I have the following code to do this, but how can I do it better? Right now I think it's better than nested loops, but it starts to get Perl-one-linerish when you have a generator in a list comprehension.
day_count = (end_date - start_date).days + 1
for single_date in [d for d in (start_date + timedelta(n) for n in range(day_count)) if d <= end_date]:
print strftime("%Y-%m-%d", single_date.timetuple())
start_date
and end_date
variables are datetime.date
objects because I don't need the timestamps. (They're going to be used to generate a report).For a start date of 2009-05-30
and an end date of 2009-06-09
:
2009-05-30
2009-05-31
2009-06-01
2009-06-02
2009-06-03
2009-06-04
2009-06-05
2009-06-06
2009-06-07
2009-06-08
2009-06-09
Why not try:
import datetime as dt
start_date = dt.datetime(2012, 12,1)
end_date = dt.datetime(2012, 12,5)
total_days = (end_date - start_date).days + 1 #inclusive 5 days
for day_number in range(total_days):
current_date = (start_date + dt.timedelta(days = day_number)).date()
print current_date
import datetime
from dateutil.rrule import DAILY,rrule
date=datetime.datetime(2019,1,10)
date1=datetime.datetime(2019,2,2)
for i in rrule(DAILY , dtstart=date,until=date1):
print(i.strftime('%Y%b%d'),sep='\n')
OUTPUT:
2019Jan10
2019Jan11
2019Jan12
2019Jan13
2019Jan14
2019Jan15
2019Jan16
2019Jan17
2019Jan18
2019Jan19
2019Jan20
2019Jan21
2019Jan22
2019Jan23
2019Jan24
2019Jan25
2019Jan26
2019Jan27
2019Jan28
2019Jan29
2019Jan30
2019Jan31
2019Feb01
2019Feb02
Pandas is great for time series in general, and has direct support for date ranges.
import pandas as pd
daterange = pd.date_range(start_date, end_date)
You can then loop over the daterange to print the date:
for single_date in daterange:
print (single_date.strftime("%Y-%m-%d"))
It also has lots of options to make life easier. For example if you only wanted weekdays, you would just swap in bdate_range. See http://pandas.pydata.org/pandas-docs/stable/timeseries.html#generating-ranges-of-timestamps
The power of Pandas is really its dataframes, which support vectorized operations (much like numpy) that make operations across large quantities of data very fast and easy.
EDIT: You could also completely skip the for loop and just print it directly, which is easier and more efficient:
print(daterange)
Using pendulum.period:
import pendulum
start = pendulum.from_format('2020-05-01', 'YYYY-MM-DD', formatter='alternative')
end = pendulum.from_format('2020-05-02', 'YYYY-MM-DD', formatter='alternative')
period = pendulum.period(start, end)
for dt in period:
print(dt.to_date_string())
import datetime
def daterange(start, stop, step_days=1):
current = start
step = datetime.timedelta(step_days)
if step_days > 0:
while current < stop:
yield current
current += step
elif step_days < 0:
while current > stop:
yield current
current += step
else:
raise ValueError("daterange() step_days argument must not be zero")
if __name__ == "__main__":
from pprint import pprint as pp
lo = datetime.date(2008, 12, 27)
hi = datetime.date(2009, 1, 5)
pp(list(daterange(lo, hi)))
pp(list(daterange(hi, lo, -1)))
pp(list(daterange(lo, hi, 7)))
pp(list(daterange(hi, lo, -7)))
assert not list(daterange(lo, hi, -1))
assert not list(daterange(hi, lo))
assert not list(daterange(lo, hi, -7))
assert not list(daterange(hi, lo, 7))
For those who are interested in Pythonic functional way:
from datetime import date, timedelta
from itertools import count, takewhile
for d in takewhile(lambda x: x<=date(2009,6,9), map(lambda x:date(2009,5,30)+timedelta(days=x), count())):
print(d)
Numpy's arange
function can be applied to dates:
import numpy as np
from datetime import datetime, timedelta
d0 = datetime(2009, 1,1)
d1 = datetime(2010, 1,1)
dt = timedelta(days = 1)
dates = np.arange(d0, d1, dt).astype(datetime)
The use of astype
is to convert from numpy.datetime64
to an array of datetime.datetime
objects.
