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 Duration
* Complexity: easy
* Lines of code: 2 lines
* Time: 3 min
English:
1. Use data from "Given" section (see below)
2. Calculate how many years passed between Gagarin's launch
and Armstrong's first step on the Moon
3. Assume:
a. year = 365.2425 days
b. month = 30.436875 days
4. Result round to one decimal place
5. Compare result with "Tests" section (see below)
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
b. miesiąc = 30.436875 dni
4. Rezultat zaokrąglij jednego miejsca po przecinku
5. Porównaj wyniki z sekcją "Tests" (patrz poniżej)
Tests:
>>> assert type(result) is float, \
'Variable `result` has invalid type, must be a float'
>>> result
8.3
"""
# Given
from datetime import datetime, timedelta
DAY = 1
MONTH = 30.436875 * DAY
YEAR = 365.2425 * DAY
GAGARIN = datetime(1961, 4, 12, 6, 7)
ARMSTRONG = datetime(1969, 7, 21, 2, 56, 15)
"""
* Assignment: Datetime Timedelta Age
* Complexity: easy
* Lines of code: 6 lines
* Time: 11 min
English:
1. Use data from "Given" section (see below)
2. How old was Yuri Gagarin when he was launched to space?
3. How old was Neil Armstrong when he made a first step on the Moon?
4. Result round to full years
5. Mind, that there are two different objects: `date` and `datetime`
6. Compare result with "Tests" section (see below)
Polish:
1. Użyj danych z sekcji "Given" (patrz poniżej)
2. Ile miał lat Juri Gagarin kiedy wystartował w kosmos?
3. Ile lat miał Neil Armstrong kiedy zrobił pierwszy krok na Księżycu?
4. Rezultat zaokrąglij do pełnych lat
5. Mind, that there are two different objects: `date` and `datetime`
6. Porównaj wyniki z sekcją "Tests" (patrz poniżej)
Tests:
>>> assert type(gagarin_age) is int, \
'Variable `gagarin_age` has invalid type, must be a int'
>>> assert type(armstrong_age) is int, \
'Variable `armstrong_age` has invalid type, must be a int'
>>> gagarin_age
27
>>> armstrong_age
39
"""
# Given
from datetime import datetime, date
DAY = 1
MONTH = 30.436875 * DAY
YEAR = 365.2425 * DAY
GAGARIN_BIRTHDAY = date(1934, 3, 9)
GAGARIN_LAUNCH = datetime(1961, 4, 12, 6, 7)
ARMSTRONG_BIRTHDAY = date(1930, 8, 5)
ARMSTRONG_STEP = datetime(1969, 7, 21, 2, 56, 15)
gagarin_age = ... # int: Gagarin's age when he was launched to space
armstrong_age = ... # int: Armstrong's age when he made a first step on the Moon
"""
* Assignment: Datetime Timedelta Period
* Complexity: easy
* Lines of code: 2 lines
* Time: 8 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:
* 8 years
* 3 months
* 8 days
* 20 hours
* 49 minutes
* 15 seconds
3. Assume:
a. year = 365.2425 days
b. month = 30.436875 days
4. Define `result: timedelta` representing given period
Polish:
1. Użyj danych z sekcji "Given" (patrz poniżej)
2. Podany jest czas, który upłynął między startem Gagarina a pierwszym krokiem Armstronga na Księżycu:
* 8 lat
* 3 miesięcy
* 8 dni
* 20 godzin
* 49 minut
* 15 sekund
3. Uwzględnij założenie:
a. rok = 365.2425 dni
b. miesiąc = 30.436875 dni
4. Zdefiniuj `result: timedelta` reprezentujące dany okres
Tests:
>>> assert type(result) is timedelta, \
'Variable `result` has invalid type, must be a timedelta'
>>> result
datetime.timedelta(days=3022, seconds=24609)
"""
# Given
from datetime import timedelta
SECOND = 1
MINUTE = 60 * SECOND
HOUR = 60 * MINUTE
DAY = 24 * HOUR
MONTH = 30.436875 * DAY
YEAR = 365.2425 * DAY
# 8 years
# 3 months
# 8 days
# 20 hours
# 49 minutes
# 15 seconds
result = ... # timedelta: representing given period
"""
* Assignment: Datetime Timedelta Dict
* Complexity: easy
* Lines of code: 13 lines
* Time: 13 min
English:
1. Use data from "Given" section (see below)
2. Given period `DATA` is the time between Gagarin launch and Armstrong first step on the Moon
3. Assume:
a. year = 365.2425 days
b. month = 30.436875 days
4. Define `result: dict[str, int]` representing period
Polish:
1. Użyj danych z sekcji "Given" (patrz poniżej)
2. Podany jest okres `DATA`, który upłynął między startem Gagarina a pierwszym krokiem Armstronga na Księżycu
3. Uwzględnij założenie:
a. rok = 365.2425 dni
b. miesiąc = 30.436875 dni
4. Zdefiniuj `result: dict[str, int]` reprezentujący okres
Given:
* 8 years
* 3 months
* 8 days
* 20 hours
* 49 minutes
* 15 seconds
Tests:
>>> assert type(result) is dict, \
'Variable `result` has invalid type, must be a dict'
>>> result.keys()
dict_keys(['years', 'months', 'days', 'hours', 'minutes', 'seconds'])
>>> assert all(type(value) is int for value in result.values()), \
'All elements in `result` must be an int'
>>> result
{'years': 8, 'months': 3, 'days': 9, 'hours': 6, 'minutes': 50, 'seconds': 9}
"""
# Given
from datetime import timedelta
SECOND = 1
MINUTE = 60 * SECOND
HOUR = 60 * MINUTE
DAY = 24 * HOUR
MONTH = 30.436875 * DAY
YEAR = 365.2425 * DAY
DATA = timedelta(days=3022, seconds=24609)
result = {
'years': ...,
'months': ...,
'days': ...,
'hours': ...,
'minutes': ...,
'seconds': ...,
}