Average //JavaScript Repository

Description

Calculates the mean, standard deviation and variance in an array.
Created: 2005.12.24

Code (Download)

//+ Carlos R. L. Rodrigues
//@ http://jsfromhell.com/array/average [rev. #1]

average = function(a){
    var r = {mean: 0, variance: 0, deviation: 0}, t = a.length;
    for(var m, s = 0, l = t; l--; s += a[l]);
    for(m = r.mean = s / t, l = t, s = 0; l--; s += Math.pow(a[l] - m, 2));
    return r.deviation = Math.sqrt(r.variance = s / t), r;
}

Example (Example)

<script type="text/javascript">
//<![CDATA[

var x = average([2, 3, 4]);

document.write(
    "average([2, 3, 4]).mean = ", x.mean, "<br />",
    "average([2, 3, 4]).deviation = ", x.deviation, "<br />",
    "average([2, 3, 4]).variance = ", x.variance
);
//]]>
</script>

Help

shuffle(vector: Array): Array
Returns an object with 3 properties, they are:
  • mean: arithmetic mean of the elements
  • variance: variance
  • deviation: standard deviation
vector
array containing numbers

Rank (Votes: 48)

3.31