求和两列，计算 MapReduce 中的最大值、最小值和平均值

Question

我有一个mapper的示例代码如下所示，key是UCO，value是TaxiTotal，应该是TaxiIn和TaxiOut两列的总和，如何对两列求和？

我目前的解决方案TaxiIn + TaxiOut结果是一个粘贴数字，比如333+444 = 333444，我需要它是777，代码怎么写？

#! /usr/bin/env python

import sys

# -- Airline Data
# Year, Month, DayofMonth, DayOfWeek, DepTime, CRSDepTime, ArrTime, CRSArrTime, UniqueCarrier, FlightNum,
# TailNum, ActualElapsedTime, CRSElapsedTime, AