Coding questions · Amazon
Identify Date with Highest Total kWh Consumption Using Pandas
This question evaluates proficiency in pandas-based data manipulation and time-series aggregation, specifically the competency to aggregate and summarize meter readings to identify peak consumption dates.
meter_readings
+----------+------------+---------------+---------+
| meter_id | timestamp | kwh_consumed | city |
+----------+------------+---------------+---------+
| 1001 | 2023-01-01 | 15.2 | Austin |
| 1001 | 2023-01-02 | 18.0 | Austin |
| 1002 | 2023-01-01 | 22.5 | Dallas |
| 1002 | 2023-01-02 | 20.1 | Dallas |
| 1003 | 2023-01-01 | 10.7 | Houston |
+----------+------------+---------------+---------+
Scenario
Analyst needs to summarize smart-meter readings for an operations report.
Question
Using pandas, aggregate total kwh_consumed for each date and return the date with the highest total consumption.
Hints
groupby on timestamp, sum, use idxmax or sort_values.
Find date with highest total kWh consumption
Given the meter_readings table of smart-meter data, write an SQL query to aggregate the total kwh_consumed for each date (timestamp) across all meters, and return the single date with the highest total consumption along with that total.
Table meter_readings
| column | type | constraints |
|---|---|---|
| meter_id | INTEGER | |
| timestamp | DATE | |
| kwh_consumed | DECIMAL(10,1) | |
| city | VARCHAR(50) |
Sample data:
| city | kwh_consumed | meter_id | timestamp |
|---|---|---|---|
| Austin | 15.2 | 1001 | 2023-01-01 |
| Austin | 18 | 1001 | 2023-01-02 |
| Dallas | 22.5 | 1002 | 2023-01-01 |
| Dallas | 20.1 | 1002 | 2023-01-02 |
| Houston | 10.7 | 1003 | 2023-01-01 |
Expected output
A single row containing the date (timestamp) with the highest summed kWh across all meters and the corresponding total kWh consumed on that date.
| timestamp | total_kwh_consumed |
|---|---|
| 2023-01-01 | 48.4 |
Hints
- GROUP BY timestamp and SUM kwh_consumed
- ORDER BY the summed value in descending order and LIMIT 1