dataStockSplitByElementByItem = {
const primaryItemCodes = new Set(itemGroupTypes.items);
let itemEntries = Array.from(
dataForSelectedYearByElementByItem.get("Stock Variation").entries()
).filter(([itemCode]) => primaryItemCodes.has(itemCode));
itemEntries = itemEntries.map(([itemCode, d]) =>
d.year >= 2010 ? [itemCode, d] : [itemCode, { ...d, value: -d.value }]
);
const [pos, neg] = lodash.partition(
itemEntries,
([itemCode, d]) => d.value >= 0
);
const [stored, used] = [
pos,
neg.map(([itemCode, d]) => [itemCode, { ...d, value: -d.value }])
];
const copy = new Map(dataForSelectedYearByElementByItem);
copy.delete("Stock Variation");
copy.set("Stock Variation (stored)", new Map(stored));
copy.set("Stock Variation (used)", new Map(used));
return copy;
}