python 年月日を計算

年月日を計算

• relativedelta

import datetime
from dateutil.relativedelta import relativedelta

dt = datetime.datetime(2017,1,1)
print(dt, '(基準年月日)')

# 3年後
dt_plus_year = dt + relativedelta(years=3, months=6, days=23)
print(dt_plus_year, '(3年6ヶ月23日後)')

# 1ヶ月前
dt_minus_month = dt + relativedelta(months=-1)
print(dt_minus_month, '(1ヶ月前)')

# 90日前
dt_minus_day = dt + relativedelta(days=-90)
print(dt_minus_day, '(90日前)', type(dt_minus_day))

[out]

2017-01-01 00:00:00 (基準年月日)
2020-07-24 00:00:00 (3年6ヶ月23日後)
2016-12-01 00:00:00 (1ヶ月前)
2016-10-03 00:00:00 (90日前) <class 'datetime.datetime'>

• dateutil 公式サイト
  • https://dateutil.readthedocs.io/en/stable/