Xml R语料库中每个文档的XPath

我有一个语料库x，在R中，它是使用DirSource从一个目录创建的。每个文档都是一个文本文件，包含vBulletin论坛相关网页的完整HTML。因为它是一个线程，所以每个文档都有多个单独的帖子，我想用XPath捕获它们。XPath似乎有效，但我无法将所有捕获的节点放回语料库中

如果我的语料库有25个文档，每个文档平均有4篇文章，那么我的新语料库应该有100个文档。我想知道我是否需要做一个循环并创建一个新的语料库

这是我迄今为止的混乱工作。来自www.vbulletin.org/forum/中线程的任何源都是该结构的一个示例

#for stepping through
xt <- x[[5]]
xpath <- "//div[contains(@id,'post_message')]"

getxpath <- function(xt,xpath){
  require(XML)

  #either parse
  doc <- htmlParse(file=xt)
  #doc <- htmlTreeParse(tolower(xt), asText = TRUE, useInternalNodes = TRUE)

  #don't know which to use
  #result <- xpathApply(doc,xpath,xmlValue)
  result <- xpathSApply(doc,xpath,xmlValue)

  #clean up
  result <- gsub(pattern="\\s+",replacement=" ",x=gsub(pattern="\n|\t",replacement=" ",x=result))

  result <- c(result[1:length(result)])

  free(doc)

  #converts group of nodes into 1 data frame with numbers before separate posts
  #require(plyr)
  #xbythread <- ldply(.data=result,.fun=function(x){unlist(x)})

  #don't know what needs to be returned
  result <- Corpus(VectorSource(result))
  #result <- as.PlainTextDocument(result)

  return(result)
}

#call
x2 <- tm_map(x=x,FUN=getxpath,"//div[contains(@id,'post_message')]")

#用于单步执行
xt不久前就知道了。htmlParse需要isURL=TRUE

getxpath <- function(xt,xpath){
  require(XML);require(tm)
  x <- htmlParse(file=u,isURL=TRUE)
  resultvector <- xpathSApply(x,xpath,xmlValue)
  result <- gsub(pattern="\\s+",replacement=" ",x=gsub(pattern="\n|\t",replacement=" ",x=resultvector))
  return(result)
}

res <- getxpath("http://url.com/board.html","//xpath")

getxpath