array-xy-max-merge/src/index.js

Merge abscissa values on similar ordinates and keeps the abscissa with bigger ordinate value

/**
 * Merge abscissas values on similar ordinates and weight the group of abscissas
 * @param {object} points
 * @param {Array<number>} points.x - sorted abscissas values
 * @param {Array<number>} points.y - ordinates values
 * @param {object} [options]
 * @param {number} [options.groupWidth = 0.001] - window for abscissas to merge
 * @return {{x: Array<number>, y: Array<number>}}
 */
export default function (points, options = {}) {
    const {x, y} = points;
    const {
        groupWidth = 0.001
    } = options;

    var merged = {x: [], y: []};
    var maxAbscissa = {x: [], y: []};
    var size = 0;
    var index = 0;

    while (index < x.length) {
        if ((size === 0) || (x[index] - merged.x[size - 1] > groupWidth)) {
            maxAbscissa.x.push(x[index]);
            maxAbscissa.y.push(y[index]);
            merged.x.push(x[index]);
            merged.y.push(y[index]);
            index++;
            size++;
        } else {
            if (y[index] > maxAbscissa.y[size - 1]) {
                maxAbscissa.x[size - 1] = x[index];
                maxAbscissa.y[size - 1] = y[index];
            }
            merged.x[size - 1] = x[index];
            merged.y[size - 1] += y[index];
            index++;
        }
    }

    merged.x = maxAbscissa.x.slice();

    return merged;
}