In the end what you have is a maths issue. If every 4 years we have an extra day lets then dived the timedelta in days, not by 365 but 365*4 + 1, that would give you the amount of 4 years. Then divide it again by 4. timedelta / ((365*4) +1) / 4 = timedelta * 4 / (365*4 +1)
I would use datetime.date data type instead, as it is simpler when it comes to checking how many years, months and days have passed:
now = date.today()
birthday = date(1993, 4, 4)
print("you are", now.year - birthday.year, "years,", now.month - birthday.month, "months and",
now.day - birthday.day, "days old")
Output:
you are 27 years, 7 months and 11 days old
I use timedelta when I need to perform arithmetic on a specific date:
age = now - birthday
print("addition of days to a date: ", birthday + timedelta(days=age.days))
Output:
addition of days to a date: 2020-11-15
Here's a updated DOB function, which calculates birthdays the same way humans do:
import datetime
import locale
# Source: https://en.wikipedia.org/wiki/February_29
PRE = [
'US',
'TW',
]
POST = [
'GB',
'HK',
]
def get_country():
code, _ = locale.getlocale()
try:
return code.split('_')[1]
except IndexError:
raise Exception('Country cannot be ascertained from locale.')
def get_leap_birthday(year):
country = get_country()
if country in PRE:
return datetime.date(year, 2, 28)
elif country in POST:
return datetime.date(year, 3, 1)
else:
raise Exception('It is unknown whether your country treats leap year '
+ 'birthdays as being on the 28th of February or '
+ 'the 1st of March. Please consult your country\'s '
+ 'legal code for in order to ascertain an answer.')
def age(dob):
today = datetime.date.today()
years = today.year - dob.year
try:
birthday = datetime.date(today.year, dob.month, dob.day)
except ValueError as e:
if dob.month == 2 and dob.day == 29:
birthday = get_leap_birthday(today.year)
else:
raise e
if today < birthday:
years -= 1
return years
print(age(datetime.date(1988, 2, 29)))
How exact do you need it to be? td.days / 365.25 will get you pretty close, if you're worried about leap years.
def age(dob):
import datetime
today = datetime.date.today()
if today.month < dob.month or \
(today.month == dob.month and today.day < dob.day):
return today.year - dob.year - 1
else:
return today.year - dob.year
>>> import datetime
>>> datetime.date.today()
datetime.date(2009, 12, 1)
>>> age(datetime.date(2008, 11, 30))
1
>>> age(datetime.date(2008, 12, 1))
1
>>> age(datetime.date(2008, 12, 2))
0
I liked John Mee's solution for its simplicity, and I am not that concerned about how, on Feb 28 or March 1 when it is not a leap year, to determine age of people born on Feb 29. But here is a tweak of his code which I think addresses the complaints:
def age(dob):
import datetime
today = datetime.date.today()
age = today.year - dob.year
if ( today.month == dob.month == 2 and
today.day == 28 and dob.day == 29 ):
pass
elif today.month < dob.month or \
(today.month == dob.month and today.day < dob.day):
age -= 1
return age
I'll suggest Pyfdate
What is pyfdate?
Given Python's goal to be a powerful and easy-to-use scripting language, its features for working with dates and times are not as user-friendly as they should be. The purpose of pyfdate is to remedy that situation by providing features for working with dates and times that are as powerful and easy-to-use as the rest of Python.
the tutorial
I came across this question and found Adams answer the most helpful https://stackoverflow.com/a/765862/2964689
But there was no python example of his method but here's what I ended up using.
input: datetime object
output: integer age in whole years
def age(birthday):
birthday = birthday.date()
today = date.today()
years = today.year - birthday.year
if (today.month < birthday.month or
(today.month == birthday.month and today.day < birthday.day)):
years = years - 1
return years
Late to the party, but this will give you the age (in years) accurately and easily:
b = birthday
today = datetime.datetime.today()
age = today.year - b.year + (today.month - b.month > 0 or
(today.month == b.month > 0 and
today.day - b.day > 0))
This is the solution I worked out, I hope can help ;-)
def menor_edad_legal(birthday):
""" returns true if aged<18 in days """
try:
today = time.localtime()
fa_divuit_anys=date(year=today.tm_year-18, month=today.tm_mon, day=today.tm_mday)
if birthday>fa_divuit_anys:
return True
else:
return False
except Exception, ex_edad:
logging.error('Error menor de edad: %s' % ex_edad)
return True
Get the number of days, then divide by 365.2425 (the mean Gregorian year) for years. Divide by 30.436875 (the mean Gregorian month) for months.
