我在python脚本中遵循了zeropad.py下面的步骤

!/usr/bin/python

from org.apache.pig.scripting import *

@outputSchema('time:int')

def zero():
    time.zfill(4)

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使用org.apache.pig.scripting.jython.jythonscriptengine作为myfuncs注册'zeropad.py'；

Airlines_data_schema = LOAD 'AirlinesData_sample-1.csv' USING PigStorage('\t') AS (Year,Month,DayofMonth,DayofWeek,DepTime_actual:int,CRSDeptime:int,Arrtime_actual:int,CRSArrtime:int,UniqueCarrier,FlightNum,TailNum_Plane,ActualElapsedTime,CRSElapsedTime,Airtime,Arrdelay,Depdelay,Origin,Dest,Distance,Taxiin,Taxiout,Cancelled,CancellationCode,Diverted,CarrierDelay,WeatherDelay,NASDelay,SecurityDelay,LateAircraftDelay);

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airlines_new = FOREACH Airlines_data_schema GENERATE Year,Month,DayofMonth,DayofWeek,myfuncs.zero.DepTime_actual AS DepTime_actual_new,myfuncs.zero.CRSDeptime AS CRSDeptime_new,myfuncs.zero.Arrtime_actual AS Arrtime_actual_new,myfuncs.zero.CRSArrtime AS CRSArrtime_new,UniqueCarrier,FlightNum,TailNum_Plane,ActualElapsedTime,CRSElapsedTime,Airtime,Arrdelay,Depdelay,Origin,Dest,Distance,Taxiin,Taxiout,Cancelled,CancellationCode,Diverted,CarrierDelay,WeatherDelay,NASDelay,SecurityDelay,LateAircraftDelay ;

我得到以下错误

2017-02-26 19:37:19,606 [main] ERROR org.apache.pig.tools.grunt.Grunt - ERROR 1025:

字段投影无效。架构中不存在投影字段[myfuncs]：year:bytearray,month:bytearray，第ayofmonth:bytearray,dayofweek:bytearray，部门时间_actual:int，c级rsdeptime:int，到达时间_actual:int，c级rsarrtime:int，统一uecarrier:bytearray,flightnum:bytearray，尾数_plane:bytearray，实际值apsedtime:bytearray，crsel公司apsedtime:bytearray,airtime:bytearray,arrdelay:bytearray,depdelay:bytearray,origin:bytearray,dest:bytearray,distance:bytearray,taxiin:bytearray,taxiout:bytearray,cancelled:bytearray，取消ationcode:bytearray,diverted:bytearray，汽车rierdelay:bytearray，wea公司therdelay:bytearray,nasdelay:bytearray，塞库ritydelay:bytearray，lateairc公司raftdelay:bytearray.
想知道为什么我不能使用python函数来操作我的列值