Date is datetime.date(2013, 12, 30)
I am trying to get week number using
import datetime
datetime.date(2013, 12, 30).isocalendar()[1]
I am getting output as ,
1
Why i am not getting week number of last year , instead i am getting week number of current year?
Whats wrong i am doing here ?
You are doing nothing wrong, 2013/12/30 falls in week 1 of 2014, according to the ISO8601 week numbering standard:
The ISO 8601 definition for week 01 is the week with the year's first Thursday in it.
The Thursday in that week is 2014/01/02.
Other ways to explain the definition, from the same linked WikiPedia article:
It is the first week with a majority (four or more) of its days in January (ISO weeks start on Monday)
Its first day is the Monday nearest to 1 January.
It has 4 January in it. Hence the earliest possible dates are 29 December through 4 January, the latest 4 through 10 January.
It has the year's first working day in it, if Saturdays, Sundays and 1 January are not working days.
If you were looking for the last week number of a given year (52 or 53, depending on the year), I'd use December 28th, which is always guaranteed to be in the last week (because January 4th is always part of the first week of the next year):
def lastweeknumber(year):
return datetime.date(year, 12, 28).isocalendar()[1]
from datetime import date
from datetime import datetime
ndate='10/1/2016'
ndate = datetime.strptime(ndate, '%m/%d/%Y').strftime('%Y,%m,%d')
print('new format:',ndate)
d=ndate.split(',')
wkno = date(int(d[0]),int(d[1]),int(d[2])).isocalendar()[1]
print(wkno)
manually or read a date to a string and get the week number, play around with different formats.
Related
Since I want to get the last Wendnesday of every month, use pendulum.parse but sometimes 4 is last week or 5 is last week. How to get easily the day is last Wendnesday of month or not?
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You can use the calendar module from the standard library and compute all dates
calendar.weekday(year, month, day) Returns the day of the week (0 is
Monday) for year (1970–…), month (1–12), day (1–31).
As a helper, you can also use from the same module
calendar.monthrange(year, month) Returns weekday of first day of the
month and number of days in month, for the specified year and month.
I'm running Python 3.8.3 and I found something weird about the ISO Week format (%V) :
The first day and the last day of 2019 are both in week 1.
from datetime import date
print(date(2019, 1, 1).strftime('%Y-W%V'))
print(date(2019, 12, 29).strftime('%Y-W%V'))
print(date(2019, 12, 31).strftime('%Y-W%V'))
Output:
2019-W01
2019-W52
2019-W01
Why does it behave like that?
It is fully correct.
As you see in your dates, all of them are in 2019, so it is correct to get 2019 with %Y.
Week number is defined by ISO, and so one week could be considered in previous or in next year.
You need to use %G to get year of the week number (%V).
I'm trying to generate week number string using Python time module, considering week starts on Sunday.
If my interpretation of the official documentation is correct then this can be achieved by the following code:
import time
time.strftime("%U", time.localtime())
>> 37
My question is, is the above output correct? Shouldn't the output be 38 instead, considering the below details:
My timezone is IST (GMT+5:30)
import time
#Year
time.localtime()[0]
>> 2019
#Month
time.localtime()[1]
>> 9
#Day
time.localtime()[2]
>> 18
Yes, the output is correct. Week 1 started on January 6th, as that was the first Sunday in 2019. January 1st through 5th were week 0:
>>> time.strftime('%U', time.strptime("2019-1-1", "%Y-%m-%d"))
'00'
>>> time.strftime('%U', time.strptime("2019-1-6", "%Y-%m-%d"))
'01'
This is covered in the documentation:
All days in a new year preceding the first Sunday are considered to be in week 0.
You are perhaps looking for the ISO week date, but note that in this system the first day of the week is a Monday.
You can get the week number using that system with the datetime.date.isocalendar() method, or by formatting with %V:
>>> time.strftime("%V", time.localtime())
'38'
>>> from datetime import date
>>> date.today().isocalendar() # returns ISO year, week, and weekday
(2019, 38, 2)
>>> date.today().strftime("%V")
'38'
It's correct since you start counting from the first Sunday.
%U - week number of the current year, starting with the first Sunday as the first day of the first week
https://www.tutorialspoint.com/python/time_strftime.htm
It's correct. Since all days in a new year preceding the first Sunday are considered to be in week 0 (01/01 to 01/05), this week is the week 37.
I'm building an API for my college's timetable website. The default option is to look up today's timetable. However, the timetable system is using week numbering different to the one we normally use.
One of the 2 things I need to build the URL is the week number.
TIMETABLE_URL = 'http://timetable.ait.ie/reporting/textspreadsheet;student+set;id;{}?t=student+set+textspreadsheet&days=1-5&=&periods=3-20&=student+set+textspreadsheet&weeks={}&template=student+set+textspreadsheet'
Week numbering should start at this date: 27 Aug 2018 - 2 Sep 2018. Following this, week 2 would be 3 Sep 2018-9 Sep 2018 and so on. This should carry over New Years, the date of 31 Dec 2018-6 Jan 2019 would be week 19. This 'year' would have 52 weeks total.
I know how to check if a certain date is in between one of the ranges from above, but I want to avoid manually setting all the date ranges. How can I have a script know that, for example, it's in week 3 on 12 September?
Using datetime.datetime object:
from datetime import datetime
start = datetime.strptime('20180827', '%Y%m%d')
current = datetime.strptime('20180912', '%Y%m%d')
print((current - start).days//7 +1) # The week number
# Output: 3
This can also handle different years. Note that this only works when the start date is Monday.
I am trying to get a date based on a number of the week, but there are some annoyances.
The date.weekday() returns the day of the week where 0 in Monday and 6 is Sunday.
The %w directive of date.strftime() and date.strptime() uses the 0 for Sunday and 6 for Saturday.
This causes some really annoying issues when trying to figure out a date given a week number from date.weekday().
Is there a better way of getting a date from a week number?
EDIT:
Added the example.
import datetime
original_date = datetime.date(2014, 8, 24)
week_of_the_date = original_date.isocalendar()[1] # 34
day_of_the_date = original_date.isocalendar()[2] # 7
temp = '{0} {1} {2}'.format(*(2014, week_of_the_date, day_of_the_date-1))
date_from_week = datetime.datetime.strptime(temp, '%Y %W %w')
week_from_new_date = date_from_week.isocalendar()[1] # 35!!
EDIT 2:
I ultimately put the date stuff in the view (using jQuery UI), it has more consistent notions of weeks.
I think the Sunday vs. Monday distinction between weekday and strftime using %W is moot - you could use isoweekday to get those to line up, or %U in strftime if you wanted Sunday as the first day of the week. The real problem is that strftime, based on the underlying C function, determines the first week of the year differently than the ISO definition. With %W the docs say: " All days in a new year preceding the first Monday are considered to be in week 0". ISO calendars count the week containing the first Thursday as the first week, for reasons I do not understand.
Two ways I found to work with ISO weeks, either just getting datetime.date instances back or supporting a variety of operations, are:
this answer with a simple timedelta approach:
What's the best way to find the inverse of datetime.isocalendar()?
this third-party library: https://pypi.python.org/pypi/isoweek/