proper keying for multiple parcoords

Author: monfera

src/traces/parcoords/attributes.js

@@ -112,6 +112,14 @@ module.exports = {
         description: 'The desired approximate tick distance (in pixels) between axis ticks on an axis.'
     },
 
+    padding: {
+        valType: 'number',
+        dflt: 80,
+        min: 0,
+        role: 'style',
+        description: 'The desired space for displaying axis labels and domain ranges around the actual parcoords.'
+    },
+
     line: extendFlat({},
         colorAttributes('line'),
         {

src/traces/parcoords/calc.js

@@ -75,6 +75,7 @@ module.exports = function calc(gd, trace) {
         tickdistance: trace.tickdistance,
         lines: trace.lines,
         line: trace.line,
+        padding: trace.padding,
         unitToColor: function(d) {
             return polylinearUnitScales.map(function(s) {
                 return s(cScale(d));

src/traces/parcoords/defaults.js

@@ -77,6 +77,7 @@ module.exports = function supplyDefaults(traceIn, traceOut, defaultColor, layout
     handleLineDefaults(traceIn, traceOut, defaultColor, layout, coerce);
 
     coerce('tickdistance');
+    coerce('padding');
 
     coerce('domain.x');
     coerce('domain.y');

src/traces/parcoords/parcoords.js

@@ -70,7 +70,7 @@ function domainToUnitScale(values) {
     return d3.scale.linear().domain(extent);
 }
 
-function model(layout, d) {
+function model(layout, d, i) {
 
     var data = d.dimensions;
 
@@ -97,7 +97,7 @@ function model(layout, d) {
     var brushCaptureWidth = d.filterbar.capturewidth || Math.min(32, brushVisibleWidth + 16);
 
     return {
-        key: Math.random(),
+        key: i,
         dimensions: data,
         tickDistance: d.tickdistance,
         unitToColor: d.unitToColor,