@panda88 比如下面这种用法：
```
def handle_data(context, data):
security_stoploss(context,loss=0.1)
## 个股止损
def security_stoploss(context,loss=0.1):
if len(context.portfolio.positions)>0:
for stock in context.portfolio.positions.keys():
avg_cost = context.portfolio.positions[stock].avg_cost
current_price = context.portfolio.positions[stock].price
if 1 - current_price/avg_cost >= loss:
log.info(str(stock) + ' 跌幅达个股止损线，平仓止损！')
order_target_value(stock, 0)
```
2017-03-06
雪球
