fix: DataFrameTreeReduction is no longer part of dask

[lgray]

This class was removed from dask itself, and dask-awkward is presently broken with latest dask because of that.

[lgray]

@douglasdavis @martindurant now that the legacy dask dataframe is no longer there, this causes a bunch of tests to fail as well, and forces dependency on dask-expr.

[martindurant]

Is the following enough for those failures:

from dask.dataframe.core import DataFrame
-> 
from dask.dataframe import DataFrame

?

[ikrommyd]

Is the following enough for those failures:

from dask.dataframe.core import DataFrame
-> 
from dask.dataframe import DataFrame

?

It should be. This import was removed recently and works fine for me locally

Python 3.12.7 | packaged by conda-forge | (main, Oct  4 2024, 15:57:01) [Clang 17.0.6 ] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> from dask.dataframe.core import DataFrame
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
ImportError: cannot import name 'DataFrame' from 'dask.dataframe.core' (/Users/iason/miniforge3/envs/egamma-dev/lib/python3.12/site-packages/dask/dataframe/core.py)
>>> from dask.dataframe import DataFrame
>>> exit()

However, please make sure that from dask.dataframe import DataFrame is compatible with older versions of dask/distributed. We typically run on clusters that don't have the latest versions available.

[martindurant]

However, please make sure that from dask.dataframe import DataFrame is compatible with older versions of dask/distributed.

Yes, it has been this way a long time.

[martindurant]

from dask.dataframe import DataFrame

On further reading, this is no longer the same DataFrame as before at all ("DataFrame-like Expr Collection."). There is still a function, dask.dataframe.from_graph that supports making a thing, that might be what we need. What a mess!

(I guess akimbo.dask is broken too)

[martindurant]

@lgray , let me know when you are working on this. I suppose dask-histogram is broken too; but the copy of tree-reduction should live here, so I'll wait for this PR and then fix the other.