Weighted Average, JavaScript Programming Example of Weighted Average

webix.ui({
  id:"pivot",
  view:"pivot",
  datatable:{
    autowidth:true,
    autoheight:true
  },
  footer: true,
  structure: {
    rows: ["company","client"],
    columns: ["country"],
    values: [{ name:"statValue", operation:["wAver","avg"]}]
  }
});

$$("pivot").addOperation("avg", function(values, key, data, ids) {
  var sum = 0;
  for (i = 0; i < values.length; i++)
    sum+=values[i]*1;
  return values.length?(sum/values.length):0;
});

$$("pivot").addOperation("wAver", function(values, key, data, ids) {
  var i, sum = 0, weight, weightSum = 0;
  // calculate statSum and distanceSum for the leaves
  if(ids && ids.length){
    // get weighted sum for leave items
    for (i = 0; i < values.length; i++) {
      weight = $$("pivot").getItem(ids[i]).weight*1;
      sum += values[i]*weight;
      weightSum += weight;
    }
    // add calculated sum properties
    data[key+"$statSum"] = sum;
    data[key+"$weightSum"] = weightSum;
  }
  // calculation of branches
  if(data && data.data){
    for(i = 0; i < data.data.length; i++){
      var childItem = data.data[i];
      if(childItem[key+"$statSum"] && childItem[key+"$weightSum"] ){
        sum += parseFloat(childItem[key+"$statSum"]);
        weightSum += parseFloat(childItem[key+"$weightSum"]);
      }
      data[key+"$statSum"] = sum;
      data[key+"$weightSum"] = weightSum;
    }
  }
  // weighted average
  return weightSum?(sum/weightSum):0;
}, {ids: true});

$$("pivot").addTotalOperation("wAver", function(values, key, data) {
  var i, sum = 0, weightSum = 0;
  if(data && data.length){
    for(i = 0; i < data.length; i++){
      var item = data[i];
      if(item[key+"$statSum"] && item[key+"$weightSum"] ){
        sum += parseFloat(item[key+"$statSum"]);
        weightSum += parseFloat(item[key+"$weightSum"]);
      }
    }
  }
  // weighted average
  return weightSum?(sum/weightSum):0;
});

$$("pivot").parse(data);