BUG-24915 fix unhashble Series.name in df aggregation

[lofoyet]

• closes Cannot do agg if dataframe has column "name" #24915
• tests added / passed
• passes git diff upstream/master -u -- "*.py" | flake8 --diff
• whatsnew entry

Before creating a pd.Series and pass {name} as argument, check if {name} is hashable. If not use default None.

[lofoyet]

@YaoquanYe @daisysu0310

[lofoyet]

1. not sure about what tests to add

[lofoyet]

@youhealthy and I are the same person

[codecov]

Codecov Report

Merging #24920 into master will increase coverage by <.01%.
The diff coverage is 100%.

@@ Coverage Diff @@ ## master #24920 +/- ## ========================================== + Coverage 92.38% 92.38% +<.01%  ========================================== Files 166 166 Lines 52404 52406 +2 ========================================== + Hits 48412 48414 +2  Misses 3992 3992

Flag	Coverage Δ
#multiple	90.8% <100%> (ø)	⬆️
#single	42.9% <0%> (-0.01%)	⬇️

Impacted Files	Coverage Δ
pandas/core/base.py	97.76% <100%> (+0.01%)	⬆️

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 539c54f...b270371. Read the comment docs.

[codecov]

Codecov Report

Merging #24920 into master will increase coverage by <.01%.
The diff coverage is 100%.

@@ Coverage Diff @@ ## master #24920 +/- ## ========================================== + Coverage 92.38% 92.38% +<.01%  ========================================== Files 166 166 Lines 52404 52406 +2 ========================================== + Hits 48412 48414 +2  Misses 3992 3992

Flag	Coverage Δ
#multiple	90.8% <100%> (ø)	⬆️
#single	42.9% <0%> (-0.01%)	⬇️

Impacted Files	Coverage Δ
pandas/core/base.py	97.76% <100%> (+0.01%)	⬆️

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 539c54f...b270371. Read the comment docs.

[mroeschke]

Needs:

• Whatsnew entry for 0.24.1
• Test: Add a test based on the example in the original issue. Construct the DataFrame/Series that replicates the issue and the expected DataFrame/Series

[jreback]

this needs a test. I am also not sure this is actually the correct fix. constructio of a Series from scalars with an invalid name with raise now. IOW this should be raising already, so not sure this is a good remedy.

`

In [1]: Series([1,2],name=[1,2]) --------------------------------------------------------------------------- TypeError Traceback (most recent call last) <ipython-input-1-360525e04c11> in <module> ----> 1 Series([1,2],name=[1,2]) ~/pandas/pandas/core/series.py in __init__(self, data, index, dtype, name, copy, fastpath) 266 generic.NDFrame.__init__(self, data, fastpath=True) 267 --> 268 self.name = name 269 self._set_axis(0, index, fastpath=True) 270 ~/pandas/pandas/core/generic.py in __setattr__(self, name, value) 5077 object.__setattr__(self, name, value) 5078 elif name in self._metadata: -> 5079 object.__setattr__(self, name, value) 5080 else: 5081 try: ~/pandas/pandas/core/series.py in name(self, value) 400 def name(self, value): 401 if value is not None and not is_hashable(value): --> 402 raise TypeError('Series.name must be a hashable type') 403 object.__setattr__(self, '_name', value) 404 TypeError: Series.name must be a hashable type 

[lofoyet]

@jreback I agree with you. You can refer to #24915 for the problem.

There are 2 ways that I have in mind to fix this:

1. This PR.
2. Make change to how getattr works.

For 2. What I looked at is

#pandas.core.generic.py if (name in self._internal_names_set or name in self._metadata or name in self._accessors): return object.__getattribute__(self, name) else: if self._info_axis._can_hold_identifiers_and_holds_name(name): return self[name] return object.__getattribute__(self, name)

getattr(self, "name") will go to else clause, and if "name" is a column, it will return in if clause. But df.name is really an attribute rather not a column name. It should skip that "if" in "else" and goes to object.getattribute().

How do you propose to change? @jreback

[lofoyet]

@jreback any idea?

[jreback]

@lofoyet first thing you need here is a test. Then step thru it until you get to the source of the error, see if you patch fixes.

I would rather shy away from changing the way getattr works. Also I am not sure your change is the right way.

[WillAyd]

Closing as stale. @lofoyet ping if you'd like to continue though as mentioned above this needs a test first and foremost