从开始时间循环遍历Python月份

Question

我想从一个指定的开始时间开始，循环遍历每个月，并打印出每个月的第一天和最后一天。我可以手动记录现在是哪个月和哪一年，然后用calendar.monthrange(year, month)来获取这个月有多少天……但这样做真的是最好的方法吗？

from datetime import date
start_date = date(2010, 8, 1)
end_date = date.today()
# I want to loop through each month and print the first and last day of the month
# 2010, 8, 1 to 2010, 8, 31
# 2010, 9, 1 to 2010, 9, 30
# ....
# 2011, 3, 1 to 2011, 3, 31
# 2011, 4, 1, to 2011, 4, 12 (ends early because it is today)

Answer 1

dateutil模块确实支持这样的操作，具体可以查看这里：http://niemeyer.net/python-dateutil#head-470fa22b2db72000d7abe698a5783a46b0731b57

Answer 2

1. 从开始日期的第一天开始。
2. 计算这个月有多少天，然后找到下个月的第一天。
3. 打印出开始日期和（下个月的第一天减去一天）。

这样做是有效的：

#!/usr/bin/python
from datetime import date, timedelta
import calendar
start_date = date(2001,8,1)
end_date = date.today()
while True:
    if start_date > end_date:
        break
    days_in_month = calendar.monthrange(start_date.year, start_date.month)[1]  # Calculate days in month for start_date
    new_ts = calendar.timegm(start_date.timetuple()) + (days_in_month * 24 * 60 * 60)  # Get timestamp for start of next month
    new_start_date = date(1,1,1).fromtimestamp(new_ts) # Convert timestamp to date object
    print start_date, new_start_date - timedelta(1)
    start_date = new_start_date

Answer 3

要找出一个月的最后一天，你可以用下个月的第一天减去一天。比如说：

def enumerate_month_dates(start_date, end_date):
    current = start_date
    while current <= end_date:
        if current.month >= 12:
            next = datetime.date(current.year + 1, 1, 1)
        else:
            next = datetime.date(current.year, current.month + 1, 1)
        last = min(next - datetime.timedelta(1), end_date)
        yield current, last
        current = next