I would like to replace the value NaN of day 20211021 - HOUR 1 with the value of day 20211020 - HOUR 1, the value of day day 20211021 - HOUR 2 with the value of day 20211020 - HOUR 2...
| timestamp | data | year | month | day | hour | solar_total |
|---|---|---|---|---|---|---|
| 2021-10-20 00:00:00 | 20211020 | 2021 | 10 | 20 | 1 | 0.0 |
| 2021-10-20 01:00:00 | 20211020 | 2021 | 10 | 20 | 2 | 0.0 |
| 2021-10-20 02:00:00 | 20211020 | 2021 | 10 | 20 | 3 | 0.0 |
| 2021-10-20 03:00:00 | 20211020 | 2021 | 10 | 20 | 4 | 0.0 |
| 2021-10-20 04:00:00 | 20211020 | 2021 | 10 | 20 | 5 | 0.0 |
| 2021-10-20 05:00:00 | 20211020 | 2021 | 10 | 20 | 6 | 0.0 |
| 2021-10-20 06:00:00 | 20211020 | 2021 | 10 | 20 | 7 | 0.0 |
| 2021-10-20 07:00:00 | 20211020 | 2021 | 10 | 20 | 8 | 65.0 |
| 2021-10-20 08:00:00 | 20211020 | 2021 | 10 | 20 | 9 | 1498.0 |
| 2021-10-20 09:00:00 | 20211020 | 2021 | 10 | 20 | 10 | 4034.0 |
| 2021-10-20 10:00:00 | 20211020 | 2021 | 10 | 20 | 11 | 6120.0 |
| 2021-10-20 11:00:00 | 20211020 | 2021 | 10 | 20 | 12 | 7450.0 |
| 2021-10-20 12:00:00 | 20211020 | 2021 | 10 | 20 | 13 | 7943.0 |
| 2021-10-20 13:00:00 | 20211020 | 2021 | 10 | 20 | 14 | 7821.0 |
| 2021-10-20 14:00:00 | 20211020 | 2021 | 10 | 20 | 15 | 7058.0 |
| 2021-10-20 16:00:00 | 20211020 | 2021 | 10 | 20 | 17 | 3664.0 |
| 2021-10-20 17:00:00 | 20211020 | 2021 | 10 | 20 | 18 | 1375.0 |
| 2021-10-20 18:00:00 | 20211020 | 2021 | 10 | 20 | 19 | 11.0 |
| 2021-10-20 19:00:00 | 20211020 | 2021 | 10 | 20 | 20 | 0.0 |
| 2021-10-20 20:00:00 | 20211020 | 2021 | 10 | 20 | 21 | 0.0 |
| 2021-10-20 21:00:00 | 20211020 | 2021 | 10 | 20 | 22 | 0.0 |
| 2021-10-20 22:00:00 | 20211020 | 2021 | 10 | 20 | 23 | 0.0 |
| 2021-10-20 23:00:00 | 20211020 | 2021 | 10 | 20 | 24 | 0.0 |
| 2021-10-21 00:00:00 | 20211021 | 2021 | 10 | 21 | 1 | NaN |
| 2021-10-21 01:00:00 | 20211021 | 2021 | 10 | 21 | 2 | NaN |
| 2021-10-21 02:00:00 | 20211021 | 2021 | 10 | 21 | 3 | NaN |
| 2021-10-21 03:00:00 | 20211021 | 2021 | 10 | 21 | 4 | NaN |
| 2021-10-21 04:00:00 | 20211021 | 2021 | 10 | 21 | 5 | NaN |
| 2021-10-21 05:00:00 | 20211021 | 2021 | 10 | 21 | 6 | NaN |
| 2021-10-21 06:00:00 | 20211021 | 2021 | 10 | 21 | 7 | NaN |
| 2021-10-21 07:00:00 | 20211021 | 2021 | 10 | 21 | 8 | NaN |
| 2021-10-21 08:00:00 | 20211021 | 2021 | 10 | 21 | 9 | NaN |
| 2021-10-21 09:00:00 | 20211021 | 2021 | 10 | 21 | 10 | NaN |
| 2021-10-21 10:00:00 | 20211021 | 2021 | 10 | 21 | 11 | NaN |
| 2021-10-21 11:00:00 | 20211021 | 2021 | 10 | 21 | 12 | NaN |
| 2021-10-21 12:00:00 | 20211021 | 2021 | 10 | 21 | 13 | NaN |
| 2021-10-21 13:00:00 | 20211021 | 2021 | 10 | 21 | 14 | NaN |
| 2021-10-21 14:00:00 | 20211021 | 2021 | 10 | 21 | 15 | NaN |
| 2021-10-21 15:00:00 | 20211021 | 2021 | 10 | 21 | 16 | NaN |
| 2021-10-21 16:00:00 | 20211021 | 2021 | 10 | 21 | 17 | NaN |
| 2021-10-21 17:00:00 | 20211021 | 2021 | 10 | 21 | 18 | NaN |
| 2021-10-21 18:00:00 | 20211021 | 2021 | 10 | 21 | 19 | NaN |
| 2021-10-21 19:00:00 | 20211021 | 2021 | 10 | 21 | 20 | NaN |
| 2021-10-21 20:00:00 | 20211021 | 2021 | 10 | 21 | 21 | NaN |
| 2021-10-21 21:00:00 | 20211021 | 2021 | 10 | 21 | 22 | NaN |
| 2021-10-21 22:00:00 | 20211021 | 2021 | 10 | 21 | 23 | NaN |
