echarts 根据时间跨度计算时间轴间隔

最最直接，也最根本的计算方法，应该是跟 平均数相关，确定要显示多少个数据，然后总的时间 / 要显示的个数，是这么的算法吧。

看到网上的另外一种方法

class CalculateScale {
  private min;
  private max;
  private maxTicks = 40;
  private tickSpacing;
  private range;
  private fitMin;
  private fitMax;

  constructor (start, end) {
    this.min = start;
    this.max = end;
    this.calculate();
  }

  getFitNumber = (range) => {
    let exponent;
    let fraction;
    let fitFraction;
    exponent = Math.floor(Math.log10(range));
    fraction = range / Math.pow(10, exponent);
    if (fraction <= 1) {
      fitFraction = 1;
    } else if (fraction <= 2) {
      fitFraction = 2;
    } else if (fraction <= 5) {
      fitFraction = 5;
    } else {
      fitFraction = 10;
    }
    return fitFraction * Math.pow(10, exponent);
  };

  calculate = () => {
    this.range = this.getFitNumber(this.max - this.min);
    this.tickSpacing = this.getFitNumber(this.range / (this.maxTicks - 1));
    this.fitMin = Math.floor(this.min / this.tickSpacing) * this.tickSpacing;
    this.fitMax = Math.ceil(this.max / this.tickSpacing) * this.tickSpacing;
  };

  setMinMaxPoint = (min, max) => {
    this.min = min;
    this.max = max;
    this.calculate();
  };

  setMaxTicks = (maxTicks) => {
    this.maxTicks = maxTicks;
    this.calculate();
  };

  getTickSpacing = () =>  {
    return this.tickSpacing;
  };

  getFitMin = () => {
    return this.fitMin;
  };

  getFitMax = () => {
    return this.fitMax;
  };
}

export default CalculateScale;

后面可以继续再想想这种方法