confused on calculating date difference in days.
hello, I am strangely confused with a date calculation problem. the point is that I want to calculate difference in two dates in days. there are two aspects to this problem. firstly, I can't get a way to convert a string like 1/2/2005 in a genuan date object which is needed for calculation. now once this is done I will create a another date object with today = datetime.datetime.now() and then see the difference between this today and the string that I converted to date. now in the first place I can't recall how I can convert a string to a date. then now I don't know how to calculate difference in days between today and the string converted date. any help will be appreciated. regards, Krishnakant. -- http://mail.python.org/mailman/listinfo/python-list
Re: confused on calculating date difference in days.
On Tue, 16 Oct 2007 12:33:33 +0530, krishnakant Mane wrote:
firstly, I can't get a way to convert a string like 1/2/2005 in a
genuan date object which is needed for calculation.
Why? Split the string up, convert the parts to `int` and just create a
`datetime.date` object.
now once this is done I will create a another date object with
today = datetime.datetime.now()
and then see the difference between this today and the string that I
converted to date.
now in the first place I can't recall how I can convert a string to a date.
then now I don't know how to calculate difference in days between
today and the string converted date.
In [421]: '1/2/2005'.split('/')
Out[421]: ['1', '2', '2005']
In [422]: map(int, '1/2/2005'.split('/'))
Out[422]: [1, 2, 2005]
In [423]: month, day, year = map(int, '1/2/2005'.split('/'))
In [424]: a = datetime.date(year, month, day)
In [425]: b = datetime.date.today() - a
In [426]: b.days
Out[426]: 1017
Maybe you should read the docs next time. ;-)
Ciao,
Marc 'BlackJack' Rintsch
--
http://mail.python.org/mailman/listinfo/python-list
Re: confused on calculating date difference in days.
krishnakant Mane [EMAIL PROTECTED] writes: firstly, I can't get a way to convert a string like 1/2/2005 in a genuan date object which is needed for calculation. Until recently, this was a wart in the Python standard library: datetime objects exist in the 'datetime' module, but parsing strings to get date/time components was only available in the 'time' module. In Python 2.5, though, we have 'datetime.datetime.strptime' URL:http://docs.python.org/lib/datetime-datetime.html#l2h-634, which parses a string according to a specified format, and returns the corresponding datetime value. import datetime datetime.datetime.strptime(2007-10-16t17:40:00, %Y-%m-%dt%H:%M:%S) datetime.datetime(2007, 10, 16, 17, 40) now once this is done I will create a another date object with today = datetime.datetime.now() and then see the difference between this today and the string that I converted to date. That's simple: datetime objects support difference via the subtraction arithmetic operator, returning a datetime.timedelta instance URL:http://docs.python.org/lib/datetime-timedelta.html. value = datetime.datetime(2007, 10, 16, 15, 30, 45) value - datetime.datetime(2007, 10, 16, 15, 20, 00) datetime.timedelta(0, 645) value - datetime.datetime(2007, 10, 12, 8, 25, 19) datetime.timedelta(4, 25526) value - datetime.datetime(2007, 11, 26, 0, 0, 0) datetime.timedelta(-41, 55845) -- \ Experience is that marvelous thing that enables you to | `\ recognize a mistake when you make it again. -- Franklin P. | _o__)Jones | Ben Finney -- http://mail.python.org/mailman/listinfo/python-list
Re: confused on calculating date difference in days.
Marc 'BlackJack' Rintsch [EMAIL PROTECTED] writes: On Tue, 16 Oct 2007 12:33:33 +0530, krishnakant Mane wrote: firstly, I can't get a way to convert a string like 1/2/2005 in a genuan date object which is needed for calculation. Why? Split the string up, convert the parts to `int` and just create a `datetime.date` object. What, re-implement 'strptime' in every program that needs it? And then debug the result every time? Even if one doesn't have Python 2.5 or above, surely getting the string parsed into int values by the standard 'time.strptime' is better than re-implementing it every time. Maybe you should read the docs next time. ;-) Back at you. -- \ If you do not trust the source do not use this program. | `\—Microsoft Vista security dialogue | _o__) | Ben Finney -- http://mail.python.org/mailman/listinfo/python-list
Re: confused on calculating date difference in days.
