[Python/Pandas] 리트코드 1587. Bank Account Summary II

문제

Table: Users
+--------------+---------+
| Column Name  | Type    |
+--------------+---------+
| account      | int     |
| name         | varchar |
+--------------+---------+
account is the primary key (column with unique values) for this table.
Each row of this table contains the account number of each user in the bank.
There will be no two users having the same name in the table.

 Table: Transactions
+---------------+---------+
| Column Name   | Type    |
+---------------+---------+
| trans_id      | int     |
| account       | int     |
| amount        | int     |
| transacted_on | date    |
+---------------+---------+
trans_id is the primary key (column with unique values) for this table.
Each row of this table contains all changes made to all accounts.
amount is positive if the user received money and negative if they transferred money.
All accounts start with a balance of 0.

 

Write a solution to report the name and balance of users with a balance higher than 10000. The balance of an account is equal to the sum of the amounts of all transactions involving that account.

Return the result table in any order.

 

https://leetcode.com/problems/bank-account-summary-ii/description/?lang=pythondata

예시

Input: 
Users table:
+------------+--------------+
| account    | name         |
+------------+--------------+
| 900001     | Alice        |
| 900002     | Bob          |
| 900003     | Charlie      |
+------------+--------------+
Transactions table:
+------------+------------+------------+---------------+
| trans_id   | account    | amount     | transacted_on |
+------------+------------+------------+---------------+
| 1          | 900001     | 7000       |  2020-08-01   |
| 2          | 900001     | 7000       |  2020-09-01   |
| 3          | 900001     | -3000      |  2020-09-02   |
| 4          | 900002     | 1000       |  2020-09-12   |
| 5          | 900003     | 6000       |  2020-08-07   |
| 6          | 900003     | 6000       |  2020-09-07   |
| 7          | 900003     | -4000      |  2020-09-11   |
+------------+------------+------------+---------------+
Output: 
+------------+------------+
| name       | balance    |
+------------+------------+
| Alice      | 11000      |
+------------+------------+
Explanation: 
Alice's balance is (7000 + 7000 - 3000) = 11000.
Bob's balance is 1000.
Charlie's balance is (6000 + 6000 - 4000) = 8000.

문제 풀이

import pandas as pd

def account_summary(users: pd.DataFrame, transactions: pd.DataFrame) -> pd.DataFrame:
    # account 열 기준으로 groupby 후 amount 열의 합을 balance 열로 집계
    summary = transactions.groupby('account', as_index=False).agg(balance=('amount', 'sum'))
    
    # account 열 기준으로 users와 summary 병합
    merged = pd.merge(users, summary, on='account', how='left')
    
    # balance가 10000 이상인 행만 필터링
    filtered = merged.loc[merged['balance']>10000]
    
    # 출력 요구 형식에 맞추어 account 열 제외
    result = filtered.drop('account', axis=1)
    return result

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