Using rrule to assign days to relevant months

Question

I was able to list the days between two dates using rrule like so:

from dateutil import rrule
from datetime import datetime

a = '20180306'
b = '20180506'

for dt in rrule.rrule(rrule.DAILY,
                  dtstart = datetime.strptime(a, '%Y%m%d'),
                  until = datetime.strptime(b, '%Y%m%d')):
    print (dt.strftime('%Y%m%d'))

the output given is:

20180306
20180307
...
20180408
20180409
...
20180506

How can I go about assigning these days to their relevant months to give an output of:

March-18: 26 days
April-18: 30 days
May-18: 6 days

I am also curious about how to extend this to include hours in the calculation ie.

March-18: 11.9 days

Thanks black.mamba

Answer 1

You can use itertools.groupby and extract the length of each group. In the below example, both grouper and res are lazy iterators, so you can extract results by iteration.

from dateutil import rrule
from datetime import datetime
from itertools import groupby

a = '20180306'
b = '20180506'

rule = rrule.rrule(rrule.DAILY,
                   dtstart=datetime.strptime(a, '%Y%m%d'),
                   until=datetime.strptime(b, '%Y%m%d'))

grouper = groupby(rule, key=lambda x: x.strftime('%B-%y'))

res = ((i, len(list(j))) for i, j in grouper)

for month, count in res:
    print('{0}: {1} days'.format(month, count))

March-18: 26 days
April-18: 30 days
May-18: 6 days