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DataFrame._init_dict handles columns with nan incorrectly if columns passed separately

good first issue

Needs TestsUnit test(s) needed to prevent regressionsUnit test(s) needed to prevent regressions

Status: Closed (completed).

#16894 In pandas-dev/pandas;

· by kernc was closed on Jan 21, 2020

Aggregate fails with mixed types in grouping series

good first issue

Needs TestsUnit test(s) needed to prevent regressionsUnit test(s) needed to prevent regressions

Status: Closed (completed).

#16916 In pandas-dev/pandas;

· by nreeve17 was closed on Jan 21, 2020

BUG: __getitem__ on MultiIndex with empty slice raises

good first issue

Needs TestsUnit test(s) needed to prevent regressionsUnit test(s) needed to prevent regressions

Status: Closed (completed).

#15454 In pandas-dev/pandas;

· by TomAugspurger was closed on Jan 21, 2020

BUG: .iloc indexing with duplicates

Bug

Dtype ConversionsUnexpected or buggy dtype conversionsUnexpected or buggy dtype conversions

IndexingRelated to indexing on series/frames, not to indexes themselvesRelated to indexing on series/frames, not to indexes themselves

Status: Closed (completed).

#15686 In pandas-dev/pandas;

· by toobaz was closed on Mar 11, 2020

.loc interprets slice as positional rather than label-based when setting

Bug

IndexingRelated to indexing on series/frames, not to indexes themselvesRelated to indexing on series/frames, not to indexes themselves

Status: Closed (completed).

#16121 In pandas-dev/pandas;

· by toobaz was closed on Mar 8, 2020

resample.apply flattens column index when more than 3 levels

good first issue

Needs TestsUnit test(s) needed to prevent regressionsUnit test(s) needed to prevent regressions

Resampleresample methodresample method

Status: Closed (completed).

#16231 In pandas-dev/pandas;

· by jmarrec was closed on Jan 21, 2020

IntervalIndex get_indexer may return -1 for values that are in the index

good first issue

Needs TestsUnit test(s) needed to prevent regressionsUnit test(s) needed to prevent regressions

Status: Closed (completed).

#16410 In pandas-dev/pandas;

· by nateyoder was closed on Jan 21, 2020

.loc Multiindex DateTime slicing failures

good first issue

Needs TestsUnit test(s) needed to prevent regressionsUnit test(s) needed to prevent regressions

Status: Closed (completed).

#16699 In pandas-dev/pandas;

· by attack68 was closed on Jan 21, 2020

Index gets lost when DataFrame melt method is used

API Design

ReshapingConcat, Merge/Join, Stack/Unstack, ExplodeConcat, Merge/Join, Stack/Unstack, Explode

Status: Closed (completed).

#17440 In pandas-dev/pandas;

· by NiklasKeck was closed on Jul 9, 2020

BUG/API: pivot_table with multi-index columns only

Bug

MultiIndex

ReshapingConcat, Merge/Join, Stack/Unstack, ExplodeConcat, Merge/Join, Stack/Unstack, Explode

Status: Closed (completed).

#17038 In pandas-dev/pandas;

· by chris-b1 was closed on Jan 15, 2020

BUG: Calling DataFrame.stack on an out-of-order column MultiIndex leads to swapped values

good first issue

Needs TestsUnit test(s) needed to prevent regressionsUnit test(s) needed to prevent regressions

Status: Closed (completed).

#18265 In pandas-dev/pandas;

· by tudorprodan was closed on Jan 24, 2020

numpy.split on non-UTC, tz-aware data undergoes UTC roundtrip

good first issue

Needs TestsUnit test(s) needed to prevent regressionsUnit test(s) needed to prevent regressions

Status: Closed (completed).

#14042 In pandas-dev/pandas;

· by isacarnekvist was closed on Mar 21, 2020

BUG: crosstab cannot normalize multiple columns for the index

good first issue

Needs TestsUnit test(s) needed to prevent regressionsUnit test(s) needed to prevent regressions

Status: Closed (completed).

