91 lines
2.5 KiB
JavaScript
91 lines
2.5 KiB
JavaScript
/**
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* Calculate the values that are used for normalizing the data.
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* @param {array} nodes
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* @return {object} that contains the normalization parameters.
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*/
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function calculateNormalization (nodes) {
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var STANDARD_DEV = 2.0,
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properties = Object.keys(nodes[0]),
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sums = calculateSums(nodes, properties),
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average = [],
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sigma = [];
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// For each property, calculate mean and sigma.
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for (var i = 0; i < properties.length; i++) {
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var avg = sums.sumOfVal[i] / nodes.length;
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average[i] = avg;
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sigma[i] = Math.sqrt((sums.sumOfSq[i] - (nodes.length * Math.pow(avg, 2))) / nodes.length);
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}
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return {
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avg: average,
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sig: sigma,
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st_d: standardDevation(nodes, properties, average)
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};
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}
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function standardDevation (nodes, properties, avg) {
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var stDev = new Array(properties.length).fill(0);
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for (var i = 0; i < properties.length; i++) {
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var sum = 0;
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nodes.forEach(function (node) {
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var val = node[properties[i]];
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var parsedDate = Date.parse(val);
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var propAvg = avg[i];
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if (isNaN(val) && !isNaN(parsedDate)) {
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val = parsedDate.valueOf();
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} else if (isNumeric(val)) {
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val = parseFloat(val);
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// Ignore the strings.
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} else {
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val = 0;
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}
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sum += Math.pow(val - propAvg, 2);
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});
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stDev[i] = Math.sqrt(sum / nodes.length);
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}
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return stDev;
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}
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// Calculate the sum of values and the squared sum
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/**
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* Calculate the sums of each property.
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* @param {array} nodes
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* @param {array} properties - list of properties
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* @return {object} that contains arrays with sum of values
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* and the squared sums.
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*/
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function calculateSums (nodes, properties) {
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var sumOfValues = new Array(properties.length).fill(0),
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sumOfSquares = new Array(properties.length).fill(0);
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// Calculate the sums for each node.
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nodes.forEach(function (node) {
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for (var i = 0; i < properties.length; i++) {
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var val = node[properties[i]];
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var parsedDate = Date.parse(val);
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if (isNaN(val) && !isNaN(parsedDate)) {
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sumOfValues[i] += parsedDate.valueOf();
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sumOfSquares[i] += Math.pow(parsedDate.valueOf(), 2);
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} else if (isNumeric(val)) {
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sumOfValues[i] += parseFloat(val);
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sumOfSquares[i] += Math.pow(parseFloat(val), 2);
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// Ignore the strings.
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} else {
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sumOfValues[i] += 0;
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sumOfSquares[i] += 0;
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}
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}
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});
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return {
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sumOfVal: sumOfValues,
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sumOfSq: sumOfSquares
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};
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}
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