Python - Find Dates inbetween Dates

Question

I have an array of dates, they're sets of available dates only for a schedule, the unavailable dates not included. What I'd like to do is find the unavailable dates, what would be my best bet to accomplish this?

Note, I'll be converting them to unix time afterwards, so if the solution is converting them to unix time first, don't worry about doing it backwards! Any help is appreciated.

['2013-10-22', '2013-10-23', '2013-10-24', '2013-10-25', '2013-10-26', '2013-10-27', '2013-10-28', '2013-10-29', '2013-10-30', '2013-10-31', '2013-11-01', '2013-11-01', '2013-11-02', '2013-11-03', '2013-11-04', '2013-11-05', '2013-11-06', '2013-11-07', '2013-11-08', '2013-11-09', '2013-11-10', '2013-11-11', '2013-11-12', '2013-11-13', '2013-11-14', '2013-11-15', '2013-11-16', '2013-11-17', '2013-11-18', '2013-11-19', '2013-11-20', '2013-11-21', '2013-11-22', '2013-11-23', '2013-11-24', '2013-11-25', '2013-11-26', '2013-11-27', '2013-11-28', '2013-11-29', '2013-11-30', '2013-12-01', '2013-12-02', '2013-12-03', '2013-12-04', '2013-12-05', '2013-12-06', '2013-12-07', '2013-12-08', '2013-12-09', '2013-12-10', '2013-12-11', '2013-12-12', '2013-12-13', '2013-12-14', '2013-12-15', '2013-12-16', '2013-12-17', '2013-12-18', '2013-12-19', '2013-12-20', '2013-12-21', '2013-12-22', '2013-12-23', '2013-12-24', '2013-12-24', '2013-12-25', '2013-12-26', '2013-12-26', '2013-12-27', '2013-12-28', '2013-12-29', '2013-12-30', '2013-12-31', '2014-01-01', '2014-01-02', '2014-01-03', '2014-01-04', '2014-01-04', '2014-01-05', '2014-01-06', '2014-01-07', '2014-01-07', '2014-01-08', '2014-01-09', '2014-01-10', '2014-01-11', '2014-01-12', '2014-01-13', '2014-01-14', '2014-01-15', '2014-01-16', '2014-01-17', '2014-01-18', '2014-01-19', '2014-01-20', '2014-01-21', '2014-01-22', '2014-01-23', '2014-01-24', '2014-01-25', '2014-01-26', '2014-01-27', '2014-01-28', '2014-01-29', '2014-01-30', '2014-01-31', '2014-02-01', '2014-02-02', '2014-02-03', '2014-02-04', '2014-02-05', '2014-02-06', '2014-02-07', '2014-02-08', '2014-02-09', '2014-02-10', '2014-02-11', '2014-02-12', '2014-02-13', '2014-02-14', '2014-02-15', '2014-02-16', '2014-02-17', '2014-02-18', '2014-02-19', '2014-02-20', '2014-02-21', '2014-02-22', '2014-02-23', '2014-02-24', '2014-02-25', '2014-02-26', '2014-02-27', '2014-02-28', '2014-03-01', '2014-03-01', '2014-03-02', '2014-03-03', '2014-03-04', '2014-03-05', '2014-03-06', '2014-03-07', '2014-03-08', '2014-03-09', '2014-03-10', '2014-03-11', '2014-03-12', '2014-03-13', '2014-03-14', '2014-03-15', '2014-03-16', '2014-03-17', '2014-03-18', '2014-03-19', '2014-03-20', '2014-03-21', '2014-03-22', '2014-03-23', '2014-03-24', '2014-03-25', '2014-03-26', '2014-03-27', '2014-03-28', '2014-03-29', '2014-03-30', '2014-03-31', '2014-04-01', '2014-04-01', '2014-04-02', '2014-04-03', '2014-04-04', '2014-04-05', '2014-04-06', '2014-04-07', '2014-04-08', '2014-04-09', '2014-04-10', '2014-04-11', '2014-04-12', '2014-04-13', '2014-04-13', '2014-04-14', '2014-04-15', '2014-04-16', '2014-04-17', '2014-04-17', '2014-04-18', '2014-04-19', '2014-04-20', '2014-04-21', '2014-04-22', '2014-04-23', '2014-04-24', '2014-04-24', '2014-04-25', '2014-04-26', '2014-04-27', '2014-04-28', '2014-04-28', '2014-04-29', '2014-04-30', '2014-05-01', '2014-05-02', '2014-05-03', '2014-05-04', '2014-05-05', '2014-05-06', '2014-05-07', '2014-05-08', '2014-05-09', '2014-05-10', '2014-05-11', '2014-05-12', '2014-05-13', '2014-05-14', '2014-05-15', '2014-05-16', '2014-05-17', '2014-05-18', '2014-05-19', '2014-05-20', '2014-05-21', '2014-05-22', '2014-05-23', '2014-05-24', '2014-05-25', '2014-05-26', '2014-05-27', '2014-05-28', '2014-05-29', '2014-05