#15150 In pandas-dev/pandas;

· by hurcy was closed on Jan 21, 2020

Assignment to multiple columns only works if they existed before

Bug

IndexingRelated to indexing on series/frames, not to indexes themselvesRelated to indexing on series/frames, not to indexes themselves

Status: Closed (completed).

#13658 In pandas-dev/pandas;

· by jzwinck was closed on Mar 14, 2020

Setting DataFrame of Python objects and MultiIndex columns wth single-element NDFrame inserts list

good first issue

Needs TestsUnit test(s) needed to prevent regressionsUnit test(s) needed to prevent regressions

Status: Closed (completed).

#14592 In pandas-dev/pandas;

· by toobaz was closed on Jan 21, 2020

Concatenation of category value counts mixes up the index order

Bug

CategoricalCategorical Data TypeCategorical Data Type

good first issue

Needs TestsUnit test(s) needed to prevent regressionsUnit test(s) needed to prevent regressions

Status: Closed (completed).

#14600 In pandas-dev/pandas;

· by jbao was closed on Jan 21, 2020

groupby type coercion dependent on presence of datetime column in grouped data

good first issue

Needs TestsUnit test(s) needed to prevent regressionsUnit test(s) needed to prevent regressions

Status: Closed (completed).

#14849 In pandas-dev/pandas;

· by wes-turner was closed on Jan 21, 2020

DataFrameGroupBy fillna swallows exceptions.

good first issue

Needs TestsUnit test(s) needed to prevent regressionsUnit test(s) needed to prevent regressions

Status: Closed (completed).

#14955 In pandas-dev/pandas;

· by RobertasA was closed on Jan 21, 2020

When running set_index on a categorical to a MultiIndex, it gets coerced to a string.

good first issue

Needs TestsUnit test(s) needed to prevent regressionsUnit test(s) needed to prevent regressions

Status: Closed (completed).

#15058 In pandas-dev/pandas;

· by thequackdaddy was closed on Jan 21, 2020

pd.Series.equals() fails for Series containing iterable objects

AlgosNon-arithmetic algos: value_counts, factorize, sorting, isin, clip, shift, diffNon-arithmetic algos: value_counts, factorize, sorting, isin, clip, shift, diff

good first issue

Needs TestsUnit test(s) needed to prevent regressionsUnit test(s) needed to prevent regressions

Status: Closed (completed).

#20676 In pandas-dev/pandas;

· by bfollinprm was closed on Jul 13, 2020

API/BUG: center=True in expanding operations returns non-sensical results

Bug

good first issue

Windowrolling, ewma, expandingrolling, ewma, expanding

Status: Closed (completed).

#20647 In pandas-dev/pandas;

· by jorisvandenbossche was closed on Jul 14, 2020

Modifying dataframe with float values using .iloc and boolean indexing raises ValueError

good first issue

Needs TestsUnit test(s) needed to prevent regressionsUnit test(s) needed to prevent regressions

Status: Closed (completed).

#20627 In pandas-dev/pandas;

· by karih was closed on Jun 13, 2020

Error when using .loc[integer] with object Index (also) containing floats

IndexingRelated to indexing on series/frames, not to indexes themselvesRelated to indexing on series/frames, not to indexes themselves

Status: Closed (completed).

#19456 In pandas-dev/pandas;

· by toobaz was closed on Feb 22, 2020

reset_index() on MultiIndexed empty dataframe does not preserve dtypes

MultiIndex

ReshapingConcat, Merge/Join, Stack/Unstack, ExplodeConcat, Merge/Join, Stack/Unstack, Explode

Status: Closed (completed).

#19602 In pandas-dev/pandas;

· by alberto-dellera was closed on Jun 23, 2020

pd.crosstab(s1, s2) keeps dummy MultiIndex as columns if both s1 and s2 have tuple name

Bug

ReshapingConcat, Merge/Join, Stack/Unstack, ExplodeConcat, Merge/Join, Stack/Unstack, Explode

Status: Closed (completed).

#18321 In pandas-dev/pandas;

· by toobaz was closed on Jan 17, 2020