将字符串'yyyy-mm-dd'转换为日期时间python

converting string 'yyyy-mm-dd' into datetime python

提问by Udaya Tenneti

I have a raw input from the user such as "2015-01-30"...for the query I am using, the date has to be inputed as a string as such "yyyy-mm-dd".

我有来自用户的原始输入，例如“2015-01-30”...对于我正在使用的查询，日期必须作为字符串输入，例如“yyyy-mm-dd”。

I would like to increment the date by 1 month at end of my loop s.t "2015-01-30" becomes "2015-02-27" (ideally the last business day of the next month). I was hoping someone could help me; I am using PYTHON, the reason I want to convert to datetime is I found a function to add 1 month.

我想在循环结束时将日期增加 1 个月，“2015-01-30”变为“2015-02-27”（最好是下个月的最后一个工作日）。我希望有人能帮助我；我正在使用 PYTHON，我想转换为日期时间的原因是我找到了一个添加 1 个月的函数。

Ideally my two questions to be answered are (in Python):

理想情况下，我要回答的两个问题是（在 Python 中）：

1) how to convert string "yyyy-mm-dd" into a python datetime and convert back into string after applying a timedelta function

1）如何将字符串“yyyy-mm-dd”转换为python日期时间并在应用timedelta函数后转换回字符串

2) AND/or how to add 1 month to string "yyyy-mm-dd"

2）和/或如何将 1 个月添加到字符串“yyyy-mm-dd”

采纳答案by A.J. Uppal

You can use a one-liner, that takes the datetime, adds a month (using a defined function), and converts back to a string:

您可以使用单行，它接受datetime，添加一个月（使用定义的函数），然后转换回字符串：

x = add_months(datetime.datetime(*[int(item) for item in x.split('-')]), 1).strftime("%Y-%m-%d")

---

---

>>> import datetime, calendar
>>> x = "2015-01-30"
>>> x = add_months(datetime.datetime(*[int(item) for item in x.split('-')]), 1).strftime("%Y-%m-%d")
>>> x
'2015-02-28'
>>> 

add_months:

add_months：

def add_months(sourcedate,months):
    month = sourcedate.month - 1 + months
    year = sourcedate.year + month / 12
    month = month % 12 + 1
    day = min(sourcedate.day,calendar.monthrange(year,month)[1])
    return datetime.date(year,month,day)

回答by Tenzin

Maybe these examples will help you get an idea:

也许这些例子会帮助你得到一个想法：

from dateutil.relativedelta import relativedelta
import datetime

date1 = datetime.datetime.strptime("2015-01-30", "%Y-%m-%d").strftime("%d-%m-%Y")
print(date1)

today = datetime.date.today()
print(today)
addMonths = relativedelta(months=3)
future = today + addMonths
print(future) 

If you import datetime it will give you more options in managing date and time variables.
In my example above I have some example code that will show you how it works.

如果您导入 datetime，它将为您提供更多管理日期和时间变量的选项。
在我上面的示例中，我有一些示例代码将向您展示它是如何工作的。

It is also very usefull if you would for example would like to add a x number of days, months or years to a certain date.

例如，如果您想将天数、月数或年数添加到某个日期，这也非常有用。

Edit: To answer you question below this post I would suggest you to look at "calendar"

编辑：要回答您在这篇文章下方的问题，我建议您查看“日历”

For example:

例如：

import calendar 
january2012 = calendar.monthrange(2002,1)
print(january2012)
february2008 = calendar.monthrange(2008,2)
print(february2008)

This return you the first workday of the month, and the number of days of the month.
With that you can calculate what was the last workday of the month.
Here is more information about it: Link
Also have a loook here, looks what you might could use: Link

这将返回该月的第一个工作日以及该月的天数。
有了它，您可以计算出当月的最后一个工作日。
这是有关它的更多信息：链接
也看看这里，看看你可能会使用什么：链接

回答by chucksmash

To convert a string of that format into a Python date object:

将该格式的字符串转换为 Python 日期对象：

In [1]: import datetime

In [2]: t = "2015-01-30"

In [3]: d = datetime.date(*(int(s) for s in t.split('-')))

In [4]: d
Out[4]: datetime.date(2015, 1, 30)

To move forward to the last day of next month:

前进到下个月的最后一天：

In [4]: d
Out[4]: datetime.date(2015, 1, 30)

In [5]: new_month = (d.month + 1) if d.month != 12 else 1

In [6]: new_year = d.year if d.month != 12 else d.year + 1

In [7]: import calendar

In [8]: new_day = calendar.monthrange(new_year, new_month)[1]

In [9]: d = d.replace(year=new_year,month=new_month,day=new_day)

In [10]: d
Out[10]: datetime.date(2015, 2, 28)

And this datetime.dateobject can be easily converted to a 'YYYY-MM-DD' string:

这个datetime.date对象可以很容易地转换为 'YYYY-MM-DD' 字符串：

In [11]: str(d)
Out[11]: '2015-02-28'

EDIT:

编辑：

To get the last business day (i.e. Monday-Friday) of the month:

获取当月的最后一个工作日（即周一至周五）：

In [8]: new_day = calendar.monthrange(new_year, new_month)[1]

In [9]: d = d.replace(year=new_year,month=new_month,day=new_day)

In [10]: day_of_the_week = d.isoweekday()

In [11]: if day_of_the_week > 5:
   ....:     adj_new_day = new_day - (day_of_the_week - 5)
   ....:     d = d.replace(day=adj_new_day)
   ....:

In [11]: d
Out[11]: datetime.date(2015, 2, 27)

回答by jfs

converting string 'yyyy-mm-dd' into datetime/datepython

将字符串 'yyyy-mm-dd' 转换为datetime/ datepython

from datetime import date

date_string = '2015-01-30'
now = date(*map(int, date_string.split('-')))
# or now = datetime.strptime(date_string, '%Y-%m-%d').date()

the last business day of the next month

下个月的最后一个工作日

from datetime import timedelta

DAY = timedelta(1)
last_bday = (now.replace(day=1) + 2*31*DAY).replace(day=1) - DAY
while last_bday.weekday() > 4: # Sat, Sun
    last_bday -= DAY
print(last_bday)
# -> 2015-02-27

It doesn't take into account holidays.

它不考虑假期。