| 2021-10-21 23:00:00 | 20211021 | 2021 | 10 | 21 | 24 | NaN |
CodePudding user response：
If you have no missing timestamp, shift your rows by 23:
df['solar_total'] = df['solar_total'].fillna(df['solar_total'].shift(23))
| timestamp | data | year | month | day | hour | solar_total |
|---|---|---|---|---|---|---|
| 2021-10-20 00:00:00 | 20211020 | 2021 | 10 | 20 | 1 | 0 |
| 2021-10-20 01:00:00 | 20211020 | 2021 | 10 | 20 | 2 | 0 |
| 2021-10-20 02:00:00 | 20211020 | 2021 | 10 | 20 | 3 | 0 |
| 2021-10-20 03:00:00 | 20211020 | 2021 | 10 | 20 | 4 | 0 |
| 2021-10-20 04:00:00 | 20211020 | 2021 | 10 | 20 | 5 | 0 |
| 2021-10-20 05:00:00 | 20211020 | 2021 | 10 | 20 | 6 | 0 |
| 2021-10-20 06:00:00 | 20211020 | 2021 | 10 | 20 | 7 | 0 |
| 2021-10-20 07:00:00 | 20211020 | 2021 | 10 | 20 | 8 | 65 |
| 2021-10-20 08:00:00 | 20211020 | 2021 | 10 | 20 | 9 | 1498 |
| 2021-10-20 09:00:00 | 20211020 | 2021 | 10 | 20 | 10 | 4034 |
| 2021-10-20 10:00:00 | 20211020 | 2021 | 10 | 20 | 11 | 6120 |
| 2021-10-20 11:00:00 | 20211020 | 2021 | 10 | 20 | 12 | 7450 |
| 2021-10-20 12:00:00 | 20211020 | 2021 | 10 | 20 | 13 | 7943 |
| 2021-10-20 13:00:00 | 20211020 | 2021 | 10 | 20 | 14 | 7821 |
| 2021-10-20 14:00:00 | 20211020 | 2021 | 10 | 20 | 15 | 7058 |
| 2021-10-20 16:00:00 | 20211020 | 2021 | 10 | 20 | 17 | 3664 |
| 2021-10-20 17:00:00 | 20211020 | 2021 | 10 | 20 | 18 | 1375 |
| 2021-10-20 18:00:00 | 20211020 | 2021 | 10 | 20 | 19 | 11 |
| 2021-10-20 19:00:00 | 20211020 | 2021 | 10 | 20 | 20 | 0 |
| 2021-10-20 20:00:00 | 20211020 | 2021 | 10 | 20 | 21 | 0 |
| 2021-10-20 21:00:00 | 20211020 | 2021 | 10 | 20 | 22 | 0 |
| 2021-10-20 22:00:00 | 20211020 | 2021 | 10 | 20 | 23 | 0 |
| 2021-10-20 23:00:00 | 20211020 | 2021 | 10 | 20 | 24 | 0 |
| 2021-10-21 00:00:00 | 20211021 | 2021 | 10 | 21 | 1 | 0 |
| 2021-10-21 01:00:00 | 20211021 | 2021 | 10 | 21 | 2 | 0 |
| 2021-10-21 02:00:00 | 20211021 | 2021 | 10 | 21 | 3 | 0 |
| 2021-10-21 03:00:00 | 20211021 | 2021 | 10 | 21 | 4 | 0 |
| 2021-10-21 04:00:00 | 20211021 | 2021 | 10 | 21 | 5 | 0 |
| 2021-10-21 05:00:00 | 20211021 | 2021 | 10 | 21 | 6 | 0 |
| 2021-10-21 06:00:00 | 20211021 | 2021 | 10 | 21 | 7 | 0 |
| 2021-10-21 07:00:00 | 20211021 | 2021 | 10 | 21 | 8 | 65 |
| 2021-10-21 08:00:00 | 20211021 | 2021 | 10 | 21 | 9 | 1498 |
| 2021-10-21 09:00:00 | 20211021 | 2021 | 10 | 21 | 10 | 4034 |
| 2021-10-21 10:00:00 | 20211021 | 2021 | 10 | 21 | 11 | 6120 |
| 2021-10-21 11:00:00 | 20211021 | 2021 | 10 | 21 | 12 | 7450 |
| 2021-10-21 12:00:00 | 20211021 | 2021 | 10 | 21 | 13 | 7943 |
| 2021-10-21 13:00:00 | 20211021 | 2021 | 10 | 21 | 14 | 7821 |
| 2021-10-21 14:00:00 | 20211021 | 2021 | 10 | 21 | 15 | 7058 |
| 2021-10-21 15:00:00 | 20211021 | 2021 | 10 | 21 | 16 | 3664 |
| 2021-10-21 16:00:00 | 20211021 | 2021 | 10 | 21 | 17 | 1375 |
| 2021-10-21 17:00:00 | 20211021 | 2021 | 10 | 21 | 18 | 11 |
| 2021-10-21 18:00:00 | 20211021 | 2021 | 10 | 21 | 19 | 0 |
| 2021-10-21 19:00:00 | 20211021 | 2021 | 10 | 21 | 20 | 0 |
| 2021-10-21 20:00:00 | 20211021 | 2021 | 10 | 21 | 21 | 0 |
| 2021-10-21 21:00:00 | 20211021 | 2021 | 10 | 21 | 22 | 0 |
| 2021-10-21 22:00:00 | 20211021 | 2021 | 10 | 21 | 23 | 0 |
| 2021-10-21 23:00:00 | 20211021 | 2021 | 10 | 21 | 24 | nan |