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/*!
* jsPOS
*
* Copyright 2010, Percy Wegmann
* Licensed under the LGPLv3 license
* http://www.opensource.org/licenses/lgpl-3.0.html
*
* Enhanced by Toby Rahilly to use a compressed lexicon format as of version 0.2.
*/
function POSTagger(){
this.lexicon = POSTAGGER_LEXICON;
this.tagsMap = LEXICON_TAG_MAP;
}
/**
* Indicates whether or not this string starts with the specified string.
* @param {Object} string
*/
String.prototype.startsWith = function(string){
if (!string)
return false;
return this.indexOf(string) == 0;
}
/**
* Indicates whether or not this string ends with the specified string.
* @param {Object} string
*/
String.prototype.endsWith = function(string){
if (!string || string.length > this.length)
return false;
return this.indexOf(string) == this.length - string.length;
}
POSTagger.prototype.wordInLexicon = function(word){
var ss = this.lexicon[word];
if (ss != null)
return true;
// 1/22/2002 mod (from Lisp code): if not in hash, try lower case:
if (!ss)
ss = this.lexicon[word.toLowerCase()];
if (ss)
return true;
return false;
}
POSTagger.prototype.tag = function(words){
var ret = new Array(words.length);
for (var i = 0, size = words.length; i < size; i++) {
var ss = this.lexicon[words[i]];
// 1/22/2002 mod (from Lisp code): if not in hash, try lower case:
if (!ss)
ss = this.lexicon[words[i].toLowerCase()];
if (!ss && words[i].length == 1)
ret[i] = words[i] + "^";
if (!ss)
ret[i] = "NN";
else
ret[i] = this.tagsMap[ss][0];
}
/**
* Apply transformational rules
**/
for (var i = 0; i < words.length; i++) {
word = ret[i];
// rule 1: DT, {VBD | VBP} --> DT, NN
if (i > 0 && ret[i - 1] == "DT") {
if (word == "VBD" ||
word == "VBP" ||
word == "VB") {
ret[i] = "NN";
}
}
// rule 2: convert a noun to a number (CD) if "." appears in the word
if (word.startsWith("N")) {
if (words[i].indexOf(".") > -1) {
ret[i] = "CD";
}
// Attempt to convert into a number
if (parseFloat(words[i]))
ret[i] = "CD";
}
// rule 3: convert a noun to a past participle if words[i] ends with "ed"
if (ret[i].startsWith("N") && words[i].endsWith("ed"))
ret[i] = "VBN";
// rule 4: convert any type to adverb if it ends in "ly";
if (words[i].endsWith("ly"))
ret[i] = "RB";
// rule 5: convert a common noun (NN or NNS) to a adjective if it ends with "al"
if (ret[i].startsWith("NN") && word.endsWith("al"))
ret[i] = i, "JJ";
// rule 6: convert a noun to a verb if the preceding work is "would"
if (i > 0 && ret[i].startsWith("NN") && words[i - 1].toLowerCase() == "would")
ret[i] = "VB";
// rule 7: if a word has been categorized as a common noun and it ends with "s",
// then set its type to plural common noun (NNS)
if (ret[i] == "NN" && words[i].endsWith("s"))
ret[i] = "NNS";
// rule 8: convert a common noun to a present participle verb (i.e., a gerund)
if (ret[i].startsWith("NN") && words[i].endsWith("ing"))
ret[i] = "VBG";
}
var result = new Array();
for (i in words) {
result[i] = [words[i], ret[i]];
}
return result;
}
POSTagger.prototype.prettyPrint = function(taggedWords) {
for (i in taggedWords) {
print(taggedWords[i][0] + "(" + taggedWords[i][1] + ")");
}
}
//print(new POSTagger().tag(["i", "went", "to", "the", "store", "to", "buy", "5.2", "gallons", "of", "milk"]));
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