不要在 ChartJS 折线图中按条件画线

Question

当触发条件时，我不想在两个点之间画线。

我正在使用 chartjs 时间线图。

我的条件是当y值减小时不画线，所以在这个例子中，当它从 7 变为 1 时

{x:3.5*3600, y:7},
Do not draw line between these two points
{x:4*3600, y:1},

可以用chartjs线时间图吗？

 var canvas = document.getElementById('myChart'); var config = { "options": { "scales": { "xAxes": [ { "type": 'time', "time": { "unit": 'minute', "unitStepSize": 60, }, "distribution": 'linear', "bounds": 'ticks', "ticks": { "source": 'auto', "autoSkip": true, "stepSize": 10 } } ], }, }, "data": { "labels": ['2016-04-18T00:00:00Z', '2016-04-18T23:59:00Z'], "datasets": [ { "label": "line", "type": "line", "backgroundColor": "#00b", "borderColor": "#00b", //"yAxisID": "axis4", "borderWidth": 1, "fill": false, "data": [ {x:"2016-04-18T01:00:00Z", y:1}, {x:"2016-04-18T04:00:00Z", y:2}, {x:"2016-04-18T06:00:00Z", y:3}, {x:"2016-04-18T08:00:00Z", y:7}, {x:"2016-04-18T10:00:00Z", y:1}, {x:"2016-04-18T14:00:00Z", y:3}, ] }, ] }, }; var myBarChart = Chart.Line(canvas, config);

 <script src="https://cdnjs.cloudflare.com/ajax/libs/Chart.js/2.9.0/Chart.bundle.min.js"></script> <canvas id="myChart" width="400" height="200"></canvas>

更新我试图在这两项之间添加{x:null,y:null}或null但我收到此错误

Error: 0 and 1461023970000 are too far apart with stepSize of 60 minute

在我的选择中，我有：

"data": [
  {x:"2016-04-18T01:00:00Z", y:1},
  {x:"2016-04-18T04:00:00Z", y:2},
  {x:"2016-04-18T06:00:00Z", y:3},
  {x:"2016-04-18T08:00:00Z", y:7},
  {x:null,y:null},
  {x:"2016-04-18T10:00:00Z", y:1},
  {x:"2016-04-18T14:00:00Z", y:3},
]

...

xAxes: [
    {
      type: 'time',
      time: {
        unit: 'minute',
        unitStepSize: 60,
        parser: function(date) {
          return moment(date).toLocaleString();
        }
      },
      distribution: 'linear',
      bounds: 'ticks',
      ticks: {
        source: 'auto',
        autoSkip: true,
        stepSize: 10
      }
    }
  ],

就像 chartjs 认为 null 是一个很大的价值

Answer 1

如 Chart.js 文档（请参阅spanGaps ）中所述，如果spanGaps为假（默认情况下），则具有NaN数据的点将在行中创建中断。

所以，诀窍是插入一个空点，就像你试图做的那样。 这个空点必须加时间戳，两个点之间的时间戳定义了行中的“洞”：

"data": [
  {x:"2016-04-18T01:00:00Z", y:1},
  {x:"2016-04-18T04:00:00Z", y:2},
  {x:"2016-04-18T06:00:00Z", y:3},
  {x:"2016-04-18T08:00:00Z", y:7},
  {x:"2016-04-18T08:00:00Z", y:null}, // or NaN
  {x:"2016-04-18T10:00:00Z", y:1},
  {x:"2016-04-18T14:00:00Z", y:3},
]

以这个小提琴为例： https://jsfiddle.net/t1s54gdh/

Answer 2

将 y 设置为 null，同时仍定义 x 坐标。

"data": [
  {x:"2016-04-18T01:00:00Z", y:1},
  {x:"2016-04-18T04:00:00Z", y:2},
  {x:"2016-04-18T06:00:00Z", y:3},
  {x:"2016-04-18T08:00:00Z", y:7},
  {x:"2016-04-18T08:00:01Z", y:null},
  {x:"2016-04-18T10:00:00Z", y:1},
  {x:"2016-04-18T14:00:00Z", y:3},
]