[Fix]Close #638

vnpy/trader/vtFunction.py

@@ -8,18 +8,18 @@ import os
 import decimal
 import json
 from datetime import datetime
+from math import isnan
 
 
 MAX_NUMBER = 10000000000000
 MAX_DECIMAL = 4
 
-
 #----------------------------------------------------------------------
 def safeUnicode(value):
     """检查接口数据潜在的错误，保证转化为的字符串正确"""
     # 检查是数字接近0时会出现的浮点数上限
     if type(value) is int or type(value) is float:
-        if value > MAX_NUMBER:
+        if value > MAX_NUMBER or isnan(value):
             value = 0
     
     # 检查防止小数点位过多