On Tue, 16 Oct 2007 18:10:54 +1000, Ben Finney wrote: Marc 'BlackJack' Rintsch [EMAIL PROTECTED] writes: On Tue, 16 Oct 2007 12:33:33 +0530, krishnakant Mane wrote: firstly, I can't get a way to convert a string like 1/2/2005 in a genuan date object which is needed for calculation. Why? Split the string up, convert the parts to `int` and just create a `datetime.date` object. What, re-implement 'strptime' in every program that needs it? And then debug the result every time? Yes. Seems easier to me. :-) Even if one doesn't have Python 2.5 or above, surely getting the string parsed into int values by the standard 'time.strptime' is better than re-implementing it every time. Maybe you should read the docs next time. ;-) Back at you. Got me. I didn't know that `datetime` has a `strptime` now. I just looked at `date`. Ciao, Marc 'BlackJack' Rintsch -- http://mail.python.org/mailman/listinfo/python-list
Re: confused on calculating date difference in days.
hello, thanks all of you for providing valuable help. right now I am confused about the delta object. how can I extract the difference between two dates in terms of day using the delta object? I tried reading the python docs but did not understand the concept of delta object and how can I measure the difference in terms of days between two dates. I expect that the days would be integers. secondly the format of my date is actually 16/10/2007, and this is all in varchar field inside a postgresql database. I understand that datetime.datetime.strptime would convert this string 16/10/2007 into a date object which I can then compare with the current date created by datetime.now(). is that right? if yes then please explain me how I can get the delta object to give me results in days. regards, Krishnakant. -- http://mail.python.org/mailman/listinfo/python-list
Re: confused on calculating date difference in days.
krishnakant Mane wrote: hello, thanks all of you for providing valuable help. right now I am confused about the delta object. how can I extract the difference between two dates in terms of day using the delta object? I tried reading the python docs but did not understand the concept of delta object and how can I measure the difference in terms of days between two dates. I expect that the days would be integers. secondly the format of my date is actually 16/10/2007, and this is all in varchar field inside a postgresql database. I understand that datetime.datetime.strptime would convert this string 16/10/2007 into a date object which I can then compare with the current date created by datetime.now(). is that right? if yes then please explain me how I can get the delta object to give me results in days. The documentation is very clear about this: http://docs.python.org/lib/datetime-timedelta.html Instance attributes (read-only): days Between -9 and 9 inclusive seconds Between 0 and 86399 inclusive microseconds Between 0 and 99 inclusive So (date_a - date_b).days will give you what you need. Diez -- http://mail.python.org/mailman/listinfo/python-list
Re: confused on calculating date difference in days.
# Example import datetime def days_old(birth_year=1974,birth_month=12,birth_day=7): return (datetime.date.today() - datetime.date(birth_year,birth_month,birth_day) ).days days_old() 12000 krishnakant Mane wrote: hello, thanks all of you for providing valuable help. right now I am confused about the delta object. how can I extract the difference between two dates in terms of day using the delta object? I tried reading the python docs but did not understand the concept of delta object and how can I measure the difference in terms of days between two dates. I expect that the days would be integers. secondly the format of my date is actually 16/10/2007, and this is all in varchar field inside a postgresql database. I understand that datetime.datetime.strptime would convert this string 16/10/2007 into a date object which I can then compare with the current date created by datetime.now(). is that right? if yes then please explain me how I can get the delta object to give me results in days. regards, Krishnakant. -- Shane Geiger IT Director National Council on Economic Education [EMAIL PROTECTED] | 402-438-8958 | http://www.ncee.net Leading the Campaign for Economic and Financial Literacy begin:vcard fn:Shane Geiger n:Geiger;Shane org:National Council on Economic Education (NCEE) adr:Suite 215;;201 N. 8th Street;Lincoln;NE;68508;United States email;internet:[EMAIL PROTECTED] title:IT Director tel;work:402-438-8958 x-mozilla-html:FALSE url:http://www.ncee.net version:2.1 end:vcard -- http://mail.python.org/mailman/listinfo/python-list
