python mapreduce-平均

Question

Python代码：

#!/usr/bin/python
#Reducer.py
import sys

age_balance = {}

#Partitoner
for line in sys.stdin:
    line = line.strip()
    age, balance = line.split('\t')

    if age in age_balance:
        age_balance[age].append(int(balance))
    else:
        age_balance[age] = []
        age_balance[age].append(int(balance))

#Reducer
for age in age_balance.keys():
    ave_age = sum(age_balance[age])*1.0 / len(age_balance[age])
    print '%s\t%s'% (age, ave_age)

嗨，我收到一个错误： 文件“ C：\ Code \ study \ reducer.py”，第16行，在age_balance [balance] .append（int（age））中ValueError：int（）的无效文字，基数为10：““ age”' 该过程试图写入不存在的管道。

This is a sample of the data im trying to get average of :