Init from given files

examples/js/distances/normalization.js

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