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December 29, 2015 00:29
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Extracts the requested section of a function's help files from R to the console.
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helpExtract <- function(Function, section = "Usage", type = "m_code") { | |
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)) | |
X[B] <- 1 | |
out <- split(x, cumsum(X)) | |
out <- out[[which(sapply(out, function(x) | |
grepl(section, x[1], fixed = TRUE)))]][-c(1, 2)] | |
while(TRUE) { | |
out <- out[-length(out)] | |
if (out[length(out)] != "") { break } | |
} | |
switch( | |
type, | |
m_code = { | |
before <- "```r" | |
after <- "```" | |
c(before, out, after) | |
}, | |
s_code = { | |
before <- "<<>>=" | |
after <- "@" | |
c(before, out, after) | |
}, | |
m_text = { | |
paste(" ", out, collapse = "\n") | |
}, | |
s_text = { | |
before <- "\\begin{verbatim}" | |
after <- "\\end{verbatim}" | |
c(before, out, after) | |
}, | |
stop("`type` must be either `m_code`, `s_code`, `m_text`, or `s_text`") | |
) | |
} |
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R Function Help Pages | |
======================================================== | |
```{r, echo=FALSE} | |
library(devtools) | |
source_gist("https://gist.github.com/mrdwab/7586769") | |
``` | |
How do I insert this? | |
```{r echo=FALSE} | |
helpExtract(cor) | |
``` | |
```{r, echo=FALSE, results='asis'} | |
cat(helpExtract(cor), sep = "\n") | |
``` | |
```{r, echo=FALSE, results='asis'} | |
cat(helpExtract(cor, section = "Argu", type = "m_text")) | |
``` | |
Here's another section: | |
```{r, echo=FALSE, results='asis'} | |
cat(helpExtract(readChar, section = "Deta", type = "m_text")) | |
``` |
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\documentclass{article} | |
\begin{document} | |
<<echo=FALSE>>= | |
library(devtools) | |
source_gist("https://gist.github.com/mrdwab/7586769") | |
@ | |
\Sexpr{knit_child(textConnection(helpExtract(cor, section="Arg", type = "s_text")), | |
options = list(tidy = FALSE, eval = FALSE))} | |
\Sexpr{knit_child(textConnection(helpExtract(cor, type = "s_code")), | |
options = list(tidy = FALSE, eval = FALSE))} | |
<<tidy=TRUE>>= | |
## normal R code | |
args(lm) | |
@ | |
\end{document} |
Modification to deal with non-existent sections?
helpExtract <- function(Function, section = "Usage", type = "m_code") {
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(before, out, after)
},
s_code = {
before <- "<<eval = FALSE>>="
after <- "@"
c(before, out, after)
},
m_text = {
paste(" ", out, collapse = "\n")
},
s_text = {
before <- "\\begin{verbatim}"
after <- "\\end{verbatim}"
c(before, out, after)
},
stop("`type` must be either `m_code`, `s_code`, `m_text`, or `s_text`")
)
}
}
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Seems like helpExtract function does not work in R 3.1.1 and knitr 1.6.10. See here http://stackoverflow.com/q/24914419/707145.