计算/导出连续日期跨度中的第一个开始日期

import datetime

def calculate_start_date(start_date, end_date):
    date_format = "%Y-%m-%d"  # 日期格式
    start_date_obj = datetime.datetime.strptime(start_date, date_format)
    end_date_obj = datetime.datetime.strptime(end_date, date_format)
    delta = end_date_obj - start_date_obj
    start_date = start_date_obj - datetime.timedelta(days=delta.days)
    return start_date.strftime(date_format)

# 示例调用
start_date = "2022-01-01"
end_date = "2022-01-31"
result = calculate_start_date(start_date, end_date)
print(result)