coerce axes referenced by matches in layout

Author: archmoj

src/plots/cartesian/layout_defaults.js

@@ -33,6 +33,22 @@ function appendList(cont, k, item) {
     else cont[k] = [item];
 }
 
+function addMatchesInLayout(axNames, list, layoutIn) {
+    for(var j = 0; j < list.length; j++) {
+        for(var i = 0; i < list.length; i++) {
+            if(i === j) continue;
+            var e = list[i];
+            if(e === layoutIn[list[j]].matches + 'axis' && axNames.indexOf(e) === -1) {
+                // add item e to the start of the array
+                axNames = [e].concat(axNames);
+                break;
+            }
+        }
+    }
+
+    return axNames;
+}
+
 module.exports = function supplyLayoutDefaults(layoutIn, layoutOut, fullData) {
     var ax2traces = {};
     var xaMayHide = {};
@@ -122,6 +138,14 @@ module.exports = function supplyLayoutDefaults(layoutIn, layoutOut, fullData) {
     var yIds = subplots.yaxis;
     var xNames = Lib.simpleMap(xIds, id2name);
     var yNames = Lib.simpleMap(yIds, id2name);
+
+    // add axes that are referenced in the layout by other axes
+    var allKeys = Object.getOwnPropertyNames(layoutIn);
+    var xaxisKeys = allKeys.filter(function(e) { return e.indexOf('xaxis') === 0; });
+    var yaxisKeys = allKeys.filter(function(e) { return e.indexOf('yaxis') === 0; });
+    xNames = addMatchesInLayout(xNames, xaxisKeys, layoutIn);
+    yNames = addMatchesInLayout(yNames, yaxisKeys, layoutIn);
+
     var axNames = xNames.concat(yNames);
 
     // plot_bgcolor only makes sense if there's a (2D) plot!