[Numpy-discussion] Accessing fields of the object stored in numpy array

[Friedrich Romstedt]

Hello Vishal,

2010/2/18 Vishal Rana <ranavishal at gmail.com>:

> a = np.array([dt.datetime(2010, 2, 17), dt.datetime(2010, 2, 16),
> dt.datetime(2010, 2, 15)])
> b = np.array([dt.datetime(2010, 2, 14), dt.datetime(2010, 2, 13),
> dt.datetime(2010, 2, 12)])

> c=a-b
> c.days (a numpy array of days difference) like:
> array([3, 3, 3])

I think a (rather slow) solution would be to use:

def days(timedelta):
    return timedelta.days

udays = numpy.vectorize(days)

and applying the ufunc udays() on your dtype = numpy.object array like:

c_days = udays(c)

numpy.vectorize() turns an ordinary function into an ufunc.  This
means, that the ufunc created can take ndarrays and the days()
function will be applied to all elements.

hth,
Friedrich