decode() to XML (argument to="xml")

[ablaette]

As of now, the decode() method can produce data.table and AnnotatedPlainTextDocument output. Many users may find the option useful to decode to XML. This is a function that I have written for this purpose in a specific context. It would have to be adapted to be generic.

make_collection_xml <- function(newspaper, year){
  matching_min <- matching[corpus == newspaper][grepl(year, article_date)]
  articles <- corpus(corpus_id) %>% 
    subset(article_id %in% matching_min[["article_id"]]) %>% 
    split(s_attribute = "article_id", progress = interactive(), verbose = FALSE)
  
  articles_dt <- pblapply(
    articles,
    function(article)
      decode(
        article,
        to = "data.table",
        p_attributes = "word",
        s_attributes = "s",
        verbose = FALSE
      ),
    cl = NULL
  )
  
  articles_xml <- pblapply(
    articles_dt,
    function(dt){
      dt[, "tab" := sprintf('<w cpos="%s">%s</w>', dt[["cpos"]], dt[["word"]])]
      
      sentences <- lapply(
        split(dt, by = "s"),
        function(s)
          sprintf(
            '<s struc="%d">\n%s\n</s>',
            s[["s"]][1],
            paste(s[["tab"]], collapse = "\n")
          )
      )
      
      sprintf(
        "<article>\n%s\n</article>",
        paste(unlist(sentences), collapse = "\n")
      )
    },
    cl = parallel::detectCores() - 2L
  )
  sprintf(
    '<collection newspaper="%s" year="%s">\n%s\n</collection>\n',
    newspaper,
    year,
    paste(unlist(articles_xml), collapse = "\n")
  )
}