the file
      if (out[length(out)] != "") { break }
    } 

    switch(                               ## Determine the output type
      type,
      m_code = {
        before <- "```r"
        after <- "```"
        c(sectionHead, before, out, after)
      },
      s_code = {
        before <- "<<eval = FALSE>>="
        after <- "@"
        c(sectionHead, before, out, after)
      },
      m_text = {
        c(sectionHead, paste("    ", out, collapse = "\n"))
      },
      s_text = {
        before <- "\\begin{verbatim}"
        after <- "\\end{verbatim}"
        c(sectionHead, before, out, after)
      },
      stop("`type` must be either `m_code`, `s_code`, `m_text`, or `s_text`")
    )
  }
}

---

What has changed?

• A new argument sectionHead has been added. This is used to be able to specify the section title in the call to the helpExtract function.
• The function checks to see whether the relevant section is available in the parsed document. If it is not, it simply returns a "" (which doesn't get printed).

---

Example use would be:

<<echo = FALSE>>=
mySectionHeading <- "\\section{Some cool section title}"
@

\Sexpr{knit_child(textConnection(
helpExtract(cor, section = "Examples", type = "s_code", 
sectionHead = mySectionHeading)), 
options = list(tidy = FALSE, eval = FALSE))}

Note: Since Sexpr doesn't allow curly brackets to be used ({), we need to specify the title outside of the Sexpr step, which I have done in a hidden code chunk.

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