DataFrame.head shouldn't warn when there's one partition #8088
Description
dask.data
In [12]: import dask.dataframe as dd, pandas as pd
In [13]: df = dd.from_pandas(pd.DataFrame({"A": [1, 2]}), npartitions=1)
In [14]: df.head()
/home/taugspurger/miniconda3/envs/stac-table/lib/python3.9/site-packages/dask/dataframe/core.py:6778: UserWarning: Insufficient elements for `head`. 5 elements requested, only 2 elements available. Try passing larger `npartitions` to `head`.
warnings.warn(msg.format(n, len(r)))
Out[14]:
A
0 1
1 2When there's just a single partition (or, more generally, if all the partitions are used), then there's no reason to warn.
I think the fix is change
Lines 1081 to 1084 in 7cfee4a
Line 1071 in 7cfee4a
safe=False when npartitions == self.npartitions (or when npartitions=-1).