-30', '2014-05-31', '2014-06-01', '2014-06-02', '2014-06-03', '2014-06-04', '2014-06-05', '2014-06-06', '2014-06-07', '2014-06-08', '2014-06-09', '2014-06-10', '2014-06-11', '2014-06-12', '2014-06-13', '2014-06-14', '2014-06-15', '2014-06-16', '2014-06-17', '2014-06-18', '2014-06-19', '2014-06-20', '2014-06-21', '2014-06-22', '2014-06-23', '2014-06-24', '2014-06-25', '2014-06-26', '2014-06-27', '2014-06-28', '2014-06-29', '2014-06-30', '2014-07-01', '2014-07-01', '2014-07-02', '2014-07-03', '2014-07-04', '2014-07-05', '2014-07-06', '2014-07-07', '2014-07-08', '2014-07-09', '2014-07-10', '2014-07-11', '2014-07-12', '2014-07-13', '2014-07-14', '2014-07-15', '2014-07-16', '2014-07-17', '2014-07-18', '2014-07-19', '2014-07-20', '2014-07-21', '2014-07-22', '2014-07-23', '2014-07-24', '2014-07-25', '2014-07-26', '2014-07-27', '2014-07-28', '2014-07-29', '2014-07-30', '2014-07-31', '2014-08-01', '2014-08-01', '2014-08-02', '2014-08-03', '2014-08-04', '2014-08-05', '2014-08-06', '2014-08-07', '2014-08-08', '2014-08-09', '2014-08-10', '2014-08-11', '2014-08-12', '2014-08-13', '2014-08-14', '2014-08-15', '2014-08-16', '2014-08-17', '2014-08-18', '2014-08-19', '2014-08-20', '2014-08-21', '2014-08-22', '2014-08-23', '2014-08-24', '2014-08-25', '2014-08-26', '2014-08-27', '2014-08-28', '2014-08-29', '2014-08-30', '2014-08-31', '2014-09-01', '2014-09-01', '2014-09-02', '2014-09-03', '2014-09-04', '2014-09-05', '2014-09-06', '2014-09-07', '2014-09-08', '2014-09-09', '2014-09-10', '2014-09-11', '2014-09-12', '2014-09-13', '2014-09-14', '2014-09-15', '2014-09-16', '2014-09-17', '2014-09-18', '2014-09-19', '2014-09-20', '2014-09-21', '2014-09-22', '2014-09-23', '2014-09-24', '2014-09-25', '2014-09-26', '2014-09-27', '2014-09-28', '2014-09-29', '2014-09-30', '2014-10-01', '2014-10-02', '2014-10-03', '2014-10-04', '2014-10-05', '2014-10-06', '2014-10-07', '2014-10-08', '2014-10-09', '2014-10-10', '2014-10-11', '2014-10-12', '2014-10-13', '2014-10-14', '2014-10-15', '2014-10-16', '2014-10-17', '2014-10-18', '2014-10-19', '2014-10-20', '2014-10-21', '2014-10-22', '2014-10-23', '2014-10-24', '2014-10-25', '2014-10-26', '2014-10-27', '2014-10-28', '2014-10-29', '2014-10-30', '2014-10-31', '2014-11-01', '2014-11-01', '2014-11-02', '2014-11-03', '2014-11-04', '2014-11-05', '2014-11-06', '2014-11-07', '2014-11-08', '2014-11-09', '2014-11-10', '2014-11-11', '2014-11-12', '2014-11-13', '2014-11-14', '2014-11-15', '2014-11-16', '2014-11-17', '2014-11-18', '2014-11-19', '2014-11-20', '2014-11-21', '2014-11-22', '2014-11-23', '2014-11-24', '2014-11-25', '2014-11-26', '2014-11-27', '2014-11-28', '2014-11-29', '2014-11-30', '2014-12-01', '2014-12-02', '2014-12-03', '2014-12-04', '2014-12-05', '2014-12-06', '2014-12-07', '2014-12-08', '2014-12-09', '2014-12-10', '2014-12-11', '2014-12-12', '2014-12-13', '2014-12-14', '2014-12-15', '2014-12-16', '2014-12-17', '2014-12-18', '2014-12-19', '2014-12-20', '2014-12-21', '2014-12-22', '2014-12-23', '2014-12-24', '2014-12-24', '2014-12-25', '2014-12-26', '2014-12-26', '2014-12-27', '2014-12-28', '2014-12-29', '2014-12-30', '2014-12-31', '2015-01-01', '2015-01-02', '2015-01-03', '2015-01-04', '2015-01-04', '2015-01-05', '2015-01-06', '2015-01-07', '2015-01-07', '2015-01-08', '2015-01-09', '2015-01-10', '2015-01-11', '2015-01-12', '2015-01-13', '2015-01-14', '2015-01-15', '2015-01-16', '2015-01-17', '2015-01-18', '2015-01-19', '2015-01-20', '2015-01-21', '2015-01-22', '2015-01-23', '2015-01-24', '2015-01-25', '2015-01-26', '2015-01-27', '2015-01-28', '2015-01-29', '2015-01-30', '2015-01-31', '2015-02-01', '2015-02-02', '2015-02-03', '2015-02-04', '2015-02-05', '2015-02-06', '2015-02-07', '2015-02-08', '2015