How to apply a rule to datetime variables?

Question

I have the following day types:

daytypes = {
    'Holidays_1': (
        date(2017, 4, 20),
        date(2017, 7, 10)
    ),
    'Holidays_2': (
        date(2017, 2, 5),
        date(2017, 5, 12),
        date(2017, 12, 14)
    )
}

I want to know if the new date is a labour day (Monday-Friday) that is located 1 day before any holiday, and it is not a holiday itself.

For example, I have the following three datetime variables:

from datetime import datetime
dt1 = datetime.strptime("2017-02-04 11:12:20.0", "%Y-%m-%d %H:%M:%S.%f")
dt2 = datetime.strptime("2017-05-11 20:00:00.0", "%Y-%m-%d %H:%M:%S.%f")
dt3 = datetime.strptime("2017-02-06 12:00:00.0", "%Y-%m-%d %H:%M:%S.%f")

Only dt2 corresponds to the specified rule.

How can I do this?

@binu.py: Please specify what exactly is unclear and I will elaborate. — Dinosaurius, Aug 08 '17 at 14:53
One hint for you: `timedelta` can be used to add or subtract a day from a `datetime`. — Mark Ransom, Aug 08 '17 at 14:53

binu.py · Answer 1 · 2017-08-08T15:30:02.917

1

try this

from datetime import datetime as date
from datetime import timedelta, datetime

daytypes = {
    'Holidays_1': (
        date(2017, 4, 20),
        date(2017, 7, 10)
    ),
    'Holidays_2': (
        date(2017, 2, 5),
        date(2017, 5, 12),
        date(2017, 12, 14)
    )
}

holidays = []
for d in daytypes:
    holidays.extend(daytypes[d])

dt2 = datetime.strptime("2017-05-11 20:00:00.0", "%Y-%m-%d %H:%M:%S.%f")

for h in holidays:
    if h-dt2 < timedelta(1) and h-dt2 > timedelta(0):
        return True

edited Aug 08 '17 at 15:30

answered Aug 08 '17 at 15:06

binu.py

1,137
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It prints `True` for any date in my case. – Dinosaurius Aug 08 '17 at 15:17
I have updated my answer, please check, if you still get True for everything may be you are subtracting a future date from past date which is giving you negative day difference. you might want to handle that – binu.py Aug 08 '17 at 15:23
So, just running your example for `2017-05-11` I get `True False True True False`. But the answer should be True, – Dinosaurius Aug 08 '17 at 15:26
try now please @Dinosaurius – binu.py Aug 08 '17 at 15:31
Thanks for your help, but I used slightly different solution that I posted here as my answer. – Dinosaurius Aug 09 '17 at 07:09

MDL · Answer 2 · 2017-08-08T15:34:37.440

You can use the weekday() function to get what day of the week is your date object. The function returns an integer from 0 (monday) to 6 (sunday).

For example:

>>> from datetime import datetime, date
>>> dt1 = datetime.strptime("2017-02-04 11:12:20.0", "%Y-%m-%d %H:%M:%S.%f")
>>> holiday1 = date(2017, 02, 05)
>>> # Is the holiday one day ahead of the date?
>>> print date(dt1.year, dt1.month, dt1.day + 1) == holiday1 
True
>>> # Is the date a weekday?
>>> print dt1.weekday() in range(0,4) # Days from 0 to 4 are working days
False

Documentation is here: https://docs.python.org/2/library/datetime.html#datetime.date.weekday

Edit: You can use a for loop to iterate over each of your holidays:

for holiday_tuple in daytypes.keys():
    for holiday in holiday_tuple:
        # Do whatever you need here
        print date(dtx.year, dtx.month, dtx.day + 1) == holiday

Where dtx is any of the declared datetime objects. You could also use an additionnal for loop to iterate over a list of datetime objects.

In my case I have a dictionary of `daytypes`, not just 1 holiday. — Dinosaurius, Aug 08 '17 at 15:15

vielkind · Answer 3 · 2017-08-08T15:17:46.413

0

Here is a quick function to accomplish this. The function takes your dictionary of holidays and will evaluate the input date against those holidays and will return whether the input date is a weekend, within 1 day of a holiday, or a weekday not within one day of a holiday. You can change the functions to return more or less detail if needed, but this should fit the needs you describe.

def check_holidays(holidays, input_date):
    if input_date.weekday() >= 5:
        return 'Is a weekend date'
    for holiday, holiday_dates in holidays.items():
        holiday_range = []
        for h_date in holiday_dates:
            holiday_range.append(h_date)
            holiday_range.append(h_date - timedelta(days=1))
        if input_date.date() in holiday_range:
            return 'Date is within 1 day of a holiday'
    return 'Date is a weekday and not within 1 day of a holiday'

edited Aug 08 '17 at 15:17

answered Aug 08 '17 at 15:06

vielkind

2,840
1
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I get this error `AttributeError: type object 'datetime.datetime' has no attribute 'timedelta'`, when I run `check_holidays(daytypes,dt2)` – Dinosaurius Aug 08 '17 at 15:14
I see. Since you're doing `from datetime import datetime` you should add `timedelta` to your import to read `from datetime import datetime, timedelta`. Then you can drop `datetime` from the function and call `timedelta` directly. I've updated the code to show this. – vielkind Aug 08 '17 at 15:17
Hmm, it gives me now `Date is a weekday and not within 1 day of a holiday` for all entries. – Dinosaurius Aug 08 '17 at 15:22

score 0 · Accepted Answer · answered Aug 08 '17 at 15:30

0

I solved it this way:

holidays = []
for d in daytypes:
    holidays.extend(daytypes[d])

if (dt.isoweekday() >= 1 and dt.isoweekday() <= 5 and date(dt.year, dt.month, dt.day + 1) in holidays):
    print "Date is within 1 day of a holiday."
else:
    print "Date is a weekday and not within 1 day of a holiday."

answered Aug 08 '17 at 15:30

Dinosaurius

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nice one @Dinosaurius – binu.py Aug 09 '17 at 13:02
@binu.py except that this fails when the day is the last day of the month and the holiday is the first of the next month. Any 12/31 for example. – Mark Ransom Aug 09 '17 at 17:51
I think if you use timedelta it wont – binu.py Aug 09 '17 at 17:53

How to apply a rule to datetime variables?

4 Answers4