Function meanX

docs/app/js/sanddance-app.js:137454–137456

(children)

    return a.parent === b.parent ? 1 : 2;
}
function meanX(children) {
    return children.reduce(meanXReduce, 0) / children.length;
}
function meanXReduce(x, c) {
    return x + c.x;
}