| Serial Number | Age | Characteristics |
|---|---|---|
| 1001 | 20 | Tall |
| 1002 | 23 | Blue |
| 1001 | 20 | Black |
| 1002 | 23 | Short |
| 1003 | 19 | Green |
Desired output:
| Serial Number | Age | Characteristics |
|---|---|---|
| 1001 | 20 | Tall,Black |
| 1002 | 23 | Short,Blue |
| 1003 | 19 | Green |
You should first use groupby then in agg use ','.join like this
df.groupby("Serial Number").agg({"Age": "last", "Characteristics": ','.join})