I have following dataframe,
| ID | d_of_stay |
|---|---|
| 1 | 2021-03-01 |
| 1 | 2021-03-02 |
| 1 | 2021-03-03 |
| 2 | 2021-03-05 |
| 2 | 2021-03-06 |
I have to create a column like below,
| ID | d_of_stay | day |
|---|---|---|
| 1 | 2021-03-01 | Day 0 |
| 1 | 2021-03-02 | Day 1 |
| 1 | 2021-03-03 | Day 2 |
| 2 | 2021-03-05 | Day 0 |
| 2 | 2021-03-06 | Day 1 |
How to do that using pandas/python?
>Solution :
This will give you the results you expect IIUC
df['day'] = df.groupby('ID')['d_of_stay'].cumcount()
df['day'] = 'Day ' + df['day'].astype(str)