R 或 python 中的词形还原器(是，是，是 -> 是?)

问题描述

我不是一个[计算]语言学，所以请原谅我在这个话题上的晚饭.

I'm not a [computational] linguistic, so please excuse my supper dummy-ness in this topic.

根据维基百科，词形还原被定义为:

According to Wikipedia, lemmatisation is defined as:

语言学中的词形还原(或词形还原)是将单词的不同屈折形式组合在一起的过程，以便将它们作为单个项目进行分析.

现在我的问题是，集合 {am, is, are} 中任何成员的词形还原版本都应该是be"吗?如果没有，为什么不呢?

Now my question is, is the lemmatised version of any member of the set {am, is, are} supposed to be "be"? If not, why not?

第二个问题:我如何在 R 或 python 中获得它?我尝试过像 this 链接这样的方法，但没有一个给出be"给出are".我想至少为了对文本文档进行分类，这是有道理的.

Second question: How do I get that in R or python? I've tried methods like this link, but non of them gives "be" given "are". I guess at least for the purpose of classifying text documents, this makes sense to be true.

对于此处的任何给定演示，我也无法做到这一点.

I also couldn't do that with any of the given demos here.

我在做什么/假设错了?

What am I doing/assuming wrong?

推荐答案

所以这里有一种在 R 中实现的方法，使用 Northwestern University lemmatizer，MorphAdorner.

So here is a way to do it in R, using the Northwestern University lemmatizer, MorphAdorner.

lemmatize <- function(wordlist) {
  get.lemma <- function(word, url) {
    response <- GET(url,query=list(spelling=word,standardize="",
                                   wordClass="",wordClass2="",
                                   corpusConfig="ncf",    # Nineteenth Century Fiction
                                   media="xml"))
    content <- content(response,type="text")
    xml     <- xmlInternalTreeParse(content)
    return(xmlValue(xml["//lemma"][[1]]))
  }
  require(httr)
  require(XML)
  url <- "http://devadorner.northwestern.edu/maserver/lemmatizer"
  return(sapply(wordlist,get.lemma,url=url))
}

words <- c("is","am","was","are")
lemmatize(words)
#   is   am  was  are
# "be" "be" "be" "be"

我怀疑您知道，正确的词形还原需要了解词类(词性)、上下文正确的拼写，还取决于使用的语料库.

As I suspect you are aware, correct lemmatization requires knowledge of the word class (part of speech), contextually correct spelling, and also depends upon which corpus is being used.

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