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Preserve subclass family on reshape operations #15563

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delgadom opened this issue Mar 4, 2017 · 0 comments · Fixed by #18929
Closed

Preserve subclass family on reshape operations #15563

delgadom opened this issue Mar 4, 2017 · 0 comments · Fixed by #18929
Labels
API Design Reshaping Concat, Merge/Join, Stack/Unstack, Explode Subclassing Subclassing pandas objects
Milestone
0.23.0

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@delgadom
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delgadom commented Mar 4, 2017

Subclassed Series and DataFrames with custom _constructor, _constructor_sliced, and _constructor_expanddim methods return pandas Series and DataFrame objects on reshape operations:

>>> import numpy as np, pandas as pd
>>> import pandas.util.testing as tm
>>> df = tm.SubclassedDataFrame(np.random.random((4,5)))
>>> df
          0         1         2         3         4
0  0.151944  0.948561  0.639122  0.718071  0.296193
1  0.004606  0.978378  0.827614  0.479320  0.495945
2  0.158874  0.535476  0.173194  0.065292  0.365851
3  0.772392  0.105038  0.671064  0.164165  0.795803
>>> type(df)
<class 'pandas.util.testing.SubclassedDataFrame'>

Slicing operations use _constructor_sliced:

>>> type(df[0])
<class 'pandas.util.testing.SubclassedSeries'>

Reshape operations return regular pandas objects:

>>> type(df.stack())
<class 'pandas.core.series.Series'>

It would be great if this returned a SublcassedSeries. Same goes for unstack and pivot.
@delgadom delgadom changed the title Preserve subclass family on reshape operations (e.g. stack/unstack) Preserve subclass family on reshape operations Mar 4, 2017
@delgadom delgadom mentioned this issue Mar 4, 2017
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@jreback jreback added API Design Reshaping Concat, Merge/Join, Stack/Unstack, Explode labels Mar 4, 2017
@jreback jreback added this to the Next Major Release milestone Mar 7, 2017
@jreback jreback mentioned this issue Mar 11, 2017
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4 tasks
@delgadom delgadom mentioned this issue Mar 11, 2017
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This was referenced Dec 20, 2017
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Merged
@jreback jreback modified the milestones: Next Major Release, 0.23.0 Dec 26, 2017
@jorisvandenbossche jorisvandenbossche added the Subclassing Subclassing pandas objects label Dec 7, 2020
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Labels
API Design Reshaping Concat, Merge/Join, Stack/Unstack, Explode Subclassing Subclassing pandas objects
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Milestone
0.23.0
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@jreback @jorisvandenbossche @delgadom