PreKnitPostHTMLRender

Dynamize headers or R code within Rmd documents to prevent proliferation of Rmd docs for similar tasks. Add in external HTML document within rmarkdown rendered HTML doc.

Description

First pre-knitting processing, then knitr::knit, then rmarkdown::render, then post HTML-rendering processing

The current process:

    
 *.Rmd       ---------------     *.md     ---------------------  *.html
-----------> | knitr::knit | -----------> | rmarkdown::render | ----------->
             ---------------              ---------------------

preknit_knit_render_postrender:

  

*.Rmd     ------------   *.Rmd     ---------------     *.md     ---------------------    *.html    --------------  *.html
--------> | pre_knit |-----------> | knitr::knit | -----------> | rmarkdown::render | -----------> | post_render| -----------> 
          ------------             ---------------              ---------------------              --------------

1. In pre-knitting processing, function takes in a Rmd file, evaluates code chunks which are marked as between adjacent lines of @@@, and then replace these code chunks with evaluated output captured using capture.output function.

2. Function then calls knitr::knit followed by rmarkdown::render.

3. After which, in post HTML-rendering processing, function evaluates code chunks in between `%%% MY_CODE_HERE `, and then replace these code chunks with evaluated output captured using capture.output function. Typically, we want to insert an external HTML file and we can use `%%% writeLines(readLines("MY_EXTERNAL_HTML_FILE"))` within the Rmd file. This function will read in the external html file and replace this `%%% ` with contents in the html file.

Usage

preknit_knit_render_postrender(pRmdfile, outhtml = NULL)

Arguments

pRmdfile - input Rmd file

outhtml - output html file

Value

The output html file will have the codes between @@@ and/or `%%% ` code chunks evaluated.

Examples

#rmarkdown package and pandoc.exe is required to run this code

library(PreKnitPostHTMLRender)

oldwd <- getwd()
setwd(tempdir())

#pandoc.exe is required to run this code
samplermd <- tempfile('test', getwd(), '.Rmd')
addhtml <- 'test__test.html'

#generate the test Rmd file
writeLines(c('---',
'title: "Example Usage"',
'output: html_document',
'---',
'',
'This document is used for various similar reports.',
'',
'@@@',
"cat(paste('#Dynamic Header1', rnorm(1)))",
'@@@',
'',
'`%%% writeLines(readLines("test__test.html"))`',
'',
'@@@',
'cat(paste("##Dynamic Header2", rnorm(1)))',
'@@@',
'',
'Some content is invariant across different reports.'), samplermd)

#generate test html file
writeLines(c('<ul>',
'<li>Item 1</li>',
'<li>Item 2</li>',
'<li>Item 3</li>',
'</ul>'), addhtml)

#Pre-knit processing and post HTML render processing
preknit_knit_render_postrender(samplermd, "sample__html.html")

#output 'sample__html.html' is in tempdir()

setwd(oldwd)