How to Aggregate and Concatenate Columns in Pandas: A Practical Guide

Introduction

Hello, I am PiPi. A few days ago, a member of the Python elite group asked a Pandas data‑processing question. The original query screenshot is shown below.

The expected result is illustrated in the following image.

Implementation Process

The problem initially looks confusing and requires several readings. A workable solution was provided:

df.groupby(by=["song_name","actor_name"], sort=False)[["tblTags","song_id"]].sum()

However, the song_id column cannot specify a delimiter, so commas must be added manually.

A simpler approach is to add commas during aggregation and then strip trailing commas:

df.groupby(["song_name", "actor_name"]).agg({
    "song_id": lambda x: ",".join(x),
    "tblTags": sum
})

This method successfully resolved the issue for the user.

Conclusion

The article presented a specific Pandas data‑processing challenge, explained the problem, and offered concrete code solutions that helped the community solve it.

Thanks to the contributors who provided the ideas and code snippets.