Implements idxmax()/idxmin() for DataFrame

[itholic]

Resolves #1043

>>> kdf = ks.DataFrame({'a': [1, 2, 3, 2],
...                     'b': [4.0, 2.0, 3.0, 1.0],
...                     'c': [300, 200, 400, 200]})
>>> kdf
   a    b    c
0  1  4.0  300
1  2  2.0  200
2  3  3.0  400
3  2  1.0  200

>>> kdf.idxmax()
a    2
b    0
c    2
Name: 0, dtype: int64

For Multi-column Index

>>> kdf = ks.DataFrame({'a': [1, 2, 3, 2],
...                     'b': [4.0, 2.0, 3.0, 1.0],
...                     'c': [300, 200, 400, 200]})
>>> kdf.columns = pd.MultiIndex.from_tuples([('a', 'x'), ('b', 'y'), ('c', 'z')])
>>> kdf
   a    b    c
   x    y    z
0  1  4.0  300
1  2  2.0  200
2  3  3.0  400
3  2  1.0  200

>>> kdf.idxmax()
(a, x)    2
(b, y)    0
(c, z)    2
Name: 0, dtype: int64

[codecov-io]

Codecov Report

Merging #1054 into master will decrease coverage by 0.06%.
The diff coverage is 96.87%.

@@            Coverage Diff             @@
##           master    #1054      +/-   ##
==========================================
- Coverage    95.2%   95.14%   -0.07%     
==========================================
  Files          34       35       +1     
  Lines        6889     7003     +114     
==========================================
+ Hits         6559     6663     +104     
- Misses        330      340      +10

Impacted Files	Coverage Δ
databricks/koalas/missing/frame.py	100% <ø> (ø)	⬆️
databricks/koalas/frame.py	96.8% <96.87%> (+0.05%)	⬆️
databricks/koalas/utils.py	95.7% <0%> (-2.47%)	⬇️
databricks/koalas/__init__.py	85.1% <0%> (-2.13%)	⬇️
databricks/koalas/indexing.py	94.26% <0%> (-0.63%)	⬇️
databricks/koalas/internal.py	96.42% <0%> (ø)	⬆️
databricks/koalas/missing/indexes.py	100% <0%> (ø)	⬆️
databricks/koalas/missing/series.py	100% <0%> (ø)	⬆️
databricks/koalas/numpy_compat.py	90% <0%> (ø)
... and 7 more

---

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 8a7a640...38d827b. Read the comment docs.

[softagram-bot]

Softagram Impact Report for pull/1054 (head commit: 38d827b)

⚠️ Copy paste found

ℹ️ frame.py: Copy paste fragment on line 5715 shared with ../namespace.py:

              on: Union[str, List[str], Tuple[str, ...], List[Tuple[str, ...]]] = None,
              left_on: Union[str, List[str], Tuple[s...(truncated 273 chars)

ℹ️ frame.py: Copy paste fragment on line 1474 shared with ../series.py:

    def to_latex(self, buf=None, columns=None, col_space=None, header=True, index=True,
                 na_rep='NaN',...(truncated 256 chars)

ℹ️ frame.py: Copy paste fragment inside the same file on lines 7213, 7296:

        # TODO: there is a similar logic to transpose in, for instance,
        #  DataFrame.any, Series.quantile. Maybe ...(truncated 1065 chars)

ℹ️ frame.py: Copy paste fragment inside the same file on lines 4844, 4865:

            sdf = self._sdf.select(
                self._internal.index_scols +
                [self._internal.scol_for(idx...(truncated 466 chars)

ℹ️ frame.py: Copy paste fragment inside the same file on lines 503, 910, 1854, 2799, 2883, 6677:

            sdf = self._sdf.select(
                self._internal.index_scols + [c._scol for c in applied])
            internal = self....(truncated 430 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/1054

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