def under_cross(signal,source,follow):
''' 信号日低于或下叉。source一般为downlimit,follow为low
不仅仅给出下叉信号,而且还给出signal日follow是否低于source
信号日低于，则将屏蔽买入
下叉则是卖出
'''
sd = equals(cross(source,follow),-1)
indices = (signal > 0)
sd[indices] = greater_equals(source[indices],follow[indices])
return sd
def under_cross(signal, source, follow):
''' 信号日低于或下叉。source一般为downlimit,follow为low
不仅仅给出下叉信号,而且还给出signal日follow是否低于source
信号日低于，则将屏蔽买入
下叉则是卖出
'''
sd = equals(cross(source, follow), -1)
indices = (signal > 0)
sd[indices] = greater_equals(source[indices], follow[indices])
return sd
def closedayofweek(weekdays): #周收盘日
#特别特殊的情形下会不正确,如某周一交易日后，下一个交易日正好是下周二,则该周一不会被识别为周收盘日
#另，最后一个交易日也被识别为周收盘日
return greater(greater_equals(weekdays-rollx(weekdays,-1)) + equals(weekdays,5))
def closedayofweek(weekdays): #周收盘日
#特别特殊的情形下会不正确,如某周一交易日后，下一个交易日正好是下周二,则该周一不会被识别为周收盘日
#另，最后一个交易日也被识别为周收盘日
return greater(
greater_equals(weekdays - rollx(weekdays, -1)) + equals(weekdays, 5))
