natural

"Natural" is a general natural language facility for nodejs. Stemming, classification, phonetics and some inflection are currently supported.

It's still in the VERY (and I mean VERY) early stages, and I'm VERY (yes, again, VERY) interested in bug reports, contributions and the like.

At the moment most algorithms are English-specific but long-term some diversity is in order.

Aside from this README the only current documentation is here on my blog.

Installation

If you're just looking to consume natural without your own node application please install the NPM

npm install natural

If you're interested in contributing to natural or just hacking it then by all means fork away!

Stemmers

Currently stemming is supported via the Porter and Lancaster (Paice/Husk) algorithms.

var natural = require('natural');

this example uses a porter stemmer. "word" is returned.

console.log(natural.PorterStemmer.stem("words")); // stem a single word

attach() patches stem() and tokenizeAndStem() to String as a shortcut to PorterStemmer.stem(token). tokenizeAndStem() breaks text up into single words and returns an array of stemmed tokens.

natural.PorterStemmer.attach();
console.log("i am waking up to the sounds of chainsaws".tokenizeAndStem());
console.log("chainsaws".stem());

the same thing can be done with a lancaster stemmer

natural.LancasterStemmer.attach();
console.log("i am waking up to the sounds of chainsaws".tokenizeAndStem());
console.log("chainsaws".stem());

Naive Bayes Classifier

var natural = require('natural'), 
	classifier = new natural.BayesClassifier();

you can train the classifier on sample text. it will use reasonable defaults to tokenize and stem the text.

classifier.train([{classification: 'buy', text: "i am long qqqq"},
              {classification: 'buy', text: "buy the q's"},
              {classification: 'sell', text: "short gold"},
              {classification: 'sell', text: "sell gold"}
]);

outputs "sell"

console.log(classifier.classify('i am short silver'));

outputs "buy"

console.log(classifier.classify('i am long copper'));

classifier = new natural.BayesClassifier();

the classifier can also be trained on and classify arrays of tokens, strings, or any mixture. arrays let you use entirely custom data with your own tokenization/stemming if any at all.

classifier.train([{classification: 'hockey', text: ['puck', 'shoot']},
              {classification: 'hockey', text: 'goalies stop pucks.'},
              {classification: 'stocks', text: ['stop', 'loss']},
              {classification: 'stocks', text: 'creat a stop order'}
              ]);

console.log(classifier.classify('stop out at $100'));
console.log(classifier.classify('stop the puck, fool!'));

console.log(classifier.classify(['stop', 'out']));
console.log(classifier.classify(['stop', 'puck', 'fool']));

A classifier can also be persisted and recalled so you can reuse a training.

var classifier = new natural.BayesClassifier();

classifier.train([{classification: 'buy', text: ['long', 'qqqq']},
              {classification: 'buy', text: "buy the q's"},
              {classification: 'sell', text: "short gold"},
              {classification: 'sell', text: ['sell', 'gold']}
]);

persist to a file on disk named "classifier.json"

classifier.save('classifier.json', function(err, classifier) {
    // the classifier is saved to the classifier.json file!
});

and to recall from the classifier.json saved above:

natural.BayesClassifier.load('classifier.json', function(err, classifier) {
    console.log(classifier.classify('long SUNW'));
    console.log(classifier.classify('short SUNW'));
});

Phonetics

Phonetic matching (sounds-like) matching can be done with either the SoundEx or Metaphone algorithms

var natural = require('natural'),
    metaphone = natural.Metaphone, soundEx = natural.SoundEx;

var wordA = 'phonetics';
var wordB = 'fonetix';

test the two words to see if they sound alike

if(metaphone.compare(wordA, wordB))
    console.log('they sound alike!');

the raw phonetics are obtained with process()

console.log(metaphone.process('phonetics'));

attaching will patch String with useful methods

metaphone.attach();

soundsLike is essentially a shortcut to Metaphone.compare

if(wordA.soundsLike(wordB))
    console.log('they sound alike!');

the raw phonetics are obtained with phonetics()

console.log('phonetics'.phonetics());   

full text strings can be tokenized into arrays of phonetics similar to stemmers

console.log('phonetics rock'.tokenizeAndPhoneticize());

same module operations apply with SoundEx

if(soundEx.compare(wordA, wordB))
    console.log('they sound alike!');

console.log(soundEx.process('phonetics'));

the same String patches apply with soundex

soundEx.attach();

if(wordA.soundsLike(wordB))
    console.log('they sound alike!');
    
console.log('phonetics'.phonetics());

Inflectors

Nouns can be pluralized/singularized and numbers counted with inflectors

var natural = require('natural'),
nounInflector = new natural.NounInflector;

to pluralize a word (outputs "radii")

console.log(nounInflector.pluralize('radius'));

to singularize a word (outputs "beer")

console.log(nounInflector.singularize('beers'));

like many of the other features String can be patched to perform the operations directly. the "Noun" suffix to the methods is necessary as verbs will be supported in the future.

nounInflector.attach();
console.log('radius'.pluralizeNoun());
console.log('beers'.singularizeNoun());   

counters can also be produced from integers with CountInflector

countInflector = natural.CountInflector;

outputs "1st"

console.log(countInflector.nth(1));

outputs "111th"

console.log(countInflector.nth(111));

License

Copyright (c) 2011, Chris Umbel

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.