How to get text data from help pages in R?

问题

Globally, I'm interested in getting all text data from R documentations to put them in data frames and apply text mining techniques.

1. PACKAGE LEVEL: Suppose I'm interested in a package, for instance "utils" and I want to get all text data in a vector. This works:

package_d <- packageDescription("utils") package_d$Description

But not this : package_d$Details

2. FUNCTIONS LEVEL : Same problem but for the functions. I tried this without success:

   function_d <- ?utils::adist function_d$Description

3. SUB-LEVELS : I would like to extract all the details, descriptions of arguments and values of the functions of a particular package...

Thank you very much for your help !

回答1:

I couldn't find a built in one, but looking at the source for the functions that do most of the work, here's a function that can extract the text from the help page.

help_text <- function(...) {
  file <- help(...)
  path <- dirname(file)
  dirpath <- dirname(path)
  pkgname <- basename(dirpath)
  RdDB <- file.path(path, pkgname)
  rd <- tools:::fetchRdDB(RdDB, basename(file))
  capture.output(tools::Rd2txt(rd, out="", options=list(underline_titles=FALSE)))
}

You can use it with the package help pages and function help pages.

h1 <- help_text(utils)
h2 <- help_text(adist)

You'll get an array of rows from the help page. You can print them with

cat(h1, sep="\n")

来源：https://stackoverflow.com/questions/51330090/how-to-get-text-data-from-help-pages-in-r