Function sampleByBuckets

src/data/sampleSeries.ts:25–110

(
  data: ReadonlyArray<DataPoint>,
  targetPoints: number,
  mode: BucketMode
)

type BucketMode = 'average' | 'max' | 'min';

function sampleByBuckets(
  data: ReadonlyArray<DataPoint>,
  targetPoints: number,
  mode: BucketMode
): ReadonlyArray<DataPoint> {
  const n = data.length;
  const threshold = clampTargetPoints(targetPoints);

  if (threshold <= 0 || n === 0) return [];
  if (threshold === 1) return [data[0]!];
  if (threshold === 2) return n >= 2 ? [data[0]!, data[n - 1]!] : [data[0]!];
  if (n <= threshold) return data;

  const lastIndex = n - 1;
  const out = new Array<DataPoint>(threshold);
  out[0] = data[0]!;
  out[threshold - 1] = data[lastIndex]!;

  const bucketSize = (n - 2) / (threshold - 2);

  for (let bucket = 0; bucket < threshold - 2; bucket++) {
    let rangeStart = Math.floor(bucketSize * bucket) + 1;
    let rangeEndExclusive = Math.min(Math.floor(bucketSize * (bucket + 1)) + 1, lastIndex);

    if (rangeStart >= rangeEndExclusive) {
      rangeStart = Math.min(rangeStart, lastIndex - 1);
      rangeEndExclusive = Math.min(rangeStart + 1, lastIndex);
    }

    let chosen: DataPoint | null = null;

    if (mode === 'average') {
      let sumX = 0;
      let sumY = 0;
      let sumSize = 0;
      let count = 0;
      let sizeCount = 0;
      for (let i = rangeStart; i < rangeEndExclusive; i++) {
        const p = data[i]!;
        const { x, y } = getXY(p);
        if (!Number.isFinite(x) || !Number.isFinite(y)) continue;
        sumX += x;
        sumY += y;
        count++;

        const size = getSize(p);
        if (typeof size === 'number' && Number.isFinite(size)) {
          sumSize += size;
          sizeCount++;
        }
      }

      if (count > 0) {
        const avgX = sumX / count;
        const avgY = sumY / count;
        if (sizeCount > 0) {
          chosen = [avgX, avgY, sumSize / sizeCount];
        } else {