make_classification_df date functionality has single repeated value

[ScottMGustafson]

What happened:
When running dask_ml.datasets.make_classification_df with a date range, the generated date column only has a single value, duplicated to length chunks (not n_samples as expected)

This seems to all be related to this line here where it creates an array of length len(X_df) from a single value generated by datasets.random_date

What you expected to happen:
we should be seeing

• many randomly selected dates from within the date range dates
• the date column should be of length n_samples, not chunks

Minimal Complete Verifiable Example:

from dask_ml.datasets import make_classification_df
from datetime import date

X, y = make_classification_df(
    n_samples=100,
    n_features=5,
    random_state=123,
    chunks=10,
    dates=(date(2020, 1, 1), date(2021, 1, 1)),
)

X["date"].compute().value_counts()

returns

2020-02-27    10
Name: date, dtype: int64

Anything else we need to know?:

Environment:

• Dask version: 2021.7.1
• Python version: 3.9.6
• Operating System: linux (ubuntu)
• Install method (conda, pip, source): pip