[Python/Pandas] 리트코드 183. Customers Who Never Order

문제

Table: Customers
+-------------+---------+
| Column Name | Type    |
+-------------+---------+
| id          | int     |
| name        | varchar |
+-------------+---------+

id is the primary key (column with unique values) for this table.
Each row of this table indicates the ID and name of a customer.

Table: Orders
+-------------+------+
| Column Name | Type |
+-------------+------+
| id          | int  |
| customerId  | int  |
+-------------+------+

id is the primary key (column with unique values) for this table.
customerId is a foreign key (reference columns) of the ID from the Customers table.
Each row of this table indicates the ID of an order and the ID of the customer who ordered it.

Write a solution to find all customers who never order anything.
Return the result table in any order.

 

https://leetcode.com/problems/customers-who-never-order/description/?lang=pythondata

예시

Input: 
Customers table:
+----+-------+
| id | name  |
+----+-------+
| 1  | Joe   |
| 2  | Henry |
| 3  | Sam   |
| 4  | Max   |
+----+-------+
Orders table:
+----+------------+
| id | customerId |
+----+------------+
| 1  | 3          |
| 2  | 1          |
+----+------------+
Output: 
+-----------+
| Customers |
+-----------+
| Henry     |
| Max       |
+-----------+

문제 풀이

import pandas as pd

def find_customers(customers: pd.DataFrame, orders: pd.DataFrame) -> pd.DataFrame:
    merged = pd.merge(customers, orders, left_on = 'id', right_on = 'customerId', how='left')
    result = merged.loc[merged['customerId'].isnull(), ['name']]
    result = result.rename(columns={'name':'Customers'})
    return result

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혹 더 좋은 방법이 있거나 오류가 있다면 편하게 말씀 부탁드립니다.