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Is there a nice way to extract get the R-help page from an installed package in the form of an R object (e.g a list). I would like to expose help pages in the form of standardized JSON or XML schemas. However getting the R-help info from the DB is harder than I thought.
I hacked together a while ago to get the HTML of an R help manual page. However I would rather have a general R object that contains this information, that I can render to JSON/XML/HTML, etc. I looked into the helpr package from Hadley, but this seems to be a bit of overkill for my purpose.
593
help operator in R provide access to the documentation pages for R functions, data sets, and other objects, both for packages in the standard R distribution and for contributed packages. To access documentation for the standard lm (linear model) function, for example, enter the command help(lm) or help("lm") , or ?
In the RStudio IDE you can click on any function name and press F1 , which will directly open the associated function help text in its pane.
This error usually occurs when a package has not been loaded into R via library . R does not know where to find the specified function. It's a good habit to use the library functions on all of the packages you will be using in the top R chunk in your R Markdown file, which is usually given the chunk name setup .
Edited with suggestion of Hadley
You can do this a bit easier by:
getHTMLhelp <- function(...){
thefile <- help(...)
capture.output(
tools:::Rd2HTML(utils:::.getHelpFile(thefile))
)
}
Using tools:::Rd2txt instead of tools:::Rd2HTML will give you plain text. Just getting the file (without any parsing) gives you the original Rd format, so you can write your custom parsing function to parse it into an object (see the solution of @Jeroen, which does a good job in extracting all info into a list).
This function takes exactly the same arguments as help() and returns a vector with every element being a line in the file, eg:
> head(HelpAnova)
[1] "<!DOCTYPE html PUBLIC \"-//W3C//DTD HTML 4.01 Transitional//EN\">"
[2] "<html><head><title>R: Anova Tables</title>"
[3] "<meta http-equiv=\"Content-Type\" content=\"text/html; charset=utf-8\">"
[4] "<link rel=\"stylesheet\" type=\"text/css\" href=\"R.css\">"
[5] "</head><body>"
[6] ""
Or :
> HelpGam <- getHTMLhelp(gamm,package=mgcv)
> head(HelpGam)
[1] "<!DOCTYPE html PUBLIC \"-//W3C//DTD HTML 4.01 Transitional//EN\">"
[2] "<html><head><title>R: Generalized Additive Mixed Models</title>"
[3] "<meta http-equiv=\"Content-Type\" content=\"text/html; charset=utf-8\">"
[4] "<link rel=\"stylesheet\" type=\"text/css\" href=\"R.css\">"
[5] "</head><body>"
[6] ""
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