chart.js - ChartJs - 以指定/固定间隔设置 x 轴刻度

Question

我有一个chart.js 折线图，其中x 轴标签是普通的旧数字，例如[2,4,15,45,90]，它代表此图表上的天数。我不希望 x 轴刻度反映数据标签，我希望刻度的间隔为 20。我怎样才能做到这一点？

这在我的选项中没有任何作用：

xAxes: [ {
    display: true,
    position: 'bottom',
    ticks: {
       stepSize: 20,
       min: 0,
       max: 140
    }
],

这里的例子：jsfiddle

...我发现的唯一（可怕）方法是将数字转换为日期，并在刻度回调中计算天数差异。如此处所见

标签： chart.js

Answer 1

您可以使用散点图，将数据作为单个点、具有属性的对象x和y. 要将散点图转回折线图，只需showLine: true在每个dataset.

要将数据作为单个点进行产品化，您可以在图表外部定义并使用如下方式labels转换两个值数组。Array.map()

valueArray.map((v, i) => ({ x: labels[i], y: v }))

最后要做的是定义xAxis.ticks如下：

ticks: {
  stepSize: 1,
  autoSkip: false,
  callback: value => value % 20 == 0 ? value : null,
  min: labels[0],
  max: labels[labels.length - 1],
  maxRotation: 0
},

请在下面查看您修改后的代码：

const labels = [7, 14, 21, 35, 42, 49, 56, 63, 70, 77, 84, 91, 98, 105, 119, 126];
var myChart = new Chart('myChart', {
  type: 'scatter',
  data: {    
    datasets: [{
        label: 'IC',
        data: [9432.13209267, 1899.132847, 851.2122668, 3964.48968367, 9433, 8087.04121533, 1268.34642367, 825.29800317, 4271.00722867, 1157.57453933, 4928.214994, 783.88204033, 1846.623016, 4001.84214867, 709.70201067, 3917.61792167, 688.1571182].map((v, i) => ({ x: labels[i], y: v })),
        backgroundColor: [
          'rgba(255, 99, 132, 0.2)',
          'rgba(54, 162, 235, 0.2)',
          'rgba(255, 206, 86, 0.2)',
          'rgba(75, 192, 192, 0.2)',
          'rgba(153, 102, 255, 0.2)',
          'rgba(255, 159, 64, 0.2)'
        ],
        borderColor: [
          'rgba(255,99,132,1)',
          'rgba(54, 162, 235, 1)',
          'rgba(255, 206, 86, 1)',
          'rgba(75, 192, 192, 1)',
          'rgba(153, 102, 255, 1)',
          'rgba(255, 159, 64, 1)'
        ],
        showLine: true,
        borderWidth: 1
      },
      {
        label: 'Mtb',
        data: [14241.41334667, 48348.08833, 5055.28134533, 7614.80689233, 14240, 24536.66203, 1083.99264, 144.72451603, 15968.94539333, 160.150183, 5127.77524033, 953.9963646, 0, 2989.36556, 21.32920023, 27.03159138, 60310.22952333].map((v, i) => ({ x: labels[i], y: v })),
        backgroundColor: [
          'rgba(255, 99, 132, 0.2)',
          'rgba(54, 162, 235, 0.2)',
          'rgba(255, 206, 86, 0.2)',
          'rgba(75, 192, 192, 0.2)',
          'rgba(153, 102, 255, 0.2)',
          'rgba(255, 159, 64, 0.2)'
        ],
        borderColor: [
          'rgba(255,99,132,1)',
          'rgba(54, 162, 235, 1)',
          'rgba(255, 206, 86, 1)',
          'rgba(75, 192, 192, 1)',
          'rgba(153, 102, 255, 1)',
          'rgba(255, 159, 64, 1)'
        ],
        showLine: true,
        borderWidth: 1
      }
    ]
  },
  options: {
    scales: {
      xAxes: [{
        display: true,
        position: 'bottom',
        ticks: {
          stepSize: 1,
          autoSkip: false,
          callback: value => value % 20 == 0 ? value : null,
          min: labels[0],
          max: labels[labels.length - 1],
          maxRotation: 0
        },
        // afterBuildTicks: (axis, ticks) => [0, 20, 40, 60, 80, 100, 120],
        scaleLabel: {
          display: true,
          labelString: 'Days from initial test',
          fontSize: 16
        }
      }],
      yAxes: [{
          display: true,
          position: 'left',
          ticks: {
            beginAtZero: true,
            stepSize: 10000,
            min: 0,
            max: 70000
          },
          scaleLabel: {
            display: true,
            fontSize: 16
          }
        },
        {
          display: true,
          position: 'right',
          ticks: {
            beginAtZero: true,
            stepSize: 10000,
            min: 0,
            max: 70000
          },
          scaleLabel: {
            display: true,
            fontSize: 16
          }
        },
      ]
    }
  }
});

<script src="https://cdnjs.cloudflare.com/ajax/libs/Chart.js/2.9.3/Chart.min.js"></script>
<canvas id="myChart" height="100"></canvas>