Here's code for a general date range function, similar to Ber's answer, but more flexible:
def count_timedelta(delta, step, seconds_in_interval):
"""Helper function for iterate. Finds the number of intervals in the timedelta."""
return int(delta.total_seconds() / (seconds_in_interval * step))
def range_dt(start, end, step=1, interval='day'):
"""Iterate over datetimes or dates, similar to builtin range."""
intervals = functools.partial(count_timedelta, (end - start), step)
if interval == 'week':
for i in range(intervals(3600 * 24 * 7)):
yield start + datetime.timedelta(weeks=i) * step
elif interval == 'day':
for i in range(intervals(3600 * 24)):
yield start + datetime.timedelta(days=i) * step
elif interval == 'hour':
for i in range(intervals(3600)):
yield start + datetime.timedelta(hours=i) * step
elif interval == 'minute':
for i in range(intervals(60)):
yield start + datetime.timedelta(minutes=i) * step
elif interval == 'second':
for i in range(intervals(1)):
yield start + datetime.timedelta(seconds=i) * step
elif interval == 'millisecond':
for i in range(intervals(1 / 1000)):
yield start + datetime.timedelta(milliseconds=i) * step
elif interval == 'microsecond':
for i in range(intervals(1e-6)):
yield start + datetime.timedelta(microseconds=i) * step
else:
raise AttributeError("Interval must be 'week', 'day', 'hour' 'second', \
'microsecond' or 'millisecond'.")
For completeness, Pandas also has a period_range
function for timestamps that are out of bounds:
import pandas as pd
pd.period_range(start='1/1/1626', end='1/08/1627', freq='D')
What about the following for doing a range incremented by days:
for d in map( lambda x: startDate+datetime.timedelta(days=x), xrange( (stopDate-startDate).days ) ):
# Do stuff here
For a generic version:
for d in map( lambda x: startTime+x*stepTime, xrange( (stopTime-startTime).total_seconds() / stepTime.total_seconds() ) ):
# Do stuff here
Note that .total_seconds() is only supported after python 2.7 If you are stuck with an earlier version you can write your own function:
def total_seconds( td ):
return float(td.microseconds + (td.seconds + td.days * 24 * 3600) * 10**6) / 10**6
This might be more clear:
from datetime import date, timedelta
start_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
I have a similar problem, but I need to iterate monthly instead of daily.
This is my solution
import calendar
from datetime import datetime, timedelta
def days_in_month(dt):
return calendar.monthrange(dt.year, dt.month)[1]
def monthly_range(dt_start, dt_end):
forward = dt_end >= dt_start
finish = False
dt = dt_start
while not finish:
yield dt.date()
if forward:
days = days_in_month(dt)
dt = dt + timedelta(days=days)
finish = dt > dt_end
else:
_tmp_dt = dt.replace(day=1) - timedelta(days=1)
dt = (_tmp_dt.replace(day=dt.day))
finish = dt < dt_end
Example #1
date_start = datetime(2016, 6, 1)
date_end = datetime(2017, 1, 1)
for p in monthly_range(date_start, date_end):
print(p)
Output
2016-06-01
2016-07-01
2016-08-01
2016-09-01
2016-10-01
2016-11-01
2016-12-01
2017-01-01
Example #2
date_start = datetime(2017, 1, 1)
date_end = datetime(2016, 6, 1)
for p in monthly_range(date_start, date_end):
print(p)
Output
2017-01-01
2016-12-01
2016-11-01
2016-10-01
2016-09-01
2016-08-01
2016-07-01
2016-06-01
for i in range(16):
print datetime.date.today() + datetime.timedelta(days=i)
You can generate a series of date between two dates using the pandas library simply and trustfully
import pandas as pd
print pd.date_range(start='1/1/2010', end='1/08/2018', freq='M')
You can change the frequency of generating dates by setting freq as D, M, Q, Y (daily, monthly, quarterly, yearly )
from datetime import date,timedelta
delta = timedelta(days=1)
start = date(2020,1,1)
end=date(2020,9,1)
loop_date = start
while loop_date<=end:
print(loop_date)
loop_date+=delta
Use the dateutil
library:
from datetime import date
from dateutil.rrule import rrule, DAILY
a = 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 delta
s—and is implemented as a single file (module) that's easily included into a project.
