@antv/scale/src/utils/ticks.ts

Toolkit for mapping abstract data into visual representation.

const e10 = Math.sqrt(50);
const e5 = Math.sqrt(10);
const e2 = Math.sqrt(2);

export function tickIncrement(start: number, stop: number, count: number): number {
  const step = (stop - start) / Math.max(0, count);
  const power = Math.floor(Math.log(step) / Math.LN10);
  const error = step / 10 ** power;
  if (power >= 0) {
    // eslint-disable-next-line no-nested-ternary
    return (error >= e10 ? 10 : error >= e5 ? 5 : error >= e2 ? 2 : 1) * 10 ** power;
  }
  // eslint-disable-next-line no-nested-ternary
  return -(10 ** -power) / (error >= e10 ? 10 : error >= e5 ? 5 : error >= e2 ? 2 : 1);
}

export function tickStep(start: number, stop: number, count: number) {
  const step0 = Math.abs(stop - start) / Math.max(0, count);
  let step1 = 10 ** Math.floor(Math.log(step0) / Math.LN10);
  const error = step0 / step1;
  if (error >= e10) step1 *= 10;
  else if (error >= e5) step1 *= 5;
  else if (error >= e2) step1 *= 2;
  return stop < start ? -step1 : step1;
}