使用POS标记来否定句子

Question

我正试图找到一种基于POS标记来否定句子的方法.请考虑:

include_once 'class.postagger.php';

function negate($sentence) {  
  $tagger = new PosTagger('includes/lexicon.txt');
  $tags = $tagger->tag($sentence);
  foreach ($tags as $t) {
    $input[] = trim($t['token']) . "/" . trim($t['tag']) .  " ";
  }
  $sentence = implode(" ", $input);
  $postagged = $sentence;

  // Concatenate "not" to every JJ, RB or VB
  // Todo: ignore negative words (not, never, neither)
  $sentence = preg_replace("/(\w+)\/(JJ|MD|RB|VB|VBD|VBN)\b/", "not$1/$2", $sentence);

  // Remove all POS tags
  $sentence = preg_replace("/\/[A-Z$]+/", "", $sentence);

  return "$postagged<br>$sentence";
}

顺便说一句:在这个例子中,我正在使用Ian Barber 的POS标签实现和词典.此代码运行的一个示例是:

echo negate("I will never go to their place again");
I/NN will/MD never/RB go/VB to/TO their/PRP$ place/NN again/RB 
I notwill notnever notgo to their place notagain

正如你所看到的,(并且这个问题在代码中也被注释),否定词语本身就被否定了:never变得notnever明显不应该发生.由于我的正则表达式技能不是全部,有没有办法从正则表达式中排除这些单词？

[编辑]此外,我非常欢迎你在这个否定实施中可能有的其他评论/批评,因为我确定它(仍然)有很大的缺陷:-)

Answer 1

尝试一下：

$sentence = preg_replace("/(\s)(?:(?!never|neither|not)(\w*))\/(JJ|MD|RB|VB|VBD|VBN)\b/", "$1not$2", $sentence);