Document DataFrame._constructor_sliced-like property in the public API?

[TomAugspurger]

Can we document something like DataFrame._constructor_sliced as the public way to say that slicing a column from a pandas.DataFrame will return a pandas.Series object?

Projects like Dask would like to work with any concrete DataFrame library (cudf being the second major dataframe implementation). Right now we resort to things like type(dask.dataframe.DataFrame._meta.iloc[:, 0]) to get the concrete type of a slice. But that's fragile (e.g. a DataFrame with no columns).

I'm not sure how useful this would be to users, so using an underscore-prefixed name may be reasonable.

[TomAugspurger]

cc @rjzamora @kkraus14

[jorisvandenbossche]

Can we document something like DataFrame._constructor_sliced as the public way to say that slicing a column from a pandas.DataFrame will return a pandas.Series object?

That is already the case? -> https://pandas.pydata.org/pandas-docs/stable/development/extending.html#override-constructor-properties
(although mentioned specifically in the context of subclasses, not "duck frames")

For me, the main question for that property is if it is required to be a type (class object), or only a "constructor".
Because I was actually looking into changing this for GeoPandas: geopandas/geopandas#1085

[TomAugspurger]

Thanks, I forgot about that doc page.

For dask specifically, we're looking for a type. That name certainly implies a constructor function, which may not be a type. So maybe we should have a new name dedicated to this?

Edit: I'll actually need to take a closer look at how dask is wanting to use this. We may be ok with any callable that returns the series type.