[Python] よく使いそうな日付処理まとめ

Pythonの日付処理をまとめておく。（必要に応じて追記）

from datetime import datetime,timedelta
now = datetime.utcnow() + timedelta(hours=9)

▼昨日

last_day = now + timedelta(days=-1)
print(last_day.strftime("%Y-%m-%d"))

▼先月1日

last_month = datetime(now.year, now.month, 1) + timedelta(days=-1)
print(last_month.strftime("%Y-%m-01"))

▼昨年同月1日

last_year_same_month = datetime(now.year-1, now.month, 1)
print(last_year_same_month.strftime("%Y-%m-01"))