pandas pyarrow-backed strings display differently to other strings

[MarcoGorelli]

Prework

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Description

if I run

from great_tables import GT
import pandas as pd

df = pd.DataFrame(
    {
        "example": ["Row " + str(x) for x in range(1, 5)],
        "numbers": [
            "20 23 6 7 37 23 21 4 7 16",
            "2.3 6.8 9.2 2.42 3.5 12.1 5.3 3.6 7.2 3.74",
            "-12 -5 6 3.7 0 8 -7.4",
            "2 0 15 7 8 10 1 24 17 13 6",i
        ],
    }
)
GT(df)

and then

GT(df.convert_dtypes(dtype_backend='pyarrow'))

then they display differently

For Polars, the alignment is different still?

Reproducible example

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Expected result

I think they should look the same?

Development environment

• Operating System: linux
• great_tables Version: 0.11.0

Additional context

Add any other context about the problem here.

[machow]

Shoot -- this issue comes from our very old and rough code for handling alignment:

great-tables/great_tables/_gt_data.py

Line 308 in 079dc83

def align_from_data(self, data: TblData):

Currently, it uses the string names of dtypes, which is a bit brittle (def an area where narwhals can help ;). We should move this code into out DataFrame backend layer, _tbl_data.py, and clean up the detection of dtypes.