+    TIMEOUTS = {};

+

+// recompute values using aggregation mechanisms and custom statistics on raw data

+function recomputeAggregations(callback, errback) {

+    const attribute1 = "WAGES_TOTAL",

+        attribute2 = "POPULATION_TOTAL";

+

+    gsp.bi.stage.findStage(null, function(stage) {

+        if (!stage) return;

+

+        // use BI aggregation mechanism. Here I'm using a weighted average of attribute1 by attribute2

+        let aggregationResult = stage.tryAggregation(`round($sum(${attribute1}*${attribute2})/$sum(${attribute2}))`);

+

+        if (!aggregationResult.success) return;

+

+        let value = aggregationResult.value.test;

+

+        // custom statistical operations on raw rows. I am using Array.prototype.reduce function

+        // but feel free to use plain for loop or whatever

+

+        let customAcc = stage.rows().reduce(function(accumulated, current) {

+            accumulated.min = Math.min(accumulated.min, current[attribute1]);

+            accumulated.max = Math.max(accumulated.max, current[attribute1]);

+            return accumulated;

+        }, {

+            min: Infinity,

+            max: -Infinity

+        });

+

+        let output = `Weighted average of ${attribute1} by ${attribute2} is ${value} while min=${customAcc.min} and max=${customAcc.max}`;

+        if (typeof callback === "function")

+            callback(output);

+

+    }, function(err) {

+        if (typeof errback === "function")

+            errback(err);

+    });

+}

+

+

+// recompute statistics and update the custom chart

+function update() {

+    recomputeAggregations(updateCustomChart);

+}

+

+

+// update the custom chart

+function updateCustomChart(html) {

+    document.querySelector(".custom-chart > div.widget-chart > div.widget-content").innerHTML = html;

+}

+

+function onRenderlet(chart, filter) {

+    update();

+}

+

+// wait for the pointmap layer, store reference to it and apply customizations

+waitFor("choropleth", function(widget) {

+    let geochart = widget.chart;

+    GLOBALS.geochart = geochart;

+    // attach an event to the choropleth so each time it is refreshed our onRenderlet function will execute

+    geochart.on("renderlet", onRenderlet);

+    // initial values

+    update();

+});

+

+// waits until the widget of particular type is on stage

+// this is simplified and it should be used just once for particular chartType

+// @param {String} chartType - "choropleth", "pointmap", "table", "row", "bar", "pie", etc.

+// @param {Function} callback callback function

+// @param {Object} callback.widget first widget of particular type

+// @return {void}

+function waitFor(chartType, callback) {

+    gsp.bi.stage.findWidgets({

+        descriptors: [{

+            chartM: {

+                chart: chartType

+            }

+        }]

+    }, function(widgets) {

+        if (!widgets || !widgets[0]) {

+            TIMEOUTS[chartType] = setTimeout(function() {

+                waitFor(chartType, callback);

+            }, 500);

+        } else {

+            clearTimeout(TIMEOUTS[chartType]);

+            callback(widgets[0]);

+        }

+    });