md`Original format of spike chart. Kept for reference.
\`\`\`js
data = (await FileAttachment("population.json").json()).slice(1).map(([population, state, county]) => {
const id = state + county;
const feature = features.get(id);
return {
id,
position: feature && path.centroid(feature),
title: feature && feature.properties.name,
value: +population
};
})
\`\`\`
`