python 날짜 및 시간 계산은 python 표준 라이브러리 datetime, 확장 라이브러리 dateutil 2개의 라이브러리가 있으며 단위의 차이가 있다.

  • datetime : 마이크로초, 밀리초, 초, 분, 시, 일, 주 단위 사용
  • dateutil : 마이크로초, 초, 분, 시, 일, 주, 월, 년 단위 사용

1. datetime 라이브러리

날짜와 시간을 조작하는 클래스를 제공하는 python 표준 라이브러리

1.1 사용예시

  • now : 현재 날짜 및 시간

    import datetime as dt

now = dt.datetime.now()

print(f"now = {now}")

    now = 2021-12-27 11:24:27.172476

  • microsecond

    print(f"microsecond before = {now - timedelta(microseconds=1)}")
print(f"microsecond next   = {now + timedelta(microseconds=1)}")

    microsecond before = 2021-12-26 22:08:42.685501
    microsecond next = 2021-12-26 22:08:42.685503

  • millisecond

    print(f"millisecond before = {now - timedelta(milliseconds=1)}")
print(f"millisecond next   = {now + timedelta(milliseconds=1)}")

    millisecond before = 2021-12-26 22:08:42.684502
    millisecond next = 2021-12-26 22:08:42.686502

  • second

    print(f"second before = {now - timedelta(seconds=1)}")
print(f"second next   = {now + timedelta(seconds=1)}")

    second before = 2021-12-26 22:08:41.685502
    second next = 2021-12-26 22:08:43.685502

  • minute

    print(f"minute before = {now - timedelta(minutes=1)}")
print(f"minute next   = {now + timedelta(minutes=1)}")

    minute before = 2021-12-26 22:07:42.685502
    minute next = 2021-12-26 22:09:42.685502

  • hour

    print(f"hour before = {now - timedelta(hours=1)}")
print(f"hour next   = {now + timedelta(hours=1)}")

    hour before = 2021-12-26 21:08:42.685502
    hour next = 2021-12-26 23:08:42.685502

  • day

    print(f"day before = {now - timedelta(days=1)}")
print(f"day next   = {now + timedelta(days=1)}")

    day before = 2021-12-25 22:08:42.685502
    day next = 2021-12-27 22:08:42.685502

  • week

    print(f"week before = {now - timedelta(weeks=1)}")
print(f"week next   = {now + timedelta(weeks=1)}")

    week before = 2021-12-19 22:08:42.685502
    week next = 2022-01-02 22:08:42.685502

  • 복합사용

    print(f"week before = {now - timedelta(days=1, hours=1, minutes=1)}")
print(f"week next   = {now + timedelta(days=1, hours=1, minutes=1)}")

    week before = 2021-12-25 21:07:42.685502
    week next = 2021-12-27 23:09:42.685502

2. dateutil 라이브러리

datetime 보다 확장된 기능을 가진 라이브러리

2.1. 라이브러리 설치

> pip install dateutil

2.2. 사용예시

  • now : 현재 날짜 및 시간

    from datetime import datetime
from dateutil.relativedelta import relativedelta

now = datetime.now()

print(f"now = {now}")

    now = 2021-12-26 22:23:22.916446

  • microsecond

    print(f"microsecond before = {now - relativedelta(microseconds=1)}")
print(f"microsecond next   = {now + relativedelta(microseconds=1)}")

    microsecond before = 2021-12-26 22:23:22.916445
    microsecond next = 2021-12-26 22:23:22.916447

  • second

    print(f"second before = {now - relativedelta(seconds=1)}")
print(f"second next   = {now + relativedelta(seconds=1)}")

    second before = 2021-12-26 22:23:21.916446
    second next = 2021-12-26 22:23:23.916446

  • minute

    print(f"minute before = {now - relativedelta(minutes=1)}")
print(f"minute next   = {now + relativedelta(minutes=1)}")

    minute before = 2021-12-26 22:22:22.916446
    minute next = 2021-12-26 22:24:22.916446

  • hour

    print(f"hour before = {now - relativedelta(hours=1)}")
print(f"hour next   = {now + relativedelta(hours=1)}")

    hour before = 2021-12-26 21:23:22.916446
    hour next = 2021-12-26 23:23:22.916446

  • day

    print(f"day before = {now - relativedelta(days=1)}")
print(f"day next   = {now + relativedelta(days=1)}")

    day before = 2021-12-25 22:23:22.916446
    day next = 2021-12-27 22:23:22.916446

  • week

    print(f"week before = {now - relativedelta(weeks=1)}")
print(f"week next   = {now + relativedelta(weeks=1)}")

    week before = 2021-12-19 22:23:22.916446
    week next = 2022-01-02 22:23:22.916446

  • month

    print(f"month before = {now - relativedelta(months=1)}")
print(f"month next   = {now + relativedelta(months=1)}")

    month before = 2021-11-26 22:23:22.916446
    month next = 2022-01-26 22:23:22.916446

  • year

    print(f"year before = {now - relativedelta(years=1)}")
print(f"year next   = {now + relativedelta(years=1)}")

    year before = 2020-12-26 22:23:22.916446
    year next = 2022-12-26 22:23:22.916446

3. 예시코드 Git

python-calculate-the-date-and-time

참고(Reference)