如何在 PYTHON 中找到当前月份（excel 版本的 EOMONTH）的最后一天？

Question

我的 df 当前仅包含日期列

date
28/09/1995
30/10/1993
26/02/2021
04/04/2020

我想创建 2 个名为“月底”的新列，它给出了该月的最后一天和“季度末”，它给出了该季度的最后一天

date         end of month  end of quarter
28/09/1995   30/09/1995    30/09/1995
30/10/1993   31/10/1993    31/12/1993
26/02/2021   28/02/2021    31/03/2021
04/04/2020   30/04/2020    30/06/2020

请帮我解决这个问题

Answer 1

试试这个：

import pandas as pd

df = pd.DataFrame({'date':['28/09/1995', '30/10/1993', '26/02/2021', '04/04/2020']})
df['date'] = pd.to_datetime(df['date'], dayfirst=True)
df['end of month'] = df['date'] + pd.offsets.MonthEnd(1)
df['end of quarter'] = df['date'] + pd.offsets.QuarterEnd(1)

        date end of month end of quarter
0 1995-09-28   1995-09-30     1995-09-30
1 1993-10-30   1993-10-31     1993-12-31
2 2021-02-26   2021-02-28     2021-03-31
3 2020-04-04   2020-04-30     2020-06-30

Answer 2

仅使用 Python 标准库：

from datetime import datetime, timedelta

def date_to_endofmonth(dt: datetime) -> datetime:
    # reset day to first day of month, add one month and subtract 1 day:
    return (datetime(dt.year + ((dt.month+1) // 12), ((dt.month+1) % 12) or 12, 1)
            - timedelta(1))

def date_to_endofquarter(dt: datetime) -> datetime:
    # from given month, calculate quarter end month, then hand over to date_to_endofmonth
    return date_to_endofmonth(datetime(dt.year, ((dt.month - 1) // 3) * 3 + 3, dt.day))

例如：

for s in "28/09/1995", "30/12/1993", "26/02/2021", "04/04/2020":
    dt = datetime.strptime(s, "%d/%m/%Y")
    print(s, '->', date_to_endofmonth(dt).date(), '->', date_to_endofquarter(dt).date())

28/09/1995 -> 1995-09-30 -> 1995-09-30
30/12/1993 -> 1993-12-31 -> 1993-12-31
26/02/2021 -> 2021-02-28 -> 2021-03-31
04/04/2020 -> 2020-04-30 -> 2020-06-30

如何在 PYTHON 中找到当前月份（excel 版本的 EOMONTH）的最后一天？

How to find the last date of the month from current month (excel version of EOMONTH) in PYTHON?

python

datetime

date

data-manipulation

pandas