-02-09', '2015-02-10', '2015-02-11', '2015-02-12', '2015-02-13', '2015-02-14', '2015-02-15', '2015-02-16', '2015-02-17', '2015-02-18', '2015-02-19', '2015-02-20', '2015-02-21', '2015-02-22', '2015-02-23', '2015-02-24', '2015-02-25', '2015-02-26', '2015-02-27', '2015-02-28', '2015-03-01', '2015-03-01', '2015-03-02', '2015-03-03', '2015-03-04', '2015-03-05', '2015-03-06', '2015-03-07', '2015-03-08', '2015-03-09', '2015-03-10', '2015-03-11', '2015-03-12', '2015-03-13', '2015-03-14', '2015-03-15', '2015-03-16', '2015-03-17', '2015-03-18', '2015-03-19', '2015-03-20', '2015-03-21', '2015-03-22', '2015-03-23', '2015-03-24', '2015-03-25', '2015-03-26', '2015-03-27', '2015-03-28', '2015-03-29', '2015-03-29', '2015-03-30', '2015-03-31', '2015-04-01', '2015-04-02', '2015-04-02', '2015-04-03', '2015-04-04', '2015-04-05', '2015-04-06', '2015-04-07', '2015-04-08', '2015-04-09', '2015-04-09', '2015-04-10', '2015-04-11', '2015-04-12', '2015-04-13', '2015-04-13', '2015-04-14', '2015-04-15', '2015-04-16', '2015-04-17', '2015-04-18', '2015-04-19', '2015-04-20', '2015-04-21', '2015-04-22', '2015-04-23', '2015-04-24', '2015-04-25', '2015-04-26', '2015-04-27', '2015-04-28', '2015-04-29', '2015-04-30', '2015-05-01', '2015-05-02', '2015-05-03', '2015-05-04', '2015-05-05', '2015-05-06', '2015-05-07', '2015-05-08', '2015-05-09', '2015-05-10', '2015-05-11', '2015-05-12', '2015-05-13', '2015-05-14', '2015-05-15', '2015-05-16', '2015-05-17', '2015-05-18', '2015-05-19', '2015-05-20', '2015-05-21', '2015-05-22', '2015-05-23', '2015-05-24', '2015-05-25', '2015-05-26', '2015-05-27', '2015-05-28', '2015-05-29', '2015-05-30', '2015-05-31', '2015-06-01', '2015-06-02', '2015-06-03', '2015-06-04', '2015-06-05', '2015-06-06', '2015-06-07', '2015-06-08', '2015-06-09', '2015-06-10', '2015-06-11', '2015-06-12', '2015-06-13', '2015-06-14', '2015-06-15', '2015-06-16', '2015-06-17', '2015-06-18', '2015-06-19', '2015-06-20', '2015-06-21', '2015-06-22', '2015-06-23', '2015-06-24', '2015-06-25', '2015-06-26', '2015-06-27', '2015-06-28', '2015-06-29', '2015-06-30', '2015-07-01', '2015-07-01', '2015-07-02', '2015-07-03', '2015-07-04', '2015-07-05', '2015-07-06', '2015-07-07', '2015-07-08', '2015-07-09', '2015-07-10', '2015-07-11', '2015-07-12', '2015-07-13', '2015-07-14', '2015-07-15', '2015-07-16', '2015-07-17', '2015-07-18', '2015-07-19', '2015-07-20', '2015-07-21', '2015-07-22', '2015-07-23', '2015-07-24', '2015-07-25', '2015-07-26', '2015-07-27', '2015-07-28', '2015-07-29', '2015-07-30', '2015-07-31', '2015-08-01', '2015-08-01', '2015-08-02', '2015-08-03', '2015-08-04', '2015-08-05', '2015-08-06', '2015-08-07', '2015-08-08', '2015-08-09', '2015-08-10', '2015-08-11', '2015-08-12', '2015-08-13', '2015-08-14', '2015-08-15', '2015-08-16', '2015-08-17', '2015-08-18', '2015-08-19', '2015-08-20', '2015-08-21', '2015-08-22', '2015-08-23', '2015-08-24', '2015-08-25', '2015-08-26', '2015-08-27', '2015-08-28', '2015-08-29', '2015-08-30', '2015-08-31', '2015-09-01', '2015-09-01', '2015-09-02', '2015-09-03', '2015-09-04', '2015-09-05', '2015-09-06', '2015-09-07', '2015-09-08', '2015-09-09', '2015-09-10', '2015-09-11', '2015-09-12', '2015-09-13', '2015-09-14', '2015-09-15', '2015-09-16', '2015-09-17', '2015-09-18', '2015-09-19', '2015-09-20', '2015-09-21', '2015-09-22', '2015-09-23', '2015-09-24', '2015-09-25', '2015-09-26', '2015-09-27', '2015-09-28', '2015-09-29', '2015-09-30', '2015-10-01', '2015-10-02', '2015-10-03', '2015-10-04', '2015-10-05', '2015-10-06', '2015-10-07', '2015-10-08', '2015-10-09', '2015-10-10', '2015-10-11', '2015-10-12', '2015-10-13', '2015-10-14', '2015-10-15', '2015-10-16', '2015-10-17', '2015-10-18', '2015-10-19', '2015-10-20', '2015-10-21']

