Python获得当前日历季度的第一天和最后一天

Question

我已经建立了一个功能,以获得当前季度的第一天和最后一天,但它有点长.我想知道,有没有更简洁的方法来完成这个？

我知道它pandas有一个QuarterBegin()功能,但我无法以更简洁的方式实现它.

import datetime as dt
from dateutil.relativedelta import relativedelta     

def get_q(first=None,last=None):

    today = dt.date.today()

    qmonth = [1, 4, 7, 10]

    if first:
        for i,v in enumerate(qmonth):
            if (today.month-1)//3 == i:
                return dt.date(today.year,qmonth[i],1).strftime("%Y-%m-%d")

    if last:
        firstday = dt.datetime.strptime(get_q(first=True),"%Y-%m-%d") 
        lastday = firstday + relativedelta(months=3, days=-1)
        return lastday.strftime("%Y-%m-%d")

---

编辑:如果这更适合代码审查,请告诉我

Answer 1

为什么要自己滚？

import pandas as pd

quarter_start = pd.to_datetime(pd.datetime.today() - pd.tseries.offsets.QuarterBegin(startingMonth=1)).date()

Answer 2

为什么这么复杂:-)

from datetime import date
from calendar import monthrange

quarter = 2
year = 2016
first_month_of_quarter = 3 * quarter - 2
last_month_of_quarter = 3 * quarter
date_of_first_day_of_quarter = date(year, first_month_of_quarter, 1)
date_of_last_day_of_quarter = date(year, last_month_of_quarter, monthrange(year, last_month_of_quarter)[1])

Answer 3

你可以这样做：

import bisect
import datetime as dt

def get_quarter_begin():
    today = dt.date.today()

    qbegins = [dt.date(today.year, month, 1) for month in (1,4,7,10)]

    idx = bisect.bisect(qbegins, today)
    return str(qbegins[idx-1])

这解决了“第一种”情况；我将“最后一个”案例作为练习，但为了清晰起见，我建议将其保留为独立函数（对于您的原始版本，如果没有传递参数，会发生什么，这是非常奇怪的！）。

Answer 4

您不需要使用不必要的循环或大型库（例如 pandas）来执行此操作。您可以使用简单的整数除法/算术和日期时间库来完成此操作（尽管使用 dateutil 会产生更干净的代码）。

import datetime

def getQuarterStart(dt=datetime.date.today()):
    return datetime.date(dt.year, (dt.month - 1) // 3 * 3 + 1, 1)

# using just datetime
def getQuarterEnd1(dt=datetime.date.today()):
    nextQtYr = dt.year + (1 if dt.month>9 else 0)
    nextQtFirstMo = (dt.month - 1) // 3 * 3 + 4
    nextQtFirstMo = 1 if nextQtFirstMo==13 else nextQtFirstMo
    nextQtFirstDy = datetime.date(nextQtYr, nextQtFirstMo, 1)
    return nextQtFirstDy - datetime.timedelta(days=1)

# using dateutil
from dateutil.relativedelta import relativedelta

def getQuarterEnd2(dt=datetime.date.today()):
    quarterStart = getQuarterStart(dt)
    return quarterStart + relativedelta(months=3, days=-1)

输出：

>>> d1=datetime.date(2017,2,15)
>>> d2=datetime.date(2017,1,1)
>>> d3=datetime.date(2017,10,1)
>>> d4=datetime.date(2017,12,31)
>>> 
>>> getQuarterStart(d1)
datetime.date(2017, 1, 1)
>>> getQuarterStart(d2)
datetime.date(2017, 1, 1)
>>> getQuarterStart(d3)
datetime.date(2017, 10, 1)
>>> getQuarterStart(d4)
datetime.date(2017, 10, 1)
>>> getQuarterEnd1(d1)
datetime.date(2017, 3, 31)
>>> getQuarterEnd1(d2)
datetime.date(2017, 3, 31)
>>> getQuarterEnd1(d3)
datetime.date(2017, 12, 31)
>>> getQuarterEnd1(d4)
datetime.date(2017, 12, 31)
>>> getQuarterEnd2(d1)
datetime.date(2017, 3, 31)
>>> getQuarterEnd2(d2)
datetime.date(2017, 3, 31)
>>> getQuarterEnd2(d3)
datetime.date(2017, 12, 31)
>>> getQuarterEnd2(d4)
datetime.date(2017, 12, 31)