SparseArray not in arrays module - inconsistent with IntegerArray, StringArray, etc.

[Dr-Irv]

Code Sample, a copy-pastable example if possible

In [1]: import pandas as pd

In [2]: pd.__version__
Out[2]: '0.26.0.dev0+1563.g1feefc692'

In [3]: pd.SparseArray
Out[3]: pandas.core.arrays.sparse.array.SparseArray

In [4]: pd.arrays.SparseArray
Out[4]: pandas.core.arrays.sparse.array.SparseArray

In [5]: pd.arrays.IntegerArray
Out[5]: pandas.core.arrays.integer.IntegerArray

In [6]: pd.IntegerArray
---------------------------------------------------------------------------
AttributeError                            Traceback (most recent call last)
<ipython-input-6-12476104dd13> in <module>
----> 1 pd.IntegerArray

C:\Code\pandas_dev\pandas\pandas\__init__.py in __getattr__(name)
    246             return type(name, (), {})
    247
--> 248         raise AttributeError(f"module 'pandas' has no attribute '{name}'")
    249
    250

AttributeError: module 'pandas' has no attribute 'IntegerArray'

In [7]: pd.arrays.StringArray
Out[7]: pandas.core.arrays.string_.StringArray

In [8]: pd.StringArray
---------------------------------------------------------------------------
AttributeError                            Traceback (most recent call last)
<ipython-input-8-86553ff3c48c> in <module>
----> 1 pd.StringArray

C:\Code\pandas_dev\pandas\pandas\__init__.py in __getattr__(name)
    246             return type(name, (), {})
    247
--> 248         raise AttributeError(f"module 'pandas' has no attribute '{name}'")
    249
    250

AttributeError: module 'pandas' has no attribute 'StringArray'

Problem description

I discovered this while working on #30628 . The docs for SparseArray are at the top level (https://dev.pandas.io/docs/reference/api/pandas.SparseArray.html), while the docs for IntegerArray (https://dev.pandas.io/docs/reference/api/pandas.arrays.IntegerArray.html), StringArray(https://dev.pandas.io/docs/reference/api/pandas.arrays.StringArray.html), etc. are at the pandas.arrays level.

In the code SparseArray is at both levels, but IntegerArray, StringArray, etc. is only at the arrays level.

Expected Output

Unsure.

It seems that this should be consistent. Options are:

1. Put all *Array classes at top level, and document them that way. (i.e., use the pattern currently used for SparseArray). That would involve code and documentation changes for all of the arrays except SparseArray.
2. Put all *Array classes at both levels (like SparseArray), but document them at the pandas.arrays level (like IntegerArray and StringArray). That would involve code changes for all of the arrays, and doc changes for SparseArray.
3. Put all *Array classes only at the pandas.arrays level and document them all that way. That would involve only changing code and docs for SparseArray and leaving the others alone.

It's not clear to me which is preferred.

Output of pd.show_versions()

INSTALLED VERSIONS

commit : 1feefc6
python : 3.7.3.final.0
python-bits : 64
OS : Windows
OS-release : 10
machine : AMD64
processor : Intel64 Family 6 Model 158 Stepping 13, GenuineIntel
byteorder : little
LC_ALL : None
LANG : None
LOCALE : None.None

pandas : 0.26.0.dev0+1563.g1feefc692
numpy : 1.17.4
pytz : 2019.3
dateutil : 2.8.1
pip : 19.3.1
setuptools : 42.0.2.post20191203
Cython : 0.29.14
pytest : 5.3.2
hypothesis : 4.54.2
sphinx : 2.3.0
blosc : None
feather : None
xlsxwriter : 1.2.6
lxml.etree : 4.4.2
html5lib : 1.0.1
pymysql : None
psycopg2 : None
jinja2 : 2.10.3
IPython : 7.10.2
pandas_datareader: None
bs4 : 4.8.1
bottleneck : 1.3.1
fastparquet : None
gcsfs : None
lxml.etree : 4.4.2
matplotlib : 3.1.1
numexpr : 2.7.0
odfpy : None
openpyxl : 3.0.2
pandas_gbq : None
pyarrow : None
pytables : None
pytest : 5.3.2
s3fs : None
scipy : 1.3.2
sqlalchemy : 1.3.11
tables : 3.6.1
tabulate : None
xarray : None
xlrd : 1.2.0
xlwt : 1.3.0
xlsxwriter : 1.2.6
numba : 0.46.0

[jreback]

Sparse is incorrect and somewhat legacy

all things should be at pandas.array level to avoid polluting the main namespace

so need to deprecate from the main namespace
i thought we had an issue about this

[Dr-Irv]

@jreback I searched for an issue and couldn't find it. So if we deprecate now, does that mean we

A. keep pandas.SparseArray, and just fix the docs to point to pandas.arrays.SparseArray,
B. remove pandas.SparseArray now (i.e., option 3 above)

I'm willing to do this once #30628 is merged to master (should be green pretty soon)

[jreback]

@jreback I searched for an issue and couldn't find it. So if we deprecate now, does that mean we

A. keep pandas.SparseArray, and just fix the docs to point to pandas.arrays.SparseArray,
B. remove pandas.SparseArray now (i.e., option 3 above)

I'm willing to do this once #30628 is merged to master (should be green pretty soon)

deprecate pd.SparseArray, fix all docs to point to pandas.array.SparseArray

[jorisvandenbossche]

Reopening to track my comment in the PR: #30656 (comment) (so we have an issue with the correct milestone)

[TomAugspurger]

Do we need to revert #30656 until the deprecation for Py37 and earlier is fixed?

[Dr-Irv]

Do we need to revert #30656 until the deprecation for Py37 and earlier is fixed?

@TomAugspurger I should have a fix within a few hours.

[TomAugspurger]

Great, thanks!

…

On Tue, Jan 7, 2020 at 9:10 AM Irv Lustig ***@***.***> wrote: Do we need to revert #30656 <#30656> until the deprecation for Py37 and earlier is fixed? @TomAugspurger <https://github.com/TomAugspurger> I should have a fix within a few hours. — You are receiving this because you were mentioned. Reply to this email directly, view it on GitHub <#30642?email_source=notifications&email_token=AAKAOIUCUQ7JWYSOT7W5C5LQ4SLO7A5CNFSM4KCM2ET2YY3PNVWWK3TUL52HS4DFVREXG43VMVBW63LNMVXHJKTDN5WW2ZLOORPWSZGOEIJFO2I#issuecomment-571627369>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AAKAOIVSZFHRWANOGIYHG2LQ4SLO7ANCNFSM4KCM2ETQ> .