Gaussian smoothing function in JavaScript

smooth.js

// Adapted from http://www.swharden.com/blog/2008-11-17-linear-data-smoothing-in-python/
var smooth = function (list, degree) {
    var win = degree*2-1;
    weight = _.range(0, win).map(function (x) { return 1.0; });
    weightGauss = [];
    for (i in _.range(0, win)) {
        i = i-degree+1;
        frac = i/win;
        gauss = 1 / Math.exp((4*(frac))*(4*(frac)));
        weightGauss.push(gauss);
    }
    weight = _(weightGauss).zip(weight).map(function (x) { return x[0]*x[1]; });
    smoothed = _.range(0, (list.length+1)-win).map(function (x) { return 0.0; });
    for (i=0; i < smoothed.length; i++) {
        smoothed[i] = _(list.slice(i, i+win)).zip(weight).map(function (x) { return x[0]*x[1]; }).reduce(function (memo, num){ return memo + num; }, 0) / _(weight).reduce(function (memo, num){ return memo + num; }, 0);
    }
    return smoothed;
}

hello, how to use this function? I face of error: Uncaught ReferenceError: _ is not defined

_ is underscore.js, so you'll need to install that and do something like this at the top of the script:

var _ = require('underscore');