Question

2890. 重塑数据：融合

English Version

题目描述

DataFrame report
+-------------+--------+
| Column Name | Type   |
+-------------+--------+
| product   | object |
| quarter_1   | int  |
| quarter_2   | int  |
| quarter_3   | int  |
| quarter_4   | int  |
+-------------+--------+

编写一个解决方案，将数据 重塑 成每一行表示特定季度产品销售数据的形式。

结果格式如下例所示：

 

示例 1：

输入：
+-------------+-----------+-----------+-----------+-----------+
| product   | quarter_1 | quarter_2 | quarter_3 | quarter_4 |
+-------------+-----------+-----------+-----------+-----------+
| Umbrella  | 417     | 224     | 379     | 611     |
| SleepingBag | 800     | 936     | 93    | 875     |
+-------------+-----------+-----------+-----------+-----------+
输出：
+-------------+-----------+-------+
| product   | quarter   | sales |
+-------------+-----------+-------+
| Umbrella  | quarter_1 | 417   |
| SleepingBag | quarter_1 | 800   |
| Umbrella  | quarter_2 | 224   |
| SleepingBag | quarter_2 | 936   |
| Umbrella  | quarter_3 | 379   |
| SleepingBag | quarter_3 | 93  |
| Umbrella  | quarter_4 | 611   |
| SleepingBag | quarter_4 | 875   |
+-------------+-----------+-------+
解释：
DataFrame 已从宽格式重塑为长格式。每一行表示一个季度内产品的销售情况。

解法

方法一

import pandas as pd


def meltTable(report: pd.DataFrame) -> pd.DataFrame:
  return pd.melt(report, id_vars=['product'], var_name='quarter', value_name='sales')