使用日期时间填写列表中缺失月份的最佳方法是什么？

Question

我正在尝试制作的程序的主要目的是能够填写（插入）具有价格和日期时间的对象列表，如果缺少月份，如果有，插入重复对象，但月份正确，该特定月份的最后一天价格相同（无变化）

这是一个例子。 假设列表dateprices 在程序的其他地方动态填充了对象。每个项目 (datePriceObj) 都有变量：date 是日期时间对象，price 是该日期的价格（假设它是亚马逊上产品的价值或其他东西，没关系.)

我想要达到的效果如下所示：

创建下面对象的类

class DatePriceCreator():
    def __init__(self, datetimeObj, priceFloat):
        self.date = datetimeObj
        self.price = priceFloat

我目前所拥有的，需要更改以便正确填写月份：

datePrices = [datePriceObj, datePriceObj, datePriceObj, datePriceObj, datePriceObj]


# datePrices[0].date is equal to 25th October 2019 (this is a datetime object)
# datePrices[1].date is equal to 23rd November 2019 (this is a datetime object)
# datePrices[2].date is equal to 26th February 2020 (this is a datetime object)
# datePrices[3].date is is equal to 26th March 2020 (this is a datetime object)
# datePrices[4].date is equal to 15th May 2020 (this is a datetime object)

# datePrices[0].price is equal to 1000.0 (this is a float)
# datePrices[1].price is equal to 1056.0 (this is a float)
# datePrices[2].price is equal to 1700.0 (this is a float)
# datePrices[3].price is equal to 1750.0 (this is a float)
# datePrices[4].price is equal to 2007.0 (this is a float)

预期输出：

# Expected Output:
datePrices = [datePriceObj, datePriceObj, datePriceObj, datePriceObj. datePriceObj, datePriceObj, datePriceObj, datePriceObj]

# datePrices[0].date is equal to 25th October 2019 (this is a datetime object)
# datePrices[1].date is equal to 23rd November 2019 (this is a datetime object)
# datePrices[2].date is equal to 31st December 2019 (this is a datetime object)
# datePrices[3].date is equal to 31st January 2020 (this is a datetime object)
# datePrices[4].date is equal to 26th February 2020 (this is a datetime object)
# datePrices[5].date is is equal to 26th March 2020 (this is a datetime object)
# datePrices[6].date is is equal to 30th April 2020 (this is a datetime object)
# datePrices[7].date is equal to 15th May 2020 (this is a datetime object)

# datePrices[0].price is equal to 1000.0 (this is a float)
# datePrices[1].price is equal to 1056.0 (this is a float)
# datePrices[2].price is equal to 1056.0 (this is a float)
# datePrices[3].price is equal to 1056.0 (this is a float)
# datePrices[4].price is equal to 1700.0 (this is a float)
# datePrices[5].price is equal to 1750.0 (this is a float)
# datePrices[6].price is equal to 1750.0 (this is a float)
# datePrices[7].price is equal to 2007.0 (this is a float)

正如您在预期输出中看到的那样，新对象已填充到列表中，这些新对象包含填充月份的日期、该月的最后一天以及价格和之前的一样。

我面临的问题是如何做到这一点，所以无论年份是什么，它总是有下个月。这显示在 datePrices[2] 和 datePrices[3] 的预期输出中，它识别出年份已更改。我不知道该怎么做。可能使用某种 while 循环来继续创建对象并插入到列表中，直到 datePrices[x+1].date.month - 1 等于 datePrices[x].date.month，但这只有在 datePrices[x].date.month is <= 11 时才有效。如果是12，则下个月必须是13，但没有第13个月。

我是这方面的初学者，想知道在不使用太多条件的情况下最有效的解决方案是什么，除非绝对必要。

Answer 1

创建一个方法，为一个日期添加足够的天数，使其在下个月：

import datetime
import random 

class DatePriceCreator():
    def __init__(self, datetimeObj, priceFloat):
        self.date = datetimeObj
        self.price = priceFloat
    def __str__(self):
        return f"{self.date} with {self.price}"

def next_month_last_day(d):
    c = d
    c += datetime.timedelta( 28-d.day)
    while c.month != ((d.month+1)%12+1):
        c += datetime.timedelta(1)
    c -= datetime.timedelta(1)
    return c

price = DatePriceCreator(datetime.datetime(2020,1,1), 47.22)

while price.date.year < 2021 or price.date.month < 3:
    print(price)
    next_m = next_month_last_day(price.date)
    price.date = next_m

print(price)

输出：

2020-01-01 00:00:00 with 47.22
2020-02-29 00:00:00 with 47.22
2020-03-31 00:00:00 with 47.22
2020-04-30 00:00:00 with 47.22
2020-05-31 00:00:00 with 47.22
2020-06-30 00:00:00 with 47.22
2020-07-31 00:00:00 with 47.22
2020-08-31 00:00:00 with 47.22
2020-09-30 00:00:00 with 47.22
2020-10-31 00:00:00 with 47.22
2020-11-30 00:00:00 with 47.22
2020-12-31 00:00:00 with 47.22
2021-01-31 00:00:00 with 47.22
2021-02-28 00:00:00 with 47.22
2021-03-31 00:00:00 with 47.22 

将其应用于您获得的任何日期间隔。