# ds1000 / 260

- taskset: [ds1000](https://harnessreport.com/tasks/ds1000.md)
- difficulty: 
- category: 
- language: 
- runnable from the site: no
- agent timeout: 1800s

## Results by harness

_none yet_

## Instruction

```
# 260: DS-1000 Task

## Prompt
Problem:
i got an issue over ranking of date times. Lets say i have following table.
ID    TIME
01    2018-07-11 11:12:20
01    2018-07-12 12:00:23
01    2018-07-13 12:00:00
02    2019-09-11 11:00:00
02    2019-09-12 12:00:00


and i want to add another column to rank the table by time for each id and group. I used 
df['RANK'] = data.groupby('ID')['TIME'].rank(ascending=False)


but get an error:
'NoneType' object is not callable


If i replace datetime to numbers, it works.... any solutions?


A:
<code>
import pandas as pd


df = pd.DataFrame({'ID': ['01', '01', '01', '02', '02'],
                   'TIME': ['2018-07-11 11:12:20', '2018-07-12 12:00:23', '2018-07-13 12:00:00', '2019-09-11 11:00:00', '2019-09-12 12:00:00']})
</code>
df = ... # put solution in this variable
BEGIN SOLUTION
<code>

## What to do
- Edit `solution/solution.py` so the code passes the DS-1000 tests.
- Do not access the internet or install new packages; required libraries are preinstalled in the Docker image.
- Run tests locally via `bash tests/test.sh`.

## Notes
- Keep the variable names/signatures implied by the prompt/code_context.
- The evaluator uses the original DS-1000 `code_context` (`test_execution` / `test_string`).
```
---
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