Merge pull request #2960 from plotly/stacked-area

Stacked Area Charts

Author: alexcjohnson

src/components/errorbars/calc.js

@@ -43,12 +43,29 @@ function calcOneAxis(calcTrace, trace, axis, coord) {
     var computeError = makeComputeError(opts);
 
     for(var i = 0; i < calcTrace.length; i++) {
-        var calcPt = calcTrace[i],
-            calcCoord = calcPt[coord];
+        var calcPt = calcTrace[i];
+
+        var iIn = calcPt.i;
+
+        // for types that don't include `i` in each calcdata point
+        if(iIn === undefined) iIn = i;
+
+        // for stacked area inserted points
+        // TODO: errorbars have been tested cursorily with stacked area,
+        // but not thoroughly. It's not even really clear what you want to do:
+        // Should it just be calculated based on that trace's size data?
+        // Should you add errors from below in quadrature?
+        // And what about normalization, where in principle the errors shrink
+        // again when you get up to the top end?
+        // One option would be to forbid errorbars with stacking until we
+        // decide how to handle these questions.
+        else if(iIn === null) continue;
+
+        var calcCoord = calcPt[coord];
 
         if(!isNumeric(axis.c2l(calcCoord))) continue;
 
-        var errors = computeError(calcCoord, i);
+        var errors = computeError(calcCoord, iIn);
         if(isNumeric(errors[0]) && isNumeric(errors[1])) {
             var shoe = calcPt[coord + 's'] = calcCoord - errors[0],
                 hat = calcPt[coord + 'h'] = calcCoord + errors[1];