转载：python 日期，季度，年份

 # 这个data_matrix[:,dimen] <= thresh_val 内标会返回data_matrix当中的值符合条件的，返回为True
 # ret_array 中就会返回 下标为True的值
 ret_array[data_matrix[:,dimen] <= thresh_val] = -1.0

 # https://www.cnblogs.com/prolifes/articles/5195528.html
 # 亲测季度可用

 #coding=utf-8
 import datetime
 from datetime import timedelta

 now = datetime.datetime.now()

 #今天
 today = now

 #昨天
 yesterday = now - timedelta(days=1)

 #明天
 tomorrow = now + timedelta(days=1)<br><br>#当前季度

 now_quarter = now.month / 3 if now.month % 3 == 0 else now.month / 3 + 1

 #本周第一天和最后一天
 this_week_start = now - timedelta(days=now.weekday())
 this_week_end = now + timedelta(days=6-now.weekday())

 #上周第一天和最后一天
 last_week_start = now - timedelta(days=now.weekday()+7)
 last_week_end = now - timedelta(days=now.weekday()+1)

 #本月第一天和最后一天
 this_month_start = datetime.datetime(now.year, now.month, 1)
 this_month_end = datetime.datetime(now.year, now.month + 1, 1) - timedelta(days=1)

 #上月第一天和最后一天
 last_month_end = this_month_start - timedelta(days=1)
 last_month_start = datetime.datetime(last_month_end.year, last_month_end.month, 1)

 #本季第一天和最后一天
 month = (now.month - 1) - (now.month - 1) % 3 + 1
 this_quarter_start = datetime.datetime(now.year, month, 1)
 this_quarter_end = datetime.datetime(now.year, month + 3, 1) - timedelta(days=1)

 #上季第一天和最后一天
 last_quarter_end = this_quarter_start - timedelta(days=1)
 last_quarter_start = datetime.datetime(last_quarter_end.year, last_quarter_end.month - 2, 1)

 #本年第一天和最后一天
 this_year_start = datetime.datetime(now.year, 1, 1)
 this_year_end = datetime.datetime(now.year + 1, 1, 1) - timedelta(days=1)

 #去年第一天和最后一天
 last_year_end = this_year_start - timedelta(days=1)
 last_year_start = datetime.datetime(last_year_end.year, 1, 1)