Math features migrate to numpy

[olikra]

I migrated the transform method in math_features from pandas.agg to native numpy functions with backward compatibility. At least all existing tests on math-feature pass.

Following key-functions are implemented:

• "sum", "np.sum"
• "mean", "np.mean"
• "min", "np.min"
• "max", "np.max"
• "prod", "np.prod"
• "median", "np.median"
• "std", "np.std"
• "var", "np.var"

In case a defined function is not in above collection it falls back to pandas.agg. In the Examples-section I described the way to call a custom function with numpy.apply_over_axes()

I additionally changed the deprecated

dob_datrange = pd.date_range("2020-02-24", periods=4, freq="T")

to

dob_datrange = pd.date_range("2020-02-24", periods=4, freq="min")

to avoid FutureWarnings from pandas.

Please have a look. @solegalli

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 98.50746% with 1 line in your changes missing coverage. Please review.

Project coverage is 97.53%. Comparing base (8cfab26) to head (63f26c9).

Files	Patch %	Lines
feature_engine/creation/math_features.py	98.41%	0 Missing and 1 partial :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #774 +/- ## ========================================== + Coverage 97.52% 97.53% +0.01% ========================================== Files 107 108 +1 Lines 4283 4341 +58 Branches 854 866 +12 ========================================== + Hits 4177 4234 +57 Misses 62 62 - Partials 44 45 +1 ```

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