Complete NumPy ufunc compatibility in Series

[HyukjinKwon]

This PR completes NumPy's ufunc support (followup of #1096).

See also https://docs.scipy.org/doc/numpy/reference/arrays.classes.html#standard-array-subclasses

E.g.:

>>> import databricks.koalas as ks
>>> import numpy as np
>>> kdf = ks.range(10)
>>> kser = np.sqrt(kdf.id)
>>> type(kser)
<class 'databricks.koalas.series.Series'>
>>> kser
0    0.000000
1    1.000000
2    1.414214
3    1.732051
4    2.000000
5    2.236068
6    2.449490
7    2.645751
8    2.828427
9    3.000000

[codecov-io]

Codecov Report

Merging #1106 into master will increase coverage by 0.01%.
The diff coverage is 91.17%.

@@            Coverage Diff             @@
##           master    #1106      +/-   ##
==========================================
+ Coverage   95.19%   95.21%   +0.01%     
==========================================
  Files          34       35       +1     
  Lines        6935     6953      +18     
==========================================
+ Hits         6602     6620      +18     
  Misses        333      333

Impacted Files	Coverage Δ
databricks/koalas/base.py	96.05% <100%> (+1.17%)	⬆️
databricks/koalas/numpy_compat.py	90% <90%> (ø)

---

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 ad946fb...b59e233. Read the comment docs.

[softagram-bot]

Softagram Impact Report for pull/1106 (head commit: b59e233)

⚠️ Copy paste found

ℹ️ test_numpy_compat.py: Copy paste fragment on line 24 shared with ../test_dataframe.py:

    @property
    def pdf(self):
        return pd.DataFrame({
            'a': [1, 2, 3, 4, 5, 6, 7, 8, 9],
            'b': [4, 5, 6, 3, 2, 1, ...(truncated 160 chars)

ℹ️ test_numpy_compat.py: Copy paste fragment on line 24 shared with ../test_dataframe.py, ../test_indexes.py:

    @property
    def pdf(self):
        return pd.DataFrame({
            'a': [1, 2, 3, 4, 5, 6, 7, 8, 9],
            'b': [4, 5, 6, 3, 2, 1, ...(truncated 160 chars)

ℹ️ test_numpy_compat.py: Copy paste fragment on line 27 shared with ../test_dataframe.py, ../test_indexes.py, ../test_ops_on_diff_frames.py:

        return pd.DataFrame({
            'a': [1, 2, 3, 4, 5, 6, 7, 8, 9],
            'b': [4, 5, 6, 3, 2, 1, 0, 0, 0],
        }, index=[0, 1, 3, 5, 6, 8, 9, 9, 9])

    @propert...(truncated 20 chars)

Now that you are on the file, it would be easier to pay back some tech. debt.

⭐ Change Overview

(Open in Softagram Desktop for full details)

📄 Full report

• Permalink: Full report for pull/1106

Impact Report explained. Give feedback on this report to [email protected]

[HyukjinKwon]

tests passed.

[HyukjinKwon]

Btw, I ran it few hundreds times and it seems not flaky.

[ueshin]

LGTM.

[ueshin]

Thanks! merging.