如何将趋势线的initialValue设置为AmCharts中Value Axis的最大值？

Question

I'm using AmCharts to populate my data. I'm displaying trend lines in my chart. Is there any way to set the max value of the Value Axis as the initialValue of the trendiine ?

var trendLines = [{
  "initialValue": 1800,
  "initialCategory": 1997,
  "lineColor": "#050",
  "lineThickness": 1,
  "dashLength": 5
  "finalValue": 0,
  "finalCategory": 1997
}

Here is a code pen demo with static values in initialValue

Answer 1

If you have a static/hard-coded minimum and maximum in your value axis, you could do what Robbert mentioned in the comments. If you want to dynamically set it, you can use the init event to access the valueAxis' read-only min and max properties, which correspond to the calculated minimums and maximums of the valueAxis and add/set the trendline(s) there. Here's an example of creating a new trendline that goes from the first category and maximum value, to the last category and minimum value:

var chart = AmCharts.makeChart("chartdiv", {
  //other settings omitted
  "listeners": [{
    "event": "init",
    "method": function(e) {
      var trendline = {
        "initialValue": e.chart.valueAxes[0].max, //max axis value
        "finalValue": e.chart.valueAxes[0].min,  //min axis value
        "initialCategory": e.chart.dataProvider[0][e.chart.categoryField],
        "finalCategory":e.chart.dataProvider[e.chart.dataProvider.length - 1][e.chart.categoryField]
      };
      e.chart.trendLines.push(trendline);
      e.chart.validateNow();
    }
  }]
});

Demo