textutil.js

module.exports = textUtil = function() {

    var self = this;

    self.fieldRelevancyValues = {
        distance: {value:.10, type:'-exp'},
        nameLev : {value:.30},
        zip: {value:.40}
    }


    self.qualityScore = function (fieldValueMap){
        var score=0
        for(field in fieldValueMap){
            if(self.fieldRelevancyValues[field]){
                if(self.fieldRelevancyValues[field].type=='-exp'){
                    var raw =Math.exp(-fieldValueMap[field])
                    var val =self.fieldRelevancyValues[field].value*raw
                    console.log(val)
                    score+=val
                }else{
                    score+=self.fieldRelevancyValues[field].value*fieldValueMap[field]
                }
            }
            
        }
        return score
    }


    self.stringNormalize = function(str) {
        str = str.replace(/\&/, ' and ')
        str = str.replace(/[^A-Za-z0-9 ]+/g, '').toLowerCase()
        return str
    }

    /**
     * calculates levenstein as a percentage match
     * @param s1
     * @param s2
     */
    self.levPercent = function(s1, s2) {
        var levValue = self.lev(s1, s2)
        var big = s1.length >= s2.length ? s1 : s2
        return 1 - levValue / big.length
    }

    self.lev = function(s1, s2) {
        // Calculate Levenshtein distance between two strings
        //
        // version: 1109.2015
        // discuss at: http://phpjs.org/functions/levenshtein
        // +            original by: Carlos R. L. Rodrigues (http://www.jsfromhell.com)
        // +            bugfixed by: Onno Marsman
        // +             revised by: Andrea Giammarchi (http://webreflection.blogspot.com)
        // + reimplemented by: Brett Zamir (http://brett-zamir.me)
        // + reimplemented by: Alexander M Beedie
        // *                example 1: levenshtein('Kevin van Zonneveld', 'Kevin van Sommeveld');
        // *                returns 1: 3
        if (s1 == s2) {
            return 0;
        }

        var s1_len = s1.length;
        var s2_len = s2.length;
        if (s1_len === 0) {
            return s2_len;
        }
        if (s2_len === 0) {
            return s1_len;
        }

        // BEGIN STATIC
        var split = false;
        try {
            split = !('0')[0];
        } catch (e) {
            split = true; // Earlier IE may not support access by string index
        }
        // END STATIC
        if (split) {
            s1 = s1.split('');
            s2 = s2.split('');
        }

        var v0 = new Array(s1_len + 1);
        var v1 = new Array(s1_len + 1);

        var s1_idx = 0,
            s2_idx = 0,
            cost = 0;
        for (s1_idx = 0; s1_idx < s1_len + 1; s1_idx++) {
            v0[s1_idx] = s1_idx;
        }
        var char_s1 = '',
            char_s2 = '';
        for (s2_idx = 1; s2_idx <= s2_len; s2_idx++) {
            v1[0] = s2_idx;
            char_s2 = s2[s2_idx - 1];

            for (s1_idx = 0; s1_idx < s1_len; s1_idx++) {
                char_s1 = s1[s1_idx];
                cost = (char_s1 == char_s2) ? 0 : 1;
                var m_min = v0[s1_idx + 1] + 1;
                var b = v1[s1_idx] + 1;
                var c = v0[s1_idx] + cost;
                if (b < m_min) {
                    m_min = b;
                }
                if (c < m_min) {
                    m_min = c;
                }
                v1[s1_idx + 1] = m_min;
            }
            var v_tmp = v0;
            v0 = v1;
            v1 = v_tmp;
        }
        return v0[s1_len];
    }

    return self;

}