Showing sum of multiple values with amCharts - amcharts

Question

I would like to show sum of multiple values as one chart output with amCharts. I am using dataLoader with JSON to get the data. I know I have to create a function for but I couldn't understand how to get the data from the dataLoader to calculate
{
"balloonText": "[[title]] of [[valueAxis]]:[[value]]",
"lineThickness": 3,
"id": "sumValue",
"title": "sum Value",
"valueField": (function() {
var sumValues = "calculation";
return sumValues
}
this attempt is probably not correct but this is how I started
{
"balloonText": "[[title]] of [[valueAxis]]:[[value]]",
"lineThickness": 3,
"id": "LoadigTime",
"title": "Loadig Time",
"valueField": (function() {
var sumValues = (HomePageLoad + LoginToParametersLoad + ParametersLoad + AlarmsLoad + SwitchSideLoad + LoginToAdminLoad + AdminLoad) / 7;
return sumValues
})
}

Answer 1

valueField cannot be a function, only a string reference to a field in your data.
If the chart is meant to be displaying the sum of all of those fields in your data as a chart, simply add logic to your postProcess callback to create a new dataset containing your sums, e.g.
postProcess: function(data) {
var newData = [];
data.forEach(function(dataItem) {
var item = {
YOUR_CATEGORY_FIELD: dataItem.YOUR_CATEGORY_FIELD, //replace with your category field name
sum: 0
};
//loop through your item's keys and sum everything up, filtering out
//your category property
item.sum = Object.keys(dataItem).reduce(function(sum, key) {
if (key !== "YOUR_CATEGORY_FIELD") {
sum += dataItem[key]
}
return sum;
}, 0);
newData.push(item);
});
return newData;
},
// ...
graphs: [{
valueField: "sum",
// other props here
}]