2.3. Datetime Time Deltas¶
2.3.1. Timedelta object¶
Shifting datetime objects:
from datetime import datetime
gagarin = datetime(1961, 4, 12, 6, 7)
armstrong = datetime(1969, 7, 21, 2, 56, 15)
between_dates = armstrong - gagarin
str(between_dates) # '3021 days, 20:49:15'
between_dates # datetime.timedelta(days=3021, seconds=74955)
between_dates.days # 3021
between_dates.seconds # 74955
between_dates.total_seconds() # 261089355.0 (days * seconds per day + seconds)
2.3.2. Time Shift¶
2.3.3. Simple Shifts¶
Simple timedelta shifts:
from datetime import timedelta, datetime
gagarin = datetime(1961, 4, 12)
gagarin - timedelta(minutes=15)
# datetime.datetime(1961, 4, 11, 23, 45)
gagarin + timedelta(minutes=10)
# datetime.datetime(1961, 4, 12, 0, 10)
Simple timedelta shifts:
from datetime import timedelta, datetime
armstrong = datetime(1969, 7, 21, 2, 56, 15)
armstrong - timedelta(hours=21)
# datetime.datetime(1969, 7, 20, 5, 56, 15)
armstrong + timedelta(hours=5)
# datetime.datetime(1969, 7, 21, 7, 56, 15)
Simple timedelta shifts:
from datetime import timedelta, date
sputnik = date(1957, 10, 4)
sputnik + timedelta(days=5)
# datetime.date(1957, 10, 9)
sputnik - timedelta(days=3)
# datetime.date(1957, 10, 1)
Simple timedelta shifts:
from datetime import datetime, timedelta
gagarin = datetime(1961, 4, 12)
gagarin + timedelta(weeks=2)
# datetime.datetime(1961, 4, 26, 0, 0)
gagarin - timedelta(weeks=3)
# datetime.datetime(1961, 3, 22, 0, 0)
2.3.4. Complex Shifts¶
Complex timedelta shifts:
from datetime import timedelta, datetime
armstrong = datetime(1969, 7, 21, 2, 56, 15)
armstrong - timedelta(days=2, hours=21)
# datetime.datetime(1969, 7, 18, 5, 56, 15)
Complex timedelta shifts:
from datetime import timedelta, datetime
armstrong = datetime(1969, 7, 21, 2, 56, 15)
duration = timedelta(
weeks=3,
days=2,
hours=21,
minutes=5,
seconds=12,
milliseconds=10,
microseconds=55)
# datetime.timedelta(days=23, seconds=75912, microseconds=10055)
between_dates = armstrong - duration
# datetime.datetime(1969, 6, 27, 5, 51, 2, 989945)
2.3.5. Month Shifts¶
Subtract month from datetime:
from datetime import timedelta, date
MONTH = timedelta(days=30.436875)
gagarin = date(1961, 4, 12)
gagarin - MONTH
# datetime.date(1961, 3, 13)
Subtract month from datetime:
from calendar import monthlen
from datetime import timedelta, date
def month_before(dt):
MONTH = monthlen(dt.year, dt.month)
return dt - timedelta(days=MONTH)
gagarin = date(1961, 4, 12)
month_before(gagarin)
# datetime.date(1961, 3, 13)
2.3.6. Duration¶
Duration between two datetimes:
from datetime import datetime
SECOND = 1
MINUTE = 60 * SECOND
HOUR = 60 * MINUTE
DAY = 24 * HOUR
MONTH = 30.436875 * DAY # Average days a month in solar calendar
YEAR = 365.2425 * DAY # Solar calendar
def duration(dt):
years, seconds = divmod(dt.total_seconds(), YEAR)
months, seconds = divmod(seconds, MONTH)
days, seconds = divmod(seconds, DAY)
hours, seconds = divmod(dt.seconds, HOUR)
minutes, seconds = divmod(seconds, MINUTE)
return {
'years': int(years),
'months': int(months),
'days': int(days),
'hours': int(hours),
'minutes': int(minutes),
'seconds': int(seconds),
}
gagarin = datetime(1961, 4, 12, 6, 7)
armstrong = datetime(1969, 7, 21, 2, 56, 15)
dt = armstrong - gagarin
# datetime.timedelta(days=3021, seconds=74955)
duration(dt)
# {'years': 8, 'months': 3, 'days': 8, 'hours': 20, 'minutes': 49, 'seconds': 15}
2.3.7. Assignments¶
"""
* Assignment: Datetime Timedelta Period
* Complexity: easy
* Lines of code: 15 lines
* Time: 13 min
English:
1. Use data from "Given" section (see below)
2. Given period is the time between Gagarin launch and Armstrong first step on the Moon
3. Assume:
a. year = 365.2425 days
* month = 30.436875 days
4. From current date subtract this period
5. Print calculated date
6. How old were you at the given moment?
Polish:
1. Użyj danych z sekcji "Given" (patrz poniżej)
2. Podany jest czas, który upłynął między startem Gagarina a pierwszym krokiem Armstronga na Księżycu
3. Uwzględnij założenie:
a. rok = 365.2425 dni
* miesiąc = 30.436875 dni
4. Od obecnej chwili odejmij ten czas
5. Wyświetl wyliczoną datę
6. Ile miałeś wtedy lat?
Given:
* 8 years
* 3 months
* 8 days
* 20 hours
* 49 minutes
* 15 seconds
Tests:
# This will change every second
>>> result
{'years': 42,
'months': 7,
'days': 28,
'hours': 7,
'minutes': 54,
'seconds': 46}
"""
# Given
from datetime import datetime, timedelta
SECOND = 1
MINUTE = 60 * SECOND
HOUR = 60 * MINUTE
DAY = 24 * HOUR
MONTH = 30.436875 * DAY
YEAR = 365.2425 * DAY
shift = int(8*YEAR + 3*MONTH + 9*DAY + 49*MINUTE + 15*SECOND)
birthday = datetime(1970, 1, 1, 0, 0, 0)