def estimate(self, deal, current_date, history_length):
""" 使用当天deal历史销量拟合直线估计当天销量
"""
daily_volumes = filter(lambda x:x[1] >= 0, deal['all_daily_volumes'].items())
daily_volumes.sort(key = lambda x:x[0])
earlist_date = current_date - datetime.timedelta(days = history_length)
history_records = [item for item in daily_volumes if str(earlist_date) <= item[0] < str(current_date)]
#logging.debug("DAILY_VOLUMES: %s; EARLY: %s; RECORD: %s" % (daily_volumes, earlist_date, history_records))
if len(history_records) < 2:
# 想画条线至少需要两个点
return None
xs = [(datetime.datetime.strptime(item[0], '%Y-%m-%d').date() - earlist_date).days for item in history_records]
ys = [item[1] for item in history_records]
x = (current_date - earlist_date).days
linear_fit_volume = max(Utils.get_linear_estimate(xs, ys, x), 1)
#logging.debug("X: %s, Y: %s, x: %s, fit: %s" % (xs, ys, x, linear_fit_volume))
return linear_fit_volume
