python 日期函数的使用

计算一段时间内，周六出现的次数。

如果是周六，则 5 == dt_start.weekday()

这里用到了2个主要的日期函数

datetime_to_date_int，

date_int_to_datetime

import datetime
def datetime_to_date_int(dt):
    if isinstance(dt, datetime.datetime):
        dt = dt.date()
        return dt.year * 10000 + dt.month * 100 + dt.day
    elif isinstance(dt, datetime.date):
        return dt.year * 10000 + dt.month * 100 + dt.day
    raise RuntimeError('unsupported parameter type:', type(dt))

def date_int_to_datetime(dt):
    if isinstance(dt,datetime.datetime):
        return dt
    if dt is None:
        return datetime.datetime.now()
    if dt == 0:
        return datetime.datetime.now()
    if isinstance(dt, str):
        if '-' in dt:
            return datetime.datetime.strptime(dt, "%Y-%m-%d")
        else:
            return datetime.datetime.strptime(dt, "%Y%m%d")
    y = int(dt / 10000)
    m = int(dt / 100 - y * 100)
    return datetime.datetime(y, m, int(dt - y * 10000 - m * 100))

dt_start  = date_int_to_datetime(20230101)
dt_end = date_int_to_datetime(20801231)
month_day_map:dict = {}
while dt_start <= dt_end:
    tradedate = datetime_to_date_int(dt_start)
    if 5 == dt_start.weekday():
        month_day = tradedate % 1000
        if month_day>528 and month_day<925:
            str_key = str(month_day)
            if month_day_map.get(str_key)!= None :
                month_day_map[str_key] += 1
            else:
                month_day_map[str_key] = 1
    dt_start = dt_start + datetime.timedelta(days=1)
sort_map = sorted(month_day_map.items(), key = lambda x:x[1], reverse = True)
print("sort_map:",sort_map)