问题描述
import datetime as DT
import itertools
start_date=DT.date(2008,5,5)
def mkdate(datestring):
return DT.datetime.strptime(datestring, "%Y-%m-%d").date()
def fortnight(date):
return (date-start_date).days //14
raw = ("2010-08-01",
"2010-06-25",
"2010-07-01",
"2010-07-08")
transactions=[(date,"Some data") for date in map(mkdate,raw)]
transactions.sort(key=lambda (date,data):date)
for key,grp in itertools.groupby(transactions,key=lambda (date,data):fortnight(date)):
print(key,list(grp))
产量
# (55, [(datetime.date(2010, 6, 25), 'Some data')])
# (56, [(datetime.date(2010, 7, 1), 'Some data'), (datetime.date(2010, 7, 8), 'Some data')])
# (58, [(datetime.date(2010, 8, 1), 'Some data')])
请注意,2010-6-25是2008-5-5的第55个两周,而2010-7-1是第56个。如果您希望将它们组合在一起,只需进行更改start_date
(更改为类似于2008-5-16的内容)。
PS。上面使用的关键工具是itertools.groupby
,此处将对其进行详细说明。
Edit: The lambda
s are simply a way to make “anonymous”
functions. (They
are anonymous in the sense that they are not given names like functions
defined by def
). Anywhere you see a lambda, it is also possible to use adef
to create an equivalent function. For example, you Could do this:
import operator
transactions.sort(key=operator.itemgetter(0))
def transaction_fortnight(transaction):
date,data=transaction
return fortnight(date)
for key,grp in itertools.groupby(transactions,key=transaction_fortnight):
print(key,list(grp))
解决方法
我想将日历分为两周,从2008-May-5
或任何任意的起点开始。
因此,我从几个日期对象开始:
import datetime as DT
raw = ("2010-08-01","2010-06-25","2010-07-01","2010-07-08")
transactions = [(DT.datetime.strptime(datestring,"%Y-%m-%d").date(),"Some data here") for datestring in raw]
transactions.sort()
通过手动分析日期,我完全能够弄清楚哪些日期属于同一两周间隔。我想得到与这个相似的分组:
# Fortnight interval 1
(datetime.date(2010,6,25),'Some data here')
(datetime.date(2010,7,1),8),'Some data here')
# Fortnight interval 2
(datetime.date(2010,8,'Some data here')