How can I calculate the sum using TypeScript while grouping by with the reduce function in JavaScript?

Question

How can I calculate the sum using TypeScript while grouping by with the reduce function in JavaScript?

I've successfully implemented grouping by using the reduce function in typescript with my javascript. However, I'm struggling to figure out how to sum another property.

Currently, everything is grouped by the property: pacct (which is working).

The issue arises when trying to sum the property: quantity.

If anyone could provide assistance, it would be greatly appreciated.

Below is the export interface from another .ts file:

export interface TradeData {
  id: number;
  filedate: Date;
  poffic: string;
  pacct: string;
  quantity: number;
  sector: string;
  psdsC1: string;
  name: string;
  bbsymbol: string;
  last_price: number;
  deltasettlement: number;
}

Here is the code snippet where I use reduce:

const result = trades.reduce((groupedAccounts, trade) => {
  const account = trade.pacct;
  if (groupedAccounts[account] == null) groupedAccounts[account] = [];
  groupedAccounts[account].push(trade);
  return groupedAccounts;
}, {} as Record<string, TradeData[]>);

javascript reduce

Answer 1

Answer №1

For the calculation, we will initialize reduce with a starting value of 0, and then add the quantity for each trade to the total.

const sum = trades.reduce((total, trade) => total + trade.quantity, 0);

The function returns the updated value for total, which can be visualized as follows:

const callback = (total, trade) => total + trade.quantity;

const initialValue = 0;

let total = initialValue;

for (const trade of trades) {
    total = callback(total, trade);
}

To calculate the sum for each group, we iterate through each group using Object.entries:

const entries = Object.entries(groups);

We then update each entry by calculating the total sum of quantities in the group:

const summed = entries.map(([key, group]) => {
    const sum = group.reduce((total, trade) => total + trade.quantity, 0);

    return [key, sum];
});

Finally, we convert the entries back into an object using Object.fromEntries:

const transformed = Object.fromEntries(summed);

Answer 2

For the calculation, we will initialize reduce with a starting value of 0, and then add the quantity for each trade to the total.

const sum = trades.reduce((total, trade) => total + trade.quantity, 0);

The function returns the updated value for total, which can be visualized as follows:

const callback = (total, trade) => total + trade.quantity;

const initialValue = 0;

let total = initialValue;

for (const trade of trades) {
    total = callback(total, trade);
}

To calculate the sum for each group, we iterate through each group using Object.entries:

const entries = Object.entries(groups);

We then update each entry by calculating the total sum of quantities in the group:

const summed = entries.map(([key, group]) => {
    const sum = group.reduce((total, trade) => total + trade.quantity, 0);

    return [key, sum];
});

Finally, we convert the entries back into an object using Object.fromEntries:

const transformed = Object.fromEntries(summed);

How can I calculate the sum using TypeScript while grouping by with the reduce function in JavaScript?

Answer №1

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