Google Charts upside-down area chart

Question

How to create an area chart which has both normal area and "upside-down" area?

Already looked at their docs, but didn't find a solution there.

The end result should look like this:

---

You can see my current status in this jsfiddle.

  google.charts.load('current', {'packages':['corechart']});
  google.charts.setOnLoadCallback(drawChart);

  function drawChart() {
    var data = google.visualization.arrayToDataTable([
      ['Year', 'Blue', 'Red'],
      ['0',  0,      20],
      ['2',  0,      20],
      ['4',  0,       20],
      ['6',  1,      19],
      ['8',  2,      18],
      ['10',  3,      17],
      ['12',  4,      16],
      ['14',  5,      15],
      ['16',  6,      14],
      ['18',  7,      13],
      ['20',  8,      12],
      ['22',  9,      11],
      ['24',  10,      10]
    ]);

    var options = {
      title: 'Company Performance',
      hAxis: {title: 'Year',  titleTextStyle: {color: '#333'}},
      vAxis: {minValue: 0}
    };

    var chart = new google.visualization.AreaChart(document.getElementById('chart_div'));
    chart.draw(data, options);
  }

Answer 1

Google Charts AreaChart从数据线向下或向上填充区域。但是基线（目前）仅适用于轴，你实际上需要两个不同的基线，一个在顶部用于一个系列，一个在底部用于另一个系列，所以你必须做一些技巧来得到你的想。

基本上，将每个系列定位到不同的轴，每个轴都有自己的基线，并使用相同的viewWindow对齐两个轴。像这样：

var options = {
  title: 'Company Performance',
  hAxis: {title: 'Year',  titleTextStyle: {color: '#333'}},
  vAxes: {
    0: {viewWindow: { min: 0, max: 20 }, baseline: 0},
    1: {viewWindow: { min: 0, max: 20 }, baseline: 20},
  },
  series: {
    1: { targetAxisIndex: 1 }
  }
};

请参阅update to your jsfiddle。