If you're trying to check if someone is 18 years of age, using timedelta will not work correctly on some edge cases because of leap years. For example, someone born on January 1, 2000, will turn 18 exactly 6575 days later on January 1, 2018 (5 leap years included), but someone born on January 1, 2001, will turn 18 exactly 6574 days later on January 1, 2019 (4 leap years included). Thus, you if someone is exactly 6574 days old, you can't determine if they are 17 or 18 without knowing a little more information about their birthdate.
The correct way to do this is to calculate the age directly from the dates, by subtracting the two years, and then subtracting one if the current month/day precedes the birth month/day.
Yet another 3rd party lib not mentioned here is mxDateTime (predecessor of both python datetime and 3rd party timeutil) could be used for this task.
The aforementioned yearsago would be:
from mx.DateTime import now, RelativeDateTime
def years_ago(years, from_date=None):
if from_date == None:
from_date = now()
return from_date-RelativeDateTime(years=years)
First parameter is expected to be a DateTime instance.
To convert ordinary datetime to DateTime you could use this for 1 second precision):
def DT_from_dt_s(t):
return DT.DateTimeFromTicks(time.mktime(t.timetuple()))
or this for 1 microsecond precision:
def DT_from_dt_u(t):
return DT.DateTime(t.year, t.month, t.day, t.hour,
t.minute, t.second + t.microsecond * 1e-6)
And yes, adding the dependency for this single task in question would definitely be an overkill compared even with using timeutil (suggested by Rick Copeland).
Even though this thread is already dead, might i suggest a working solution for this very same problem i was facing. Here it is (date is a string in the format dd-mm-yyyy):
def validatedate(date):
parts = date.strip().split('-')
if len(parts) == 3 and False not in [x.isdigit() for x in parts]:
birth = datetime.date(int(parts[2]), int(parts[1]), int(parts[0]))
today = datetime.date.today()
b = (birth.year * 10000) + (birth.month * 100) + (birth.day)
t = (today.year * 10000) + (today.month * 100) + (today.day)
if (t - 18 * 10000) >= b:
return True
return False
this function returns the difference in years between two dates (taken as strings in ISO format, but it can easily modified to take in any format)
import time
def years(earlydateiso, laterdateiso):
"""difference in years between two dates in ISO format"""
ed = time.strptime(earlydateiso, "%Y-%m-%d")
ld = time.strptime(laterdateiso, "%Y-%m-%d")
#switch dates if needed
if ld < ed:
ld, ed = ed, ld
res = ld[0] - ed [0]
if res > 0:
if ld[1]< ed[1]:
res -= 1
elif ld[1] == ed[1]:
if ld[2]< ed[2]:
res -= 1
return res
First off, at the most detailed level, the problem can't be solved exactly. Years vary in length, and there isn't a clear "right choice" for year length.
That said, get the difference in whatever units are "natural" (probably seconds) and divide by the ratio between that and years. E.g.
delta_in_days / (365.25)
delta_in_seconds / (365.25*24*60*60)
...or whatever. Stay away from months, since they are even less well defined than years.
import datetime
def check_if_old_enough(years_needed, old_date):
limit_date = datetime.date(old_date.year + years_needed, old_date.month, old_date.day)
today = datetime.datetime.now().date()
old_enough = False
if limit_date <= today:
old_enough = True
return old_enough
def test_ages():
years_needed = 30
born_date_Logan = datetime.datetime(1988, 3, 5)
if check_if_old_enough(years_needed, born_date_Logan):
print("Logan is old enough")
else:
print("Logan is not old enough")
born_date_Jessica = datetime.datetime(1997, 3, 6)
if check_if_old_enough(years_needed, born_date_Jessica):
print("Jessica is old enough")
else:
print("Jessica is not old enough")
test_ages()
This is the code that the Carrousel operator was running in Logan's Run film ;)
Source: Stackoverflow.com