R functions help into a quarto document

Question

The following code gives the examples r codes along their output for first six topics from stats r library.

---
title: "Help"
format: pdf
---

```{r}
#| echo: false
#| class-output: r
library(purrr)
map(
      .x             = ls("package:stats", all = FALSE)[1:6] 
    , .f             = example
    , package        = "stats"
    , character.only = TRUE
    , type           = "html"
    )
```

I want to tweak this output a little bit.

Expected Output

Wondering how to add each topic title as a section and then its corresponding code and output.

Edited

The helpExtract from SOfun r package can be used to extract specified portions of r help files for use in sweave or r-markdown documents.

remotes::install_github("mrdwab/SOfun")

library(SOfun)

helpExtract(
    Function = acf
  , section  = c("Description", "Usage", "Arguments", "Details", "Value", "Examples")[1] 
  , type     = c("m_code", "m_text", "s_code", "s_text")[2]
  )

However, can't figured out how to use this function to extract topic title.

Edited (2023-04-19)

@Julian's solution is effective for the stats r package, but it does not function properly with the meta r package. When attempting to use it with the meta r package, the following error is generated:

Error in purrr::map():i In index: 1.Caused by error in file():! cannot open the connectionError in vctrs_vec_compat(.y, .purrr_user_env): object 'topic_title' not foundError in cat(res, sep = "\n"): object 'res' not found1

Answer 1

Is this what you want? I added a toc to see whether the chapters are as intended (code idea comes from here and here):

---
title: "Help"
format: pdf
toc: true
number-sections: true
---


```{r}
#| echo: false

# https://stackoverflow.com/questions/8379570/get-functions-title-from-documentation
pkg_topic <- function(package, topic, file = NULL) {
  # Find "file" name given topic name/alias
  if (is.null(file)) {
    topics <- pkg_topics_index(package)
    topic_page <- subset(topics, alias == topic, select = file)$file

    if(length(topic_page) < 1)
      topic_page <- subset(topics, file == topic, select = file)$file

    stopifnot(length(topic_page) >= 1)
    file <- topic_page[1]    
  }

  rdb_path <- file.path(system.file("help", package = package), package)
  tools:::fetchRdDB(rdb_path, file)
}

pkg_topics_index <- function(package) {
  help_path <- system.file("help", package = package)

  file_path <- file.path(help_path, "AnIndex")
  if (length(readLines(file_path, n = 1)) < 1) {
    return(NULL)
  }

  topics <- read.table(file_path, sep = "\t", 
    stringsAsFactors = FALSE, comment.char = "", quote = "", header = FALSE)

  names(topics) <- c("alias", "file") 
  topics[complete.cases(topics), ]
}
```



```{r}
#| output: asis
#| echo: false

topic <- ls("package:stats", all = FALSE)[1:6]
topic_title <- topic |> 
  purrr::map( \(function_name) {
    target <- gsub("^.+/library/(.+)/help.+$", "\\1", utils:::index.search("stats", 
                                                                  find.package()))
    doc.txt <- pkg_topic(target, function_name)  # assuming both of Hadley's functions are here

    return(doc.txt[[1]][[1]][1])
  })
  


res <- purrr::map2_chr(topic, topic_title, \(topic, topic_title) {
    knitr::knit_child(text = c(
      "# `r topic_title`",
      "", 
      "```{r}",
      "#| echo: false",
      "#| class-output: r",
      "example(topic, package = 'stats', character.only = TRUE, type = 'html')",
      "```",
      "",
      ""
    ), envir = environment(), quiet = TRUE)
  })

cat(res, sep = '\n')
```