[SciPy-Dev] Baffled by type_check.datetime_data

Robert Kern robert.kern@gmail....
Wed Apr 28 11:44:56 CDT 2010


On Wed, Apr 28, 2010 at 11:41, David Goldsmith <d.l.goldsmith@gmail.com> wrote:
> On Wed, Apr 28, 2010 at 8:57 AM, Robert Kern <robert.kern@gmail.com> wrote:
>>
>> On Tue, Apr 27, 2010 at 20:57, David Goldsmith <d.l.goldsmith@gmail.com>
>> wrote:
>> >>>> np.version.version
>> > '1.4.0'
>> >>>> from numpy.lib.type_check import datetime_data as dtd
>> >>>> help(dtd)
>> > Help on function datetime_data in module numpy.lib.type_check:
>> >
>> > datetime_data(dtype)
>> >     Return (unit, numerator, denominator, events) from a datetime dtype
>> >
>> >>>> np.dtype(np.datetime_)
>> > dtype('datetime64[us]')
>> >>>> dtd(np.datetime_)
>>
>> datatime_data() takes a dtype, not a scalar type.
>>
>> --
>> Robert Kern
>
> How is np.datetime_ not a dtype, and how is
>
>>>> np.dtype(np.datetime_)
> dtype('datetime64[us]')
>
> _not_ an indication that it isn't a dtype?

How *is* it an indication that it is a dtype? The scalar types can be
coerced to dtypes, but they are not dtype objects themselves, just
like strings like '>i4' are str objects, not dtype objects but they
can be coerced to dtype objects.

> How do I create a dtype object
> that datetime_data will recognize?

You just did it!

np.dtype(np.datetime_)

-- 
Robert Kern

"I have come to believe that the whole world is an enigma, a harmless
enigma that is made terrible by our own mad attempt to interpret it as
though it had an underlying truth."
  -- Umberto Eco


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