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python(pyenv)インストールメモ

datetime

# -*- coding:utf-8 -*-
import datetime
from datetime import date,timedelta

# 現在日時
d = datetime.date.today() # 2019-08-01
print(d.strftime("%Y%m%d")) # 20190801
 
# 基準日
d = date(2019, 8, 01) # 2019-08-01
# 前日
yesterday = d - timedelta(days=1) # 2019-07-31
# 20日前
before_20_days = d - timedelta(days=1) * 20 # 2019-07-12
# 40日前
before_40_days = d - timedelta(days=40) # 2019-06-22
# 2週間前
two_weeks_ago = d + timedelta(weeks=-2) # 2019-07-18

早見表

Code	Meaning	Example
%a	Weekday as locale’s abbreviated name.	Mon
%A	Weekday as locale’s full name.	Monday
%w	Weekday as a decimal number, where 0 is Sunday and 6 is Saturday.	1
%d	Day of the month as a zero-padded decimal number.	30
%-d	Day of the month as a decimal number. (Platform specific)	30
%b	Month as locale’s abbreviated name.	Sep
%B	Month as locale’s full name.	September
%m	Month as a zero-padded decimal number.	9
%-m	Month as a decimal number. (Platform specific)	9
%y	Year without century as a zero-padded decimal number.	13
%Y	Year with century as a decimal number.	2013
%H	Hour (24-hour clock) as a zero-padded decimal number.	7
%-H	Hour (24-hour clock) as a decimal number. (Platform specific)	7
%I	Hour (12-hour clock) as a zero-padded decimal number.	7
%-I	Hour (12-hour clock) as a decimal number. (Platform specific)	7
%p	Locale’s equivalent of either AM or PM.	AM
%M	Minute as a zero-padded decimal number.	6
%-M	Minute as a decimal number. (Platform specific)	6
%S	Second as a zero-padded decimal number.	5
%-S	Second as a decimal number. (Platform specific)	5
%f	Microsecond as a decimal number, zero-padded on the left.	0
%z	UTC offset in the form +HHMM or -HHMM (empty string if the the object is naive).
%Z	Time zone name (empty string if the object is naive).
%j	Day of the year as a zero-padded decimal number.	273
%-j	Day of the year as a decimal number. (Platform specific)	273
%U	Week number of the year (Sunday as the first day of the week) as a zero padded decimal number. All days in a new year preceding the first Sunday are considered to be in week 0.	39
%W	Week number of the year (Monday as the first day of the week) as a decimal number. All days in a new year preceding the first Monday are considered to be in week 0.	39
%c	Locale’s appropriate date and time representation.	Mon Sep 30 07:06:05 2013
%x	Locale’s appropriate date representation.	9/30/2013
%X	Locale’s appropriate time representation.	7:06:05
%%	A literal '%' character.	%

[参考]
http://strftime.org/
http://docs.python.jp/2/library/datetime.html