[Numpy-discussion] code review for datetime arange

Christopher Barker Chris.Barker@noaa....
Thu Jun 9 15:41:40 CDT 2011

Mark Wiebe wrote:
> Because of the nature of datetime and timedelta, arange has to be 
> slightly different than with all the other types. In particular, for 
> datetime the primary signature is np.arange(datetime, datetime, timedelta).
> I've implemented a simple extension which allows for another way to 
> specify a date range, as np.arange(datetime, timedelta, timedelta).

instead of, or in addition to, the above?

it seems you can pass in the following types:

(floats ?)

Are you essentially doing method overloading to determine what it all means?

How do you know if:

np.arange('2011', '2020', dtype='M8[Y]')

means you want from the years 2011 to 2020 or from 2011 to 4031?

>  >>> np.arange('today', 10, 3, dtype='M8')
> array(['2011-06-09', '2011-06-12', '2011-06-15', '2011-06-18'], 
> dtype='datetime64[D]')

so dtype 'M8' defaults to increments of days?

of course, I've lost track of the difference between 'M' and 'M8'

(I've never liked the dtype code anyway -- I far prefer np.float64 to 
'd', for instance)

Will there be a "linspace" for datetimes?


Christopher Barker, Ph.D.

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