Iterating through a range of dates in Python
Why are there two nested iterations? For me it produces the same list of data with only one iteration:
for single_date in (start_date + timedelta(n) for n in range(day_count)): print ...
And no list gets stored, only one generator is iterated over. Also the "if" in the generator seems to be unnecessary.
After all, a linear sequence should only require one iterator, not two.
Update after discussion with John Machin:
Maybe the most elegant solution is using a generator function to completely hide/abstract the iteration over the range of dates:
from datetime import date, timedeltadef daterange(start_date, end_date): for n in range(int((end_date - start_date).days)): yield start_date + timedelta(n)start_date = date(2013, 1, 1)end_date = date(2015, 6, 2)for single_date in daterange(start_date, end_date): print(single_date.strftime("%Y-%m-%d"))
NB: For consistency with the built-in
range() function this iteration stops before reaching the
end_date. So for inclusive iteration use the next day, as you would with
This might be more clear:
from datetime import date, timedeltastart_date = date(2019, 1, 1)end_date = date(2020, 1, 1)delta = timedelta(days=1)while start_date <= end_date: print(start_date.strftime("%Y-%m-%d")) start_date += delta
from datetime import datefrom dateutil.rrule import rrule, DAILYa = date(2009, 5, 30)b = date(2009, 6, 9)for dt in rrule(DAILY, dtstart=a, until=b): print dt.strftime("%Y-%m-%d")
This python library has many more advanced features, some very useful, like
relative deltas—and is implemented as a single file (module) that's easily included into a project.