bivariateClass = {
const h = human.scale("color").domain;
const c = cow.scale("color").domain;
return (value) => {
if (!value) return undefined;
const { human: a, cow: b } = value;
return [
isNaN(a) ? a : +(a > h[0]) + (a > h[1]),
isNaN(b) ? b : +(b > c[0]) + (b > c[1])
];
};
}