sentiment-multilang/index.js

Multilanguage AFINN-based sentiment analysis for Node.js

/*
* Multilanguage AFINN-based sentiment analysis for Node.js
*/

// Dependencies
var afinn = require('./lib/AFINN.js');

function tokenize(input) {
    return input
        .toLowerCase()
        .replace(/^\s+|^0-9+|[^a-z-úñäâàáéèëêïîíìöôùüûœç\- ]+/g, '')
        .replace('/ {2,}/',' ')
        .split(' ');
};

// Performs sentiment analysis on the provided input 'phrase'
module.exports = function(phrase, lang, callback) {
    // Parse arguments
    if (typeof phrase === 'undefined') phrase = '';
    if ((typeof(lang) === 'undefined') || !afinn["langs"][lang]) lang = 'unknown';
    if (typeof callback === 'undefined') callback = null;
    
    // Storage objects
    var tokens      = tokenize(phrase),
        score       = 0,
        words       = [],
        positive    = [],
        negative    = [];
    
    // Iterate over tokens if language is knowed
    var len = tokens.length;
    if (lang !== 'unknown') {
        while (len--) {
            // var prevobj = (len > 0) ? String(tokens[len-1]): "";
            var negation = (afinn["negations"][lang] && afinn["negations"][lang][tokens[len-1]]) ? -1 : 1;
            var obj = afinn["truncated"][lang] ? tokens[len].replace(/[aeiouúäâàáéèëêïîíìöôùüû]$/, "") : String(tokens[len]);
            var item = Number(afinn[lang][obj]);
            if (!afinn[lang][obj]) continue;
            
            words.push(obj);
            if (item > 0) positive.push(obj);
            if (item < 0) negative.push(obj);
            score += item*negation;
        }
    }
    
    // Handle optional async interface
    var result = {
        score:          score,
        comparative:    score / tokens.length,
        vote:           'neutral',
        tokens:         tokens,
        words:          words,
        positive:       positive,
        negative:       negative,
        language:       lang
    };
    // Classify text as positive, negative or neutral.
    if (result.score > 0) { result.vote = 'positive'; }
    else if (result.score < 0) { result.vote = 'negative'; }
    
    if (callback === null) return result;
    process.nextTick(function () {
        callback(null, result);
    });
};