logistic_regression_classifier_spec.js

/*
Copyright (c) 2011, Chris Umbel

Permission is hereby granted, free of charge, to any person obtaining a copy
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*/

var natural = new require('lib/natural'),
    LogisticRegressionClassifier = natural.LogisticRegressionClassifier;

describe('logistic regression', function() {
    it('should classify with individually trained documents', function() {
        var classifier = new LogisticRegressionClassifier();
        
        classifier.addDocument(['have', 'computer'], 'IT');
        classifier.addDocument(['have', 'phone'], 'IT');
        classifier.addDocument(['computer', 'suck'], 'IT');
        classifier.addDocument(['field', 'goal'], 'sports');
        classifier.addDocument(['score', 'goal'], 'sports');
        classifier.addDocument(['great', 'speed'], 'sports');
        
        classifier.train();
        
        expect(classifier.classify(['hate', 'computer'])).toBe('IT');
        expect(classifier.classify(['score', 'please'])).toBe('sports');
    });

    it('should provide all classification scores', function() {
        var classifier = new natural.LogisticRegressionClassifier();
        classifier.addDocument(['fix', 'box'], 'computing');
        classifier.addDocument(['write', 'code'], 'computing');
        classifier.addDocument(['script', 'code'], 'computing');
        classifier.addDocument(['write', 'book'], 'literature');
        classifier.addDocument(['read', 'book'], 'literature');
        classifier.addDocument(['study', 'book'], 'literature');

        classifier.train();

        expect(classifier.getClassifications('i write code')[0].label).toBe('computing');
        expect(classifier.getClassifications('i write code')[1].label).toBe('literature');
    });

    it('should classify with arrays', function() {
        var classifier = new natural.LogisticRegressionClassifier();
        classifier.addDocument('i fixed the box', 'computing');
        classifier.addDocument('i write code', 'computing');
        classifier.addDocument('nasty script code', 'computing');
        classifier.addDocument('write a book', 'literature');
        classifier.addDocument('read a book', 'literature');
        classifier.addDocument('study the books', 'literature');

        classifier.train();

        expect(classifier.classify('a bug in the code')).toBe('computing');
        expect(classifier.classify('read all the books')).toBe('literature');
    });

    it('should serialize and deserialize a working classifier', function() {
        var classifier = new natural.LogisticRegressionClassifier();
        classifier.addDocument('i fixed the box', 'computing');
        classifier.addDocument('i write code', 'computing');
        classifier.addDocument('nasty script code', 'computing');
        classifier.addDocument('write a book', 'literature');
        classifier.addDocument('read a book', 'literature');
        classifier.addDocument('study the books', 'literature');

        var obj = JSON.stringify(classifier);
        var newClassifier = natural.LogisticRegressionClassifier.restore(JSON.parse(obj));

        newClassifier.addDocument('kick a ball', 'sports');
        newClassifier.addDocument('hit some balls', 'sports');
        newClassifier.addDocument('kick and punch', 'sports');

        newClassifier.train();

        expect(newClassifier.classify('a bug in the code')).toBe('computing');
        expect(newClassifier.classify('read all the books')).toBe('literature');
        expect(newClassifier.classify('kick butt')).toBe('sports');
    });

    it('should save and load a working classifier', function() {
        var classifier = new natural.LogisticRegressionClassifier();
        classifier.addDocument('i fixed the box', 'computing');
        classifier.addDocument('i write code', 'computing');
        classifier.addDocument('nasty script code', 'computing');
        classifier.addDocument('write a book', 'literature');
        classifier.addDocument('read a book', 'literature');
        classifier.addDocument('study the books', 'literature');
	classifier.train();

	classifier.save('lr_classifier.json', function(err) {
	    natural.LogisticRegressionClassifier.load('lr_classifier.json', null, 
						      function(err, newClassifier){
		newClassifier.addDocument('hit some balls', 'sports');
		newClassifier.addDocument('kick a ball', 'sports');
		newClassifier.addDocument('kick and punch things', 'sports');
		newClassifier.train();

		expect(newClassifier.classify('a bug in the code')).toBe('computing');
		expect(newClassifier.classify('read all the books')).toBe('literature');
		expect(newClassifier.classify('kick butt')).toBe('sports');		
		
		asyncSpecDone();
	    });
	});
    });
});