DEPR: Remove pandas.np

[datapythonista]

Not sure if it was added intentionally, but it's possible to call numpy with the np attribute of the pandas module:

import pandas
x = pandas.np.array([1, 2, 3])

While this is not documented, I've seen couple of places suggesting this as a "trick" to avoid importing numpy directly.

I personally find this hacky, and I think should be removed.

[AlexKirko]

There is a chance removing this will break something, in case adding it wasn't random, but I believe it should still be removed. It's ugly and the issues that might arise are easily fixable.
As far as I can see, all this would entail is a one-line edit to __init__.py I found no explanation why np was added in the code or in the API reference.
Edit: I did find a colleague who relied on this, so even if our code doesn't break anything in the library (or if we fix it), this change will still break backward compatibility for some users.

[datapythonista]

We remove everything gradually, by first raising warnings.

I think there are other things we may also want to check if we should remove, I saw a pandas.array that I guess is an alias for numpy.array.

[mroeschke]

Similar but more minor, looks like users will also import datetime.datetime with import pandas which I find odd.

In [1]: import pandas

In [2]: pandas.datetime
Out[2]: datetime.datetime

[AlexKirko]

Fair point about the deprecation warning.

pd.array, however, isn't just an alias. It allows to make arrays of pandas-specific datatypes.

This works:

pd.array([1,2,3], dtype=pd.Int64Dtype())

<IntegerArray>
[1, 2, 3]
Length: 3, dtype: Int64

This doesn't:

np.array([1,2,3], dtype=pd.Int64Dtype())

TypeError                                 Traceback (most recent call last)
<ipython-input-7-6ae38424b9f7> in <module>
----> 1 np.array([1,2,3], dtype=pd.Int64Dtype())

TypeError: data type not understood

[xhochy]

The numpy import is actually explicit:

pandas/pandas/__init__.py

Line 108 in 37dfcc1

np,

but is simply a redirect to normal numpy:

pandas/pandas/core/api.py

Line 3 in 37dfcc1

import numpy as np

Still, I have often met users that swear that pandas.np is different from np as it provides a compatability layer between NumPy and pandas. Removing this alias would also wipe out this myth. As it is just an alias, the breaking change is really easy to resolve.

The datetime import is also

pandas/pandas/__init__.py

Line 42 in 37dfcc1

from datetime import datetime

only there for importing it via pandas.datetime. There is no usage of it in the __init__.py.

[jorisvandenbossche]

For python 3.7+, we can actually deprecate this with the module getattr trick (the same we use for Panel dummy class right now). So I think we can go through a deprecation cycle instead of directly removing (for python 3.6, this is more difficult though).

[datapythonista]

pd.array, however, isn't just an alias.

Yep, I got confused, it's obviously our own array.

[lithomas1]

take