ENH: Utility function to swap all dtypes `numpy` ↔ `pyarrow`

[randolf-scholz]

Feature Type

• Adding new functionality to pandas

• Changing existing functionality in pandas

• Removing existing functionality in pandas

Problem Description

It would be nice to have a utility function that swaps the backend of all dtypes of an existing DataFrame/Series/Index.

Feature Description

One could consider repurposing the DataFrame.convert_dtypes for this functionality.

Currently, it does nothing:

import numpy as np
import pandas as pd
import pyarrow as pa

s_arrow = pd.Series(np.arange(100), dtype="int32[pyarrow]")
s_numpy = pd.Series(np.arange(100), dtype="Int32")

s = s_arrow.convert_dtypes(dtype_backend="numpy_nullable")
assert s_numpy.dtype == s.dtype  # ✘ AssertionError

Alternative Solutions

Potentially, one could also allow passing a transformation schema dict[input_type, output_type] to the astype function.

Additional Context

No response