accumulated = {
let accum = {};
authorArray.forEach(author => {
accum[author] = data[0][author];
});
return data.map((d, i) => {
if (i == 0) return d;
let acc = {
date: d.date
};
authorArray.forEach(author => {
accum[author] += d[author];
acc[author] = accum[author];
});
return acc;
});
}