monthscalculation.py

import datetime
import calendar as c


def calmonths(startdate, enddate):
    # 计算两个日期相隔月差
    samemonthdate = None
    try:
        samemonthdate = datetime.date(
            enddate.year, enddate.month, startdate.day)
    except Exception as e:
        print(e)
        samemonthdate = datetime.date(
            enddate.year, enddate.month, c.monthrange(enddate.year, enddate.month)[1])

    holdmonths = 0
    decimalmonth = 0.0
    if samemonthdate > enddate:
        premanthdate = None
        try:
            premanthdate = datetime.date(
                enddate.year, enddate.month - 1, startdate.day)
        except Exception as e:
            print(e)
            premanthdate = datetime.date(
                enddate.year, enddate.month - 1, c.monthrange(enddate.year, enddate.month - 1)[1])
        currmonthdays = (samemonthdate - premanthdate).days
        holdmonths = (premanthdate.year - startdate.year) * \
            12 + premanthdate.month - startdate.month
        decimalmonth = (enddate - premanthdate).days / currmonthdays

    elif samemonthdate < enddate:
        nextmonthdate = None
        if enddate.month == 12:
            endyear =  enddate.year + 1
            endmonth = 1
        else:
            endyear =  enddate.year
            endmonth = enddate.month + 1         
        try:
            nextmonthdate = datetime.date(
                enddate.year, enddate.month + 1, startdate.day)
        except Exception as e:
            nextmonthdate = datetime.date(
                endyear, endmonth, c.monthrange(endyear, endmonth)[1])
        currmonthdays = (nextmonthdate - samemonthdate).days
        holdmonths = (samemonthdate.year - startdate.year) * \
            12 + samemonthdate.month - startdate.month
        decimalmonth = (enddate - samemonthdate).days / currmonthdays

    else:
        holdmonths = (enddate.year - startdate.year) * \
            12 + enddate.month - startdate.month

    return holdmonths, decimalmonth


if __name__ == '__main__':
    d1 = datetime.date(2021, 1, 1)
    d2 = datetime.date(2022, 1, 1)
    months = calmonths(d1, d2)
    print(f"months={months}")