r - 从 R 的 Rd 文件访问元素？

Question

我希望浏览一个包并发现每个函数的帮助文件中提到的作者是谁。

我寻找一个函数来从 R 的帮助文件中提取元素，并且找到了一个。我能找到的最接近的是 this post , 来自诺姆·罗斯。

有这样的功能吗？ (如果没有，我想我会破解 Noam 的代码以解析 Rd 文件，并找到我感兴趣的特定元素)。

谢谢，塔尔。

潜在代码示例:

get_field_from_r_help(topic="lm", field = "Description") #
# output:

‘lm’ is used to fit linear models. It can be used to carry out regression, single stratum analysis of variance and analysis of covariance (although ‘aov’ may provide a more convenient interface for these).

Answer 1

This document由 Duncan Murdoch 撰写的关于解析 Rd 文件的文章将会有所帮助，this SO post 也是如此。 .

根据这些，您可能会尝试以下操作:

getauthors <- function(package){
    db <- tools::Rd_db(package)
    authors <- lapply(db,function(x) {
        tags <- tools:::RdTags(x)
        if("\\author" %in% tags){
            # return a crazy list of results
            #out <- x[which(tmp=="\\author")]
            # return something a little cleaner
            out <- paste(unlist(x[which(tags=="\\author")]),collapse="")
        }
        else
            out <- NULL
        invisible(out)
        })
    gsub("\n","",unlist(authors)) # further cleanup
}

然后我们可以在一两个包上运行它:

> getauthors("knitr")
                                                                                     d:/RCompile/CRANpkg/local/3.0/knitr/man/eclipse_theme.Rd 
                                                                                                                     "  Ramnath Vaidyanathan" 
                                                                                         d:/RCompile/CRANpkg/local/3.0/knitr/man/image_uri.Rd 
                                                                                                                    "  Wush Wu and Yihui Xie" 
                                                                                      d:/RCompile/CRANpkg/local/3.0/knitr/man/imgur_upload.Rd 
                                                                              "  Yihui Xie, adapted from the imguR package by Aaron  Statham" 
                                                                                          d:/RCompile/CRANpkg/local/3.0/knitr/man/knit2pdf.Rd 
                                                                                         "  Ramnath Vaidyanathan, Alex Zvoleff and Yihui Xie" 
                                                                                           d:/RCompile/CRANpkg/local/3.0/knitr/man/knit2wp.Rd 
                                                                                                          "  William K. Morris and Yihui Xie" 
                                                                                        d:/RCompile/CRANpkg/local/3.0/knitr/man/knit_theme.Rd 
                                                                                                       "  Ramnath Vaidyanathan and Yihui Xie" 
                                                                                     d:/RCompile/CRANpkg/local/3.0/knitr/man/knitr-package.Rd 
                                                                                                            "  Yihui Xie <http://yihui.name>" 
                                                                                        d:/RCompile/CRANpkg/local/3.0/knitr/man/read_chunk.Rd 
                      "  Yihui Xie; the idea of the second approach came from  Peter Ruckdeschel (author of the SweaveListingUtils  package)" 
                                                                                       d:/RCompile/CRANpkg/local/3.0/knitr/man/read_rforge.Rd 
                                                                                                          "  Yihui Xie and Peter Ruckdeschel" 
                                                                                           d:/RCompile/CRANpkg/local/3.0/knitr/man/rst2pdf.Rd 
                                                                                                               "  Alex Zvoleff and Yihui Xie" 
                                                                                              d:/RCompile/CRANpkg/local/3.0/knitr/man/spin.Rd 
"  Yihui Xie, with the original idea from Richard FitzJohn  (who named it as sowsear() which meant to make a  silk purse out of a sow's ear)" 

也许工具:

> getauthors("tools")
                       D:/murdoch/recent/R64-3.0/src/library/tools/man/bibstyle.Rd 
                                                                "  Duncan Murdoch" 
                   D:/murdoch/recent/R64-3.0/src/library/tools/man/checkPoFiles.Rd 
                                                                "  Duncan Murdoch" 
                        D:/murdoch/recent/R64-3.0/src/library/tools/man/checkRd.Rd 
                                                  "  Duncan Murdoch, Brian Ripley" 
                     D:/murdoch/recent/R64-3.0/src/library/tools/man/getDepList.Rd 
                                                                   " Jeff Gentry " 
                      D:/murdoch/recent/R64-3.0/src/library/tools/man/HTMLlinks.Rd 
                                                    "Duncan Murdoch, Brian Ripley" 
            D:/murdoch/recent/R64-3.0/src/library/tools/man/installFoundDepends.Rd 
                                                                     "Jeff Gentry" 
                D:/murdoch/recent/R64-3.0/src/library/tools/man/makeLazyLoading.Rd 
                                                   "Luke Tierney and Brian Ripley" 
                       D:/murdoch/recent/R64-3.0/src/library/tools/man/parse_Rd.Rd 
                                                                " Duncan Murdoch " 
                     D:/murdoch/recent/R64-3.0/src/library/tools/man/parseLatex.Rd 
                                                                  "Duncan Murdoch" 
                        D:/murdoch/recent/R64-3.0/src/library/tools/man/Rd2HTML.Rd 
                                                  "  Duncan Murdoch, Brian Ripley" 
                 D:/murdoch/recent/R64-3.0/src/library/tools/man/Rd2txt_options.Rd 
                                                                  "Duncan Murdoch" 
                   D:/murdoch/recent/R64-3.0/src/library/tools/man/RdTextFilter.Rd 
                                                                "  Duncan Murdoch" 
                D:/murdoch/recent/R64-3.0/src/library/tools/man/SweaveTeXFilter.Rd 
                                                                  "Duncan Murdoch" 
                       D:/murdoch/recent/R64-3.0/src/library/tools/man/texi2dvi.Rd 
                     "  Originally Achim Zeileis but largely rewritten by R-core." 
                  D:/murdoch/recent/R64-3.0/src/library/tools/man/tools-package.Rd 
"  Kurt Hornik and Friedrich Leisch  Maintainer: R Core Team R-core@r-project.org" 
                D:/murdoch/recent/R64-3.0/src/library/tools/man/vignetteDepends.Rd 
                                                                   " Jeff Gentry " 
                 D:/murdoch/recent/R64-3.0/src/library/tools/man/vignetteEngine.Rd 
                                            "Duncan Murdoch and Henrik Bengtsson." 
                  D:/murdoch/recent/R64-3.0/src/library/tools/man/writePACKAGES.Rd 
                                                        "  Uwe Ligges and R-core."

有些函数没有作者字段，所以这只是在 getauthors 末尾调用 unlist 时删除那些，但是可以稍微修改代码以返回 NULL 值。

此外，进一步的解析将变得有点困难，因为包作者似乎以非常不同的方式使用该字段。 devtools 中只有一个作者字段。 car 中有一堆，每个都包含一个电子邮件地址。等等，等等。但这会让您获得可用信息，您应该能够进一步使用这些信息。

注意:如果您有 Rd 文件的完整路径，我的此答案的先前版本提供了一个解决方案，但如果您尝试对已安装的软件包执行此操作，则该解决方案无效。按照 Tyler 的建议，我制定了一个更完整的解决方案。