Method indicesOfNearest

src/model/Series.ts:472–520

* Retrieve the index of nearest value in the view coordinate. * Data position is compared with each axis's dataToCoord. * * @param axisDim axis dimension * @param dim data dimension * @param value * @param [maxDistance=Infinity] The maximum distance in view coordinate s

(axisDim: DimensionName, dim: DimensionLoose, value: number, maxDistance?: number)

     *         the same value, they are put to the result.
     */
    indicesOfNearest(axisDim: DimensionName, dim: DimensionLoose, value: number, maxDistance?: number): number[] {
        const data = this.getData();
        const coordSys = this.coordinateSystem;
        const axis = coordSys && coordSys.getAxis(axisDim);
        if (!coordSys || !axis) {
            return [];
        }
        const targetCoord = axis.dataToCoord(value);

        if (maxDistance == null) {
            maxDistance = Infinity;
        }

        const nearestIndices: number[] = [];
        let minDist = Infinity;
        let minDiff = -1;
        let nearestIndicesLen = 0;

        // Performance-sensitive on large data (triggered by `tooltip`/`axisPointer` frequently).
        const dimIdx = data.getDimensionIndex(dim);
        const store = data.getStore();
        for (let idx = 0, len = store.count(); idx < len; idx++) {
            const dimValue = store.get(dimIdx, idx);
            const dataCoord = axis.dataToCoord(dimValue);
            const diff = targetCoord - dataCoord;
            const dist = Math.abs(diff);
            if (dist <= maxDistance) {
                // When the `value` is at the middle of `this.get(dim, i)` and `this.get(dim, i+1)`,
                // we'd better not push both of them to `nearestIndices`, otherwise it is easy to
                // get more than one item in `nearestIndices` (more specifically, in `tooltip`).
                // So we choose the one that `diff >= 0` in this case.
                // But if `this.get(dim, i)` and `this.get(dim, j)` get the same value, both of them
                // should be push to `nearestIndices`.
                if (dist < minDist
                    || (dist === minDist && diff >= 0 && minDiff < 0)
                ) {
                    minDist = dist;
                    minDiff = diff;
                    nearestIndicesLen = 0;
                }
                if (diff === minDiff) {
                    nearestIndices[nearestIndicesLen++] = idx;
                }
            }
        }

        nearestIndices.length = nearestIndicesLen;
        return nearestIndices;
    }

    /**
     * Default tooltip formatter