rmd2md.R

#' This R script will process all R mardown files (those with in_ext file extention,
#' .rmd by default) in the current working directory. Files with a status of
#' 'processed' will be converted to markdown (with out_ext file extention, '.markdown'
#' by default). It will change the published parameter to 'true' and change the
#' status parameter to 'publish'.
#' 
#' @param path_site path to the local root storing the site files
#' @param dir_rmd directory containing R Markdown files (inputs)
#' @param dir_md directory containing markdown files (outputs)
#' @param url_images where to store/get images created from plots directory +"/" (relative to path_site)
#' @param out_ext the file extention to use for processed files.
#' @param in_ext the file extention of input files to process.
#' @param recursive should rmd files in subdirectories be processed.
#' @return nothing.
#' @author Jason Bryer <jason@bryer.org> edited by Andy South
rmd2md <- function( path_site = getwd(),
                    dir_rmd = "_Rmd",
                    dir_md = "_posts",                              
                    #dir_images = "figures",
                    url_images = "figures/",
                    out_ext='.md', 
                    in_ext='.Rmd', 
                    recursive=FALSE) {
    Sys.setlocale(category = "LC_ALL", locale = "us")
    require(knitr, quietly=TRUE, warn.conflicts=FALSE)
    
    #andy change to avoid path problems when running without sh on windows 
    files <- list.files(path=file.path(path_site,dir_rmd), pattern=in_ext, ignore.case=TRUE, recursive=recursive)
    
    for(f in files) {
        message(paste("Processing ", f, sep=''))
        content <- readLines(file.path(path_site,dir_rmd,f))
        frontMatter <- which(substr(content, 1, 3) == '---')
        if(length(frontMatter) >= 2 & 1 %in% frontMatter) {
            statusLine <- which(substr(content, 1, 7) == 'status:')
            publishedLine <- which(substr(content, 1, 10) == 'published:')
            if(statusLine > frontMatter[1] & statusLine < frontMatter[2]) {
                status <- unlist(strsplit(content[statusLine], ':'))[2]
                status <- sub('[[:space:]]+$', '', status)
                status <- sub('^[[:space:]]+', '', status)
                if(tolower(status) == 'process') {
                    #This is a bit of a hack but if a line has zero length (i.e. a
                    #black line), it will be removed in the resulting markdown file.
                    #This will ensure that all line returns are retained.
                    content[nchar(content) == 0] <- ' '
                    message(paste('Processing ', f, sep=''))
                    content[statusLine] <- 'status: publish'
                    content[publishedLine] <- 'published: true'
                    
                    #andy change to path
                    outFile <- file.path(path_site, dir_md, paste0(substr(f, 1, (nchar(f)-(nchar(in_ext)))), out_ext))
                    
                    #render_markdown(strict=TRUE)
                    #render_markdown(strict=FALSE) #code didn't render properly on blog
                    
                    #andy change to render for jekyll
                    render_jekyll(highlight = "pygments")
                    #render_jekyll(highlight = "prettify") #for javascript
                    
                    opts_knit$set(out.format='markdown') 
                    
                    # andy BEWARE don't set base.dir!! it caused me problems
                    # "base.dir is never used when composing the URL of the figures; it is 
                    # only used to save the figures to a different directory. 
                    # The URL of an image is always base.url + fig.path"
                    # https://groups.google.com/forum/#!topic/knitr/18aXpOmsumQ
                    
                    opts_knit$set(base.url = "/")
                    opts_chunk$set(fig.path = url_images)                     
                    
                    #andy I could try to make figures bigger
                    #but that might make not work so well on mobile
                    #opts_chunk$set(fig.width  = 8.5,
                    #               fig.height = 5.25)
                    
                    try(knit(text=content, output=outFile), silent=FALSE)
                    
                } else {
                    warning(paste("Not processing ", f, ", status is '", status, 
                                  "'. Set status to 'process' to convert.", sep=''))
                }
            } else {
                warning("Status not found in front matter.")
            }
        } else {
            warning("No front matter found. Will not process this file.")
        }
    }
    invisible()
}