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PERF: HDFStore iterator can use slices to represent iterator when where=None #10310

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jreback opened this issue Jun 8, 2015 · 1 comment
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Enhancement IO HDF5 read_hdf, HDFStore Performance Memory or execution speed performance

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@jreback
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jreback commented Jun 8, 2015

from SO

In [2]: df = DataFrame(np.random.randn(1000,2),columns=list('AB'))

In [3]: df.to_hdf('test.h5','df',mode='w',format='table',data_columns=True)

In [4]: i = pd.read_hdf('test.h5','df',chunksize=10)

In [5]: i
Out[5]: <pandas.io.pytables.TableIterator at 0x108f397d0>

In [6]: i.coordinates
Out[6]: 
Int64Index([  0,   1,   2,   3,   4,   5,   6,   7,   8,   9, 
            ...
            990, 991, 992, 993, 994, 995, 996, 997, 998, 999], dtype='int64', length=1000)

These coordinates could be represented by slice(0,1000,10) in this case

@jreback jreback added Enhancement Performance Memory or execution speed performance IO HDF5 read_hdf, HDFStore Difficulty Intermediate labels Jun 8, 2015
@jreback jreback added this to the 0.17.0 milestone Jun 8, 2015
@jreback jreback modified the milestones: Next Major Release, 0.17.0 Aug 15, 2015
@mroeschke mroeschke removed this from the Contributions Welcome milestone Oct 13, 2022
@mroeschke
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Seems like this hasn't gotten traction in a while so closing

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Labels
Enhancement IO HDF5 read_hdf, HDFStore Performance Memory or execution speed performance
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