Answer 1

I would do something like this -

from datetime import *
from dateutil import parser as dp

available = ['2013-10-22', '2013-10-23',  '2013-10-25', '2013-10-26', '2013-10-27', '2013-10-28', '2013-10-30']  
sorted_available = sorted(available, key=lambda d: map(int, d.split('-')))
first = dp.parse(sorted_available[0])
last = dp.parse(sorted_available[-1])
daysInRange = (last - first).days
booked = []
d = first
for x in range(0, daysInRange):
    d = d + timedelta(days=1)
    if not (d.strftime("%Y-%m-%d") in available):
        booked.append(d.strftime("%Y-%m-%d"))

print booked

Answer 2

from datetime import datetime, timedelta
available_date_strings = ['2013-01-01','2013-01-03','2013-01-15']
available_dates = [datetime.strptime(d, '%Y-%m-%d').date() \
                   for d in available_date_strings]
unavailable_dates = []
prev_day = available_dates[0]
while (prev_day < available_dates[-1]):
    the_date =  prev_day + timedelta(days=1)
    if the_date not in available_dates:
         unavailable_dates.append(the_date)
    prev_day = the_date

unavailable_dates =>
[datetime.date(2013, 1, 2),
 datetime.date(2013, 1, 4),
 datetime.date(2013, 1, 5),
 datetime.date(2013, 1, 6),
 datetime.date(2013, 1, 7),
 datetime.date(2013, 1, 8),
 datetime.date(2013, 1, 9),
 datetime.date(2013, 1, 10),
 datetime.date(2013, 1, 11),
 datetime.date(2013, 1, 12),
 datetime.date(2013, 1, 13),
 datetime.date(2013, 1, 14)]

Answer 3

You could convert all the dates to datetime objects first, and then iterate through them and check for holes. Or you could create two sets, one of all available dates, and then remove the available ones from that set.

>>> from datetime import datetime, timedelta
>>> available = list(map(lambda x: datetime.strptime(x, '%Y-%m-%d'), available))
>>> dateRange = available[-1] - available[0]
>>> allDays = set((available[0] + timedelta(days=i)) for i in range(dateRange.days))
>>> allDays - set(available)
{datetime.datetime(2013, 10, 26, 0, 0)}

(I took that one out from the original input; there weren’t any missing days)

Answer 4

I would simply map each date into an index number and mark off the ones which are not available. Then run through the list once to find the available dates. This will be an O(N) solution.

Mapping example: [..., '2013-10-22', '2013-10-25', ...] -> [..., 295, 298, ...]

October 22 is 295th day of the year 2013: http://www.soils.wisc.edu/cgi-bin/asig/doyCal.rb

Make sure you use the right starting point (epoch). You could use the unix epoch as well.