How to Keep Only the First Record When Times Differ by Less Than 20 Seconds in Python

1. Introduction

Hello, I am PiPi. In a Python community I was asked to solve a practical automation problem: given a table with columns 编号, 环节, 审核人, 金额, and 结束时间, group by the first four columns, sort each group by 结束时间 ascending, and keep only the first record when the time difference between consecutive rows is within 20 seconds.

2. Implementation

A user raised a follow‑up question about a case where a group contains three timestamps (2023‑11‑27 15:50:00, 15:50:05, 15:50:25). The expected output should keep the first and third timestamps, ensuring any two timestamps in the same group differ by more than 20 seconds.

To demonstrate, three additional rows were added to the sample data. The processing script was run, and the resulting output showed 3,395 rows, one more than the original 3,394 rows, confirming the logic works for the edge case.

Result comparison screenshots:

The original result contained 3,394 rows.

After the adjustment, the output correctly handled the special case.

3. Conclusion

This article presented a real‑world Python automation problem, explained the grouping and time‑difference logic, and provided a working implementation that successfully resolved the issue.

Thanks to the community members who contributed ideas and feedback. A reminder: when posting large datasets, anonymize sensitive data, include a minimal reproducible example, and attach error screenshots. For extensive code, share a .py file.