81 lines
2.6 KiB
JavaScript
81 lines
2.6 KiB
JavaScript
(function(){
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window.Smoothing = {
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/**
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* Applies both a moving average bracket and and exponential smoothing.
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* @param {array} raw The raw Y values.
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* @param {float} factor The exponential smoothing factor to apply (between o and 1).
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* @param {int} bracket The amount of datapoints to add to the backet on each side! (2 = 5 data points)
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* @return {array} The smoothed Y values.
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*/
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exponentialMovingAverage: function(raw, factor, bracket){
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var output = [];
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var smoother = new ExponentialSmoother(factor);
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//Transform each data point with the smoother.
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for (var i = 0; i < raw.length; i++){
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var input = raw[i];
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//See if we should bracket.
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if(bracket > 0){
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//Cap our start and end so it doesn't go out of bounds.
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var start = Math.max(i-bracket, 0);
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var end = Math.min(i+bracket, raw.length);
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//Push the range to our input.
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input = [];
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for(var j = start; j < end; j++){
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input.push(raw[j]);
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}
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}
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output.push(
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smoother.transform(input)
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);
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};
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return output;
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}
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};
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// Exponential Smoother class.
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var ExponentialSmoother = function(factor){
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this.currentValue = null;
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this.smoothingFactor = factor || 1;
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};
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ExponentialSmoother.prototype.transform = function(input){
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// In case our input is a bracket, first average it.
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if(input.length){
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var len = input.length;
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var sum = 0;
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for (var i = input.length - 1; i >= 0; i--)
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sum += input[i]
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input = sum/len;
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}
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// Start with our initial value.
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if(this.currentValue === null){
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this.currentValue = input;
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}
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// Our output is basically an updated value.
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return this.currentValue =
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// Weigh our current value with the smoothing factor.
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(this.currentValue * this.smoothingFactor) +
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// Add the input to it with the inverse value of the smoothing factor.
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( (1-this.smoothingFactor) * input );
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};
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})(); |