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ERR: DatetimeIndex creation inconsistencies between list and ndarray #11587

sinhrks opened this issue Nov 13, 2015 · 2 comments


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commented Nov 13, 2015

Setting invalid freq against ndarray(dtype=int) should raise ValueError.

import numpy as np
import pandas as pd

pd.DatetimeIndex(np.array([pd.Timestamp('2011-01-01').value, pd.Timestamp('2011-01-03').value]), freq='D')
# ValueError: Inferred frequency None from passed dates does not conform to passed frequency D

There seems to be 2 issues:

1. invalid frequency may set if data is list

pd.DatetimeIndex([pd.Timestamp('2011-01-01').value, pd.Timestamp('2011-01-03').value], freq='D')
# DatetimeIndex(['2011-01-01', '2011-01-03'], dtype='datetime64[ns]', freq='D')

2. ndarray data may raise unclear error message

pd.DatetimeIndex(np.array([pd.tslib.iNaT, pd.Timestamp('2011-01-01').value]), freq='D')
# ValueError: NaTType does not support time

@sinhrks sinhrks added this to the 0.17.1 milestone Nov 13, 2015

@sinhrks sinhrks changed the title BUG: DatetimeIndex creation inconsistencies between list and ndarray ERR: DatetimeIndex creation inconsistencies between list and ndarray Nov 13, 2015


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commented Nov 13, 2015

[1] is correct.

In [8]: pd.DatetimeIndex([pd.Timestamp('2011-01-01').value, pd.Timestamp('2011-01-03').value], freq='D')
Out[8]: DatetimeIndex(['2011-01-01', '2011-01-03'], dtype='datetime64[ns]', freq='D')

In [9]: pd.DatetimeIndex([pd.Timestamp('2011-01-01').value, pd.Timestamp('2011-01-03').value], freq='D').inferred_freq

you can set any freq you want on a DatetimeIndex. It doesn't infer in this case because its too short.

@jreback jreback modified the milestones: Next Major Release, 0.17.1 Nov 13, 2015

@jbrockmendel jbrockmendel added this to DatetimeIndex Bugs in DatetimeArray Refactor Nov 16, 2018


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commented Dec 7, 2018

@sinhrks the list and ndarray behavior now match. Can you confirm that part 1 of the issue is resolved. I'll take a look at the second part.

@jbrockmendel jbrockmendel referenced this issue Dec 8, 2018


BUG: Assorted DatetimeIndex bugfixes #24157

1 of 1 task complete

@jreback jreback modified the milestones: Contributions Welcome, 0.24.0 Dec 13, 2018

@jbrockmendel jbrockmendel moved this from DTI/DTA Constructor Issues to Done in DatetimeArray Refactor Dec 15, 2018

@jbrockmendel jbrockmendel removed this from Done in DatetimeArray Refactor Jan 4, 2019

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