_getLabelSizes() {
    let labelSizes = this._labelSizes;

    if (!labelSizes) {
      const sampleSize = this.options.ticks.sampleSize;
      let ticks = this.ticks;
      if (sampleSize < ticks.length) {
        ticks = sample(ticks, sampleSize);
      }

      this._labelSizes = labelSizes = this._computeLabelSizes(ticks, ticks.length, this.options.ticks.maxTicksLimit);
    }

    return labelSizes;
  }
@return {{ first: object, last: object, widest: object, highest: object, widths: Array, heights: array }}
@private