[Python/Pandas] 리트코드 1327. List the Products Ordered in a Period

문제

Table: Products
+------------------+---------+
| Column Name      | Type    |
+------------------+---------+
| product_id       | int     |
| product_name     | varchar |
| product_category | varchar |
+------------------+---------+

product_id is the primary key (column with unique values) for this table.
This table contains data about the company's products.

Table: Orders
+---------------+---------+
| Column Name   | Type    |
+---------------+---------+
| product_id    | int     |
| order_date    | date    |
| unit          | int     |
+---------------+---------+

This table may have duplicate rows.
product_id is a foreign key (reference column) to the Products table.
unit is the number of products ordered in order_date.
 
Write a solution to get the names of products that have at least 100 units ordered in February 2020 and their amount.
Return the result table in any order.

 

https://leetcode.com/problems/list-the-products-ordered-in-a-period/description/?lang=pythondata

예시

Input: 
Products table:
+-------------+-----------------------+------------------+
| product_id  | product_name          | product_category |
+-------------+-----------------------+------------------+
| 1           | Leetcode Solutions    | Book             |
| 2           | Jewels of Stringology | Book             |
| 3           | HP                    | Laptop           |
| 4           | Lenovo                | Laptop           |
| 5           | Leetcode Kit          | T-shirt          |
+-------------+-----------------------+------------------+
Orders table:
+--------------+--------------+----------+
| product_id   | order_date   | unit     |
+--------------+--------------+----------+
| 1            | 2020-02-05   | 60       |
| 1            | 2020-02-10   | 70       |
| 2            | 2020-01-18   | 30       |
| 2            | 2020-02-11   | 80       |
| 3            | 2020-02-17   | 2        |
| 3            | 2020-02-24   | 3        |
| 4            | 2020-03-01   | 20       |
| 4            | 2020-03-04   | 30       |
| 4            | 2020-03-04   | 60       |
| 5            | 2020-02-25   | 50       |
| 5            | 2020-02-27   | 50       |
| 5            | 2020-03-01   | 50       |
+--------------+--------------+----------+
Output: 
+--------------------+---------+
| product_name       | unit    |
+--------------------+---------+
| Leetcode Solutions | 130     |
| Leetcode Kit       | 100     |
+--------------------+---------+
Explanation: 
Products with product_id = 1 is ordered in February a total of (60 + 70) = 130.
Products with product_id = 2 is ordered in February a total of 80.
Products with product_id = 3 is ordered in February a total of (2 + 3) = 5.
Products with product_id = 4 was not ordered in February 2020.
Products with product_id = 5 is ordered in February a total of (50 + 50) = 100.

문제 풀이

import pandas as pd

def list_products(products: pd.DataFrame, orders: pd.DataFrame) -> pd.DataFrame:
    filtered = orders.loc[(orders['order_date'] >= '2020-02-01') & (orders['order_date'] < '2020-03-01')]
    grouped = filtered.groupby('product_id')['unit'].sum().reset_index()
    merged = pd.merge(products, grouped, how='inner', on='product_id')
    result = merged.loc[merged['unit'] >= 100][['product_name', 'unit']]
    return result

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