从一年中获得一年中的一周

import datetime

# 获取当前日期
today = datetime.date.today()

# 计算一年中的第几周
week_number = today.isocalendar()[1]

# 计算一年中的第一周开始日期
first_week_start = datetime.date(today.year, 1, 1)
first_week_end = datetime.date(today.year, 1, 7)

# 计算一年中的第一周结束日期
if first_week_end.isoweekday() == 7:
    first_week_end = first_week_end - datetime.timedelta(days=7)

# 计算当前日期是一年中的第几周
if today< first_week_end:
    week_number = 1

# 计算当前日期是一年中的第几天
day_number = (today - first_week_start).days + 1

# 计算一年中的第一周是从哪一天开始的
first_week_start_day = first_week_start.isoweekday()

# 计算一年中的第一周是从哪一天结束的
first_week_end_day = first_week_end.isoweekday()

# 计算一年中的第一周有多少天
first_week_days = (first_week_end - first_week_start).days + 1

# 输出结果
print("今天是{}年的第{}天".format(today.year, day_number))
print("今天是{}年的第{}周".format(today.year, week_number))
print("{}年的第{}周从{}开始，到{}结束，共{}天".format(today.year, week_number, first_week_start, first_week_end, first_week_days))