从文本中提取关键短语(1-4个单词)

Extract keyphrases from text (1-4 word ngrams)

本文关键字：1-4个单词短语文本提取更新时间：2023-09-26

从文本块中提取关键短语的最佳方法是什么?我正在写一个工具来做关键字提取:类似这样的东西。我已经为Python和Perl找到了一些库来提取n-gram，但我是在Node中编写的，所以我需要一个JavaScript解决方案。如果没有任何现有的JavaScript库，有人可以解释如何做到这一点，这样我就可以自己写吗?

我喜欢这个想法，所以我实现了它:见下文(包括描述性注释)。
预览:https://jsfiddle.net/WsKMx

/*@author Rob W, created on 16-17 September 2011, on request for Stackoverflow (http://stackoverflow.com/q/7085454/938089)
 * Modified on 17 juli 2012, fixed IE bug by replacing [,] with [null]
 * This script will calculate words. For the simplicity and efficiency,
 * there's only one loop through a block of text.
 * A 100% accuracy requires much more computing power, which is usually unnecessary
 **/

var text = "A quick brown fox jumps over the lazy old bartender who said 'Hi!' as a response to the visitor who presumably assaulted the maid's brother, because he didn't pay his debts in time. In time in time does really mean in time. Too late is too early? Nonsense! 'Too late is too early' does not make any sense.";
var atLeast = 2;       // Show results with at least .. occurrences
var numWords = 5;      // Show statistics for one to .. words
var ignoreCase = true; // Case-sensitivity
var REallowedChars = /[^a-zA-Z''-]+/g;
 // RE pattern to select valid characters. Invalid characters are replaced with a whitespace
var i, j, k, textlen, len, s;
// Prepare key hash
var keys = [null]; //"keys[0] = null", a word boundary with length zero is empty
var results = [];
numWords++; //for human logic, we start counting at 1 instead of 0
for (i=1; i<=numWords; i++) {
    keys.push({});
}
// Remove all irrelevant characters
text = text.replace(REallowedChars, " ").replace(/^'s+/,"").replace(/'s+$/,"");
// Create a hash
if (ignoreCase) text = text.toLowerCase();
text = text.split(/'s+/);
for (i=0, textlen=text.length; i<textlen; i++) {
    s = text[i];
    keys[1][s] = (keys[1][s] || 0) + 1;
    for (j=2; j<=numWords; j++) {
        if(i+j <= textlen) {
            s += " " + text[i+j-1];
            keys[j][s] = (keys[j][s] || 0) + 1;
        } else break;
    }
}
// Prepares results for advanced analysis
for (var k=1; k<=numWords; k++) {
    results[k] = [];
    var key = keys[k];
    for (var i in key) {
        if(key[i] >= atLeast) results[k].push({"word":i, "count":key[i]});
    }
}
// Result parsing
var outputHTML = []; // Buffer data. This data is used to create a table using `.innerHTML`
var f_sortAscending = function(x,y) {return y.count - x.count;};
for (k=1; k<numWords; k++) {
    results[k].sort(f_sortAscending);//sorts results
    
    // Customize your output. For example:
    var words = results[k];
    if (words.length) outputHTML.push('<td colSpan="3" class="num-words-header">'+k+' word'+(k==1?"":"s")+'</td>');
    for (i=0,len=words.length; i<len; i++) {
        
        //Characters have been validated. No fear for XSS
        outputHTML.push("<td>" + words[i].word + "</td><td>" +
           words[i].count + "</td><td>" +
           Math.round(words[i].count/textlen*10000)/100 + "%</td>");
           // textlen defined at the top
           // The relative occurence has a precision of 2 digits.
    }
}
outputHTML = '<table id="wordAnalysis"><thead><tr>' +
              '<td>Phrase</td><td>Count</td><td>Relativity</td></tr>' +
              '</thead><tbody><tr>' +outputHTML.join("</tr><tr>")+
               "</tr></tbody></table>";
document.getElementById("RobW-sample").innerHTML = outputHTML;
/*
CSS:
#wordAnalysis td{padding:1px 3px 1px 5px}
.num-words-header{font-weight:bold;border-top:1px solid #000}
HTML:
<div id="#RobW-sample"></div>
*/

我不知道JavaScript中有这样的库，但逻辑是

将文本拆分为数组
然后排序和计数

或者

拆分为数组
创建从阵列
遍历第一个数组的每一项
检查从阵列中当前项是否存在
如果不存在push它作为一个项目的键
其他增加具有键值=的值。HTH

Ivo Stoykov

function ngrams(seq, n) {
  to_return = []
  for (let i=0; i<seq.length-(n-1); i++) {
      let cur = []
      for (let j=i; j<seq.length && j<=i+(n-1); j++) {
          cur.push(seq[j])
      }
      to_return.push(cur.join(''))
  }
  return to_return
}

> ngrams(['a', 'b', 'c'], 2)
['ab', 'bc']