python - 按月过滤日期时间对象中的日期

Question

我有一个字典，其中键是 datetime.datetime，值是推文列表。所以它看起来像这样:

{datetime.datetime(2017, 9, 30, 19, 55, 20) : ['this is some tweet text'],
 datetime.datetime(2017, 9, 30, 19, 55, 20) : ['this is another tweet']...

我正在尝试获取一年中每个月发送的推文数量。到目前为止我已经...

startDate = 10
endDate= 11
start = True
while start:

    for k,v in tweetDict.items():
        endDate-=1
        startDate-=1

        datetimeStart = datetime(2017, startDate, 1)
        datetimeEnd = datetime(2017,endDate, 1)

        print(datetimeStart, datetimeEnd)

        if datetimeStart < k < datetimeEnd:
            print(v)
        if endDate == 2:
            start = False
            break

只打印(我知道打印语句)...

2017-08-01 00:00:00 2017-09-01 00:00:00
2017-07-01 00:00:00 2017-08-01 00:00:00
2017-06-01 00:00:00 2017-07-01 00:00:00
2017-05-01 00:00:00 2017-06-01 00:00:00
2017-04-01 00:00:00 2017-05-01 00:00:00
2017-03-01 00:00:00 2017-04-01 00:00:00
2017-02-01 00:00:00 2017-03-01 00:00:00
2017-01-01 00:00:00 2017-02-01 00:00:00

而不是实际的推文本身。我期待的是……

2017-08-01 00:00:00 2017-09-01 00:00:00
['heres a tweet']
['theres a tweet']
2017-07-01 00:00:00 2017-08-01 00:00:00
['there only 1 tweet for this month']....

我有点卡住了，我该如何实现？

Answer 1

你可以 group by月份而不是尝试减去/比较不同的月份:

>>> d = {datetime.datetime(2017, 9, 30, 19, 55, 20): ['this is some tweet text'],
         datetime.datetime(2017, 9, 30, 20, 55, 20): ['this is another tweet'],
         datetime.datetime(2017, 10, 30, 19, 55, 20): ['this is an october tweet'],}
>>> from itertools import groupby
>>> for month, group in groupby(d.items(), lambda (k, v): k.month):
...     print(month)
...     for dt, tweet in group:
...         print(dt, tweet)
...         
10
2017-10-30 19:55:20 ['this is an october tweet']
9
2017-09-30 19:55:20 ['this is some tweet text']
2017-09-30 20:55:20 ['this is another tweet']
>>> 

当然，您可以以更好的格式打印它等等(需要内部连接，因为每个键似乎都是一个列表):

>>> for month, group in groupby(d.items(), lambda (k, v): k.month):
...     tweets = list(group)
...     print("%d tweet(s) in month %d" % (len(tweets), month))
...     print('\n'.join(','.join(tweet) for (dt, tweet) in tweets))
...     
1 tweet(s) in month 10
this is an october tweet
2 tweet(s) in month 9
this is some tweet text
this is another tweet
>>>