javascript - AMcharts:根据值的范围设置 fillColors 字段的颜色

Question

因此，如果值在一定范围内，我想更改各个条形的颜色。我如何在 JavaScript 中执行此操作？我真的不想弄乱我的 JSON 数据。

var chart = AmCharts.makeChart( "chartdiv", {
 "type": "serial",
 "theme": "none",
 "dataProvider": [ {
   "country": "USA",
   "visits": 2025
 }, {
   "country": "China",
   "visits": 1882
 }, {
   "country": "Japan",
   "visits": 1809
 }, {
   "country": "Germany",
   "visits": 1322
 }, {
   "country": "UK",
   "visits": 1122
 }, {
   "country": "France",
   "visits": 1114
 }, {
   "country": "India",
   "visits": 984
 }, {
   "country": "Spain",
   "visits": 711
 }, {
   "country": "Netherlands",
   "visits": 665
 }, {
   "country": "Russia",
   "visits": 580
 }, {
   "country": "South Korea",
   "visits": 443
 }, {
   "country": "Canada",
   "visits": 441
 }, {
   "country": "Brazil",
   "visits": 395
 } ],
 "valueAxes": [ {
   "gridColor": "#FFFFFF",
   "gridAlpha": 0.2,
   "dashLength": 0
 } ],
 "gridAboveGraphs": true,
 "startDuration": 1,
 "graphs": [ {
   "balloonText": "[[category]]: <b>[[value]]</b>",
   "fillAlphas": 0.8,
   "lineAlpha": 0.2,
   "fillColors": changeColour,
   "type": "column",
   "valueField": "visits"
 } ],
 "chartCursor": {
   "categoryBalloonEnabled": false,
   "cursorAlpha": 0,
   "zoomable": false
 },
 "categoryField": "country",
 "categoryAxis": {
   "gridPosition": "start",
   "gridAlpha": 0,
   "tickPosition": "start",
   "tickLength": 20
 },
 "export": {
   "enabled": true
 }

  } );

  function changeColour(value){
  /*var colour;
       if (0 <= value && value <= 40){
    colour = "#ff3333";
   } else if (41 <= value && value <= 66){
    colour = "#ff751a";
   } else if (value > 66){
    colour = "#009933";
   }*/
  //return colour;
  return "#ff3333";
  }

我创建了一个函数，如果值在某个数字内，我试图返回颜色，但这不起作用。

这是一个我正在弄清楚如何做到这一点的示例。 https://jsfiddle.net/ckylec4/8to7hghj/2/

Answer 1

图表不支持自定义函数作为颜色格式化程序。

可能唯一的解决方案是预处理数据，并为每个数据点设置 fillColorsField。

AmCharts.addInitHandler()似乎是所有类型预处理的完美工具。

让我们“发明”一个我们将使用的新参数fillColorsFunction。我们可以为此重用您的函数 changeColour:

"graphs": [{
  "balloonText": "[[category]]: <b>[[value]]</b>",
  "fillAlphas": 0.8,
  "lineAlpha": 0.2,
  "fillColorsFunction": changeColour,
  "type": "column",
  "valueField": "visits"
}],

现在，让我们创建一个使用它的“插件”:

/**
 * Plugin: checks for graphs with "fillColorsFunction"
 */
AmCharts.addInitHandler(function(chart) {

  // iterate thorugh all graphs and check if they have
  // fillColorsFunction set
  for (i = 0; i < chart.graphs.length; i++) {
    var graph = chart.graphs[i];
    if (graph.fillColorsFunction !== undefined) {
      // iterate thorugh all of the data and add color
      graph.fillColorsField = graph.valueField + "FillColor";
      for (var x = 0; x < chart.dataProvider.length; x++) {
        var dp = chart.dataProvider[x];
        dp[graph.fillColorsField] = graph.fillColorsFunction.call(this, dp[graph.valueField]);
      }
    }
  }

}, ["serial"]);

这是整个工作内容: http://codepen.io/team/amcharts/pen/963bb83fa1d3c146cd337b981e6c9a11

<小时/>

如果您使用 Data Loader 插件，则可以将相同的代码移至其 complete 中处理程序:

"dataLoader": {
  "url": "data.php",
  "complete": function( chart ) {
    // iterate thorugh all graphs and check if they have
    // fillColorsFunction set
    for ( i = 0; i < chart.graphs.length; i++ ) {
      var graph = chart.graphs[ i ];
      if ( graph.fillColorsFunction !== undefined ) {
        // iterate thorugh all of the data and add color
        graph.fillColorsField = graph.valueField + "FillColor";
        for ( var x = 0; x < chart.dataProvider.length; x++ ) {
          var dp = chart.dataProvider[ x ];
          dp[ graph.fillColorsField ] = graph.fillColorsFunction.call( this, dp[ graph.valueField ] );
        }
      }
    }
  }
}