Series[Sparse].to_dense not converting to dense.

[TomAugspurger]

In [1]: import pandas as pd

In [2]: s = pd.Series([1, 2], dtype='Sparse[int]')

In [3]: s.to_dense()
Out[3]:
0    1
1    2
dtype: Sparse[int64, 0]

[TomAugspurger]

So, I think we can (deprecate) and remove to_dense from NDFrame.

Then we recommend the.sparse.to_dense method on the accessor (I'm working on a DataFrame accessor now for the SparseDataFrame deprecations).

[jorisvandenbossche]

+1 for that proposal (I suppose the historical reason was for compat with the method on SparseSeries ?)

[TomAugspurger]

More likely, I just didn't understand what this function was doing :) But yes, pre-SparseArray is an extension array, `concat([Series[sparse]])` would return a SparseSeries rather than a Series with sparse values. Edit: whoops wrong issue. Not sure what the original reason was.

[jorisvandenbossche]

Closing this in favor of #26557