CODEWITHSUNDEEP
pythondatecalendar
mike
mike

Reputation: 23811

Count Dates in Python

I am trying to count the number of Friday the 13ths per year from 1950-2050 using Python (I know, a little late). I am not familiar with any date/calendar packages to use. Any thoughts?

Upvotes: 2

Views: 5866

Answers (6)

Shohida Abdullayeva
Shohida Abdullayeva

Reputation: 1

from datetime import *
from time import strptime
yil = input("yilni kiritnig:: ")
kun1 = "01/01/"+yil
kun1 = datetime.strptime(kun1, "%d/%m/%Y")
while 1:
    if kun1.strftime("%A") == "Friday":
        break
    kun1 = kun1 + timedelta(days=1)
count = 0
while 1:
    if int(kun1.strftime("%Y")) == int(yil)+1:
        break
    if kun1.strftime("%d") == "13":
        count+=1
    kun1=kun1+timedelta(days=7)
print(count)

Upvotes: 0

Raymond Hettinger
Raymond Hettinger

Reputation: 226316

This has a direct solution. Use sum to count the number of times where the 13th of the month is a Friday:

>>> from datetime import datetime # the function datetime from module datetime
>>> sum(datetime(year, month, 13).weekday() == 4 
        for year in range(1950, 2051) for month in range(1,13))
174

Upvotes: 7

eumiro
eumiro

Reputation: 212885

While other solutions are clear and simple, the following one is more "calendarist". You will need the dateutil package, which is installable as a package:

from datetime import datetime
from dateutil import rrule

fr13s = list(rrule.rrule(rrule.DAILY,
                         dtstart=datetime(1950,1,13),
                         until=datetime(2050,12,13),
                         bymonthday=[13],
                         byweekday=[rrule.FR]))
# this returns a list of 174 datetime objects

You see these five arguments of rrule.rrule: Take every rrule.DAILY (day) between dtstart and until where bymonthday is 13 and byweekday is rrule.FR (Friday).

Upvotes: 0

Endophage
Endophage

Reputation: 21473

the datetime.date class has a weekday() function that gives you the day of the week (indexed from 0) as an integer, so Friday is 4. There's also isoweekday() that indexes days from 1, it's up to you which you prefer.

Anyway, a simple solution would be:

friday13 = 0
months = range(1,13)
for year in xrange(1950, 2051):
    for month in months:
        if date(year, month, 13).weekday() == 4:
            friday13 += 1

Upvotes: 4

Mark Tolonen
Mark Tolonen

Reputation: 177674

Sounds like homework. Hint (weekday 4 is a Friday):

import datetime
print(datetime.datetime(1950,1,13).weekday())

Upvotes: 0

Senthil Kumaran
Senthil Kumaran

Reputation: 56841

Is it some kind of exercise or homework? I faintly remember of having solved it. I can give you a hint, I seem to have used Calendar.itermonthdays2 Of course there should be other ways to solve it as well.

Upvotes: 0

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