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python-2.7python-3.xrangegeneric-programming
abukaj
abukaj

Reputation: 2712

Is there an implementation of range() which is not limited to integers?

The Python range() built-in function is limited to integers.

I need a more generic function of similar signature range(start, stop, step), where start, stop and step may be of any types given that:

The function may be used (for example) to obtain a sequence of days of the year:

range(datetime.datetime(2015, 1, 1),
      datetime.datetime(2016, 1, 1),
      datetime.timedelta(1))

I know I can easily write such function by myself. However, I am looking for efficient existing solutions in some popular package (like numpy or scipy), working with both Python 2 and Python 3.

I have already tried to combine itertools.takewhile with itertools.count, however the latter seems to be limited to numbers.

Upvotes: 0

Views: 61

Answers (1)

scotty3785
scotty3785

Reputation: 7006

You can do this with a simple generator. The following example works with floats, integers and datetime.

With datetime you just need to clearly specify the exact date (1 Jan 2016) not just 2016 and clearly specify the time delta (timedelta(days=1) not timedelta(1))

import datetime

def range2(start,stop,step):
    value = start
    while value <= stop:
        yield value
        value += step

for date in range2(datetime.datetime(2015,1,1),datetime.datetime(2016,1,1),datetime.timedelta(days=1)):
    print(date)

As for off-the-shelf solutions there is arange in numpy but I haven't tested that with datetime.

>>> from numpy import arange
>>> arange(0.5, 5, 1.5)
array([0.5, 2.0, 3.5])

Upvotes: 1

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