条形图的自定义颜色：Dimple JS

如何解决条形图的自定义颜色：Dimple JS

我使用 Dimple JS 创建了一个条形图，如下所示：

var svg = dimple.newSvg("#chartContainer",590,400);

var myChart = new dimple.chart(svg,data);
myChart.setBounds(60,30,470,280)
var x = myChart.addCategoryAxis("x","Date");
var y1 = myChart.addMeasureAxis("y","Actual");
var y2 = myChart.addMeasureAxis("y","Target");

myChart.addSeries("Actual",dimple.plot.bar);

var min = myChart.addSeries("Target",dimple.plot.bubble,[x,y2]);

myChart.defaultColors = [
  new dimple.color("#e74c3c","#c0392b",1),// red
  new dimple.color("#2ecc71","#27ae60",// green
];

myChart.draw();

http://jsfiddle.net/vwz8d23o/9/

但是我需要根据值是正值（绿色）还是负值（红色）为条形和气泡着色红色和绿色。有人可以帮我实现这一目标吗？