> pip install DateTimeRange
from datetimerange import DateTimeRange
def dateRange(start, end, step):
rangeList = []
time_range = DateTimeRange(start, end)
for value in time_range.range(datetime.timedelta(days=step)):
rangeList.append(value.strftime('%m/%d/%Y'))
return rangeList
dateRange("2018-09-07", "2018-12-25", 7)
Out[92]:
['09/07/2018',
'09/14/2018',
'09/21/2018',
'09/28/2018',
'10/05/2018',
'10/12/2018',
'10/19/2018',
'10/26/2018',
'11/02/2018',
'11/09/2018',
'11/16/2018',
'11/23/2018',
'11/30/2018',
'12/07/2018',
'12/14/2018',
'12/21/2018']
Show the last n days from today:
import datetime
for i in range(0, 100):
print((datetime.date.today() + datetime.timedelta(i)).isoformat())
Output:
2016-06-29
2016-06-30
2016-07-01
2016-07-02
2016-07-03
2016-07-04
This function has some extra features:
error checking in case the end is older than the start
import datetime
from datetime import timedelta
DATE_FORMAT = '%Y/%m/%d'
def daterange(start, end):
def convert(date):
try:
date = datetime.datetime.strptime(date, DATE_FORMAT)
return date.date()
except TypeError:
return date
def get_date(n):
return datetime.datetime.strftime(convert(start) + timedelta(days=n), DATE_FORMAT)
days = (convert(end) - convert(start)).days
if days <= 0:
raise ValueError('The start date must be before the end date.')
for n in range(0, days):
yield get_date(n)
start = '2014/12/1'
end = '2014/12/31'
print list(daterange(start, end))
start_ = datetime.date.today()
end = '2015/12/1'
print list(daterange(start, end))
Slightly different approach to reversible steps by storing range
args in a tuple.
def date_range(start, stop, step=1, inclusive=False):
day_count = (stop - start).days
if inclusive:
day_count += 1
if step > 0:
range_args = (0, day_count, step)
elif step < 0:
range_args = (day_count - 1, -1, step)
else:
raise ValueError("date_range(): step arg must be non-zero")
for i in range(*range_args):
yield start + timedelta(days=i)
You can use Arrow
:
This is example from the docs, iterating over hours:
from arrow import Arrow
>>> start = datetime(2013, 5, 5, 12, 30)
>>> end = datetime(2013, 5, 5, 17, 15)
>>> for r in Arrow.range('hour', start, end):
... print repr(r)
...
<Arrow [2013-05-05T12:30:00+00:00]>
<Arrow [2013-05-05T13:30:00+00:00]>
<Arrow [2013-05-05T14:30:00+00:00]>
<Arrow [2013-05-05T15:30:00+00:00]>
<Arrow [2013-05-05T16:30:00+00:00]>
To iterate over days, you can use like this:
>>> start = Arrow(2013, 5, 5)
>>> end = Arrow(2013, 5, 5)
>>> for r in Arrow.range('day', start, end):
... print repr(r)
(Didn't check if you can pass datetime.date
objects, but anyways Arrow
objects are easier in general)
Can't* believe this question has existed for 9 years without anyone suggesting a simple recursive function:
from datetime import datetime, timedelta
def walk_days(start_date, end_date):
if start_date <= end_date:
print(start_date.strftime("%Y-%m-%d"))
next_date = start_date + timedelta(days=1)
walk_days(next_date, end_date)
#demo
start_date = datetime(2009, 5, 30)
end_date = datetime(2009, 6, 9)
walk_days(start_date, end_date)
Output:
2009-05-30
2009-05-31
2009-06-01
2009-06-02
2009-06-03
2009-06-04
2009-06-05
2009-06-06
2009-06-07
2009-06-08
2009-06-09
Edit: *Now I can believe it -- see Does Python optimize tail recursion? . Thank you Tim.
This is the most human-readable solution I can think of.
import datetime
def daterange(start, end, step=datetime.timedelta(1)):
curr = start
while curr < end:
yield curr
curr += step
import datetime
def daterange(start, stop, step=datetime.timedelta(days=1), inclusive=False):
# inclusive=False to behave like range by default
if step.days > 0:
while start < stop:
yield start
start = start + step
# not +=! don't modify object passed in if it's mutable
# since this function is not restricted to
# only types from datetime module
elif step.days < 0:
while start > stop:
yield start
start = start + step
if inclusive and start == stop:
yield start
# ...
for date in daterange(start_date, end_date, inclusive=True):
print strftime("%Y-%m-%d", date.timetuple())
This function does more than you strictly require, by supporting negative step, etc. As long as you factor out your range logic, then you don't need the separate day_count
and most importantly the code becomes easier to read as you call the function from multiple places.
Source: Stackoverflow.com