What happened:

I tried to pass columns from a Dask DataFrame into regression metrics like mean_squared_error(), and this raised errors like

AttributeError: 'Scalar' object has no attribute 'mean'

What you expected to happen:

I expected that I'd be able to pass a column from a Dask DataFrame (which has type dask.dataframe.core.Series) into any of the metrics functions.

Minimal Complete Verifiable Example:

import dask
import dask.dataframe as dd
from dask.distributed import Client, LocalCluster

cluster = LocalCluster()
client = Client(cluster)
cluster

ddf = dask.datasets.timeseries()

from dask_ml.metrics import mean_squared_error

mean_squared_error(
    y_true=ddf["y"],
    y_pred=ddf["y"]
)

Anything else we need to know?:

I looked around and couldn't find documentation that would lead me to think this wouldn't work, or other issues that seemed related.

Environment:

• Dask version (output of pip freeze | grep -E "dask|distributed")

  • dask==2.30.0
    dask-cloudprovider==0.4.1
    dask-glm==0.2.0
    dask-ml==1.7.0
    distributed==2.30.1

• Python version: 3.8.3.final.0
• Operating System: macOS 10.14.6
• Install method (conda, pip, source): pip

Thanks for your time and consideration