DEP: remove deprecated loffset and base args for resample and Grouper
State: closed

- [x] resolves on of the issues listed in #48855
- [x] All [code checks passed](https://pandas.pydata.org/pandas-docs/dev/development/contributing_codebase.html#pre-commit).
- [x]  Added an entry in the latest doc/source/whatsnew/vX.X.X.rst file if fixing a bug or adding a new feature.


This is to enforce deprecation for `loffset` and `base` args which were deprecated in 1.1 (https://github.com/pandas-dev/pandas/pull/31809). 

removing loffset also resolves the pylint issue in #48855

---
Earlier Analysis:

There are two error raised by this check. Both in `Resampler._apply_loffset` for `self.loffset` . 

`loffset` is an attribute of `Grouper` . 

When `.resample` is called like below. A `Resampler` object is returned on a `Grouper` object rather than the `Series` (happens in get_resampler). Therefore, `loffset` attribute defined before access. 

```python
index = pd.date_range('1/1/2000', periods=9, freq='T')
series = pd.Series(range(9), index=index)
s = series.resample('3T')
```

https://github.com/pandas-dev/pandas/blob/75d91c850bd42ffbd8707065b7d3691b7a0cef99/pandas/core/resample.py#L1577-L1585


Labels:
name: Deprecate
description: Functionality to remove in pandas
name: Code Style
description: Code style, linting, code_checks

Comments:
thanks for your PR

looks like loffset is deprecated anyway https://github.com/pandas-dev/pandas/pull/31809/files

Do you want to just enforce the deprecation, so there's no need to ignore the check? There's a bunch of examples of how to do this, e.g. https://github.com/pandas-dev/pandas/pull/49084
sure, it makes sense to enforce deprecation. i will go through the example and update. 
Hi @MarcoGorelli, 

 looks like both `base` and `loffset` args were deprecated at the same time (https://github.com/pandas-dev/pandas/pull/31809)
should I go ahead and look into enforcing deprecation for `base` as well?
yeah, sure
not sure why flake8 is failing. I am unable to reproduce it on local

https://github.com/pandas-dev/pandas/actions/runs/3284846670/jobs/5411280291#step:4:68
Hi @MarcoGorelli , can you please take a look. I have made the changes to remove both `loffset` and `base` args.
I am unable to understand why flake8 is failing. 
```
 flake8..................................................................................................Failed
- hook id: flake8
- exit code: 1

pandas/tests/resample/test_deprecated.py:2:1: F401 'pandas.date_range' imported but unused
```

looks like `date_range` is just unused in that file, you just need to remove it from the imports
> ```
>  flake8..................................................................................................Failed
> - hook id: flake8
> - exit code: 1
> 
> pandas/tests/resample/test_deprecated.py:2:1: F401 'pandas.date_range' imported but unused
> ```
> 
> looks like `date_range` is just unused in that file, you just need to remove it from the imports

it is used in one test here - 

```shell
 pandas/tests/resample/test_deprecated.py ⨯                                                                                                                100% ██████████
---------------------------------------------------------- generated xml file: /workspaces/pandas/test-data.xml ----------------------------------------------------------
========================================================================== slowest 30 durations ==========================================================================
4.49s call     pandas/tests/resample/test_deprecated.py::test_interpolate_posargs_deprecation
0.03s setup    pandas/tests/resample/test_deprecated.py::test_interpolate_posargs_deprecation

(4 durations < 0.005s hidden.  Use -vv to show these durations.)
======================================================================== short test summary info =========================================================================
FAILED pandas/tests/resample/test_deprecated.py::test_pad_backfill_deprecation - NameError: name 'date_range' is not defined

Results (4.96s):
       1 passed
       1 failed
         - pandas/tests/resample/test_deprecated.py:35 test_pad_backfill_deprecation
```

I have installed pre-commit in the dev container on WSL. The commit is not rejected there. 
I checked the version of flake8 installed, and it was also correct. Not able to replicate why it thinks date_range is not used.
I think you just need to fetch upstream and then merge or rebase `upstream/main`, as the function where `date_range` is used has been removed

It's a good practice to reguarly fetch upstream and then merge or rebase 
Thank you. I was looking at only the diff in this PR. 
great. got to know this, my understanding was wrong on the diff- 

>This is a result of the type of diff we use on GitHub. We use git’s three dot diff, which is the difference between the latest commit on the HEAD branch and the last common ancestor commit with the base branch.

@MarcoGorelli Please review now. 
Hi @MarcoGorelli , could you please review this.