Function determineUnitForAutoTicks

src/scales/scale.time.js:87–100

* Figures out what unit results in an appropriate number of auto-generated ticks * @param {Unit} minUnit * @param {number} min * @param {number} max * @param {number} capacity * @return {object}

(minUnit, min, max, capacity)

 * @return {object}
 */
function determineUnitForAutoTicks(minUnit, min, max, capacity) {
  const ilen = UNITS.length;

  for (let i = UNITS.indexOf(minUnit); i < ilen - 1; ++i) {
    const interval = INTERVALS[UNITS[i]];
    const factor = interval.steps ? interval.steps : Number.MAX_SAFE_INTEGER;

    if (interval.common && Math.ceil((max - min) / (factor * interval.size)) <= capacity) {
      return UNITS[i];
    }
  }

  return UNITS[ilen - 1];
}

/**
 * Figures out what unit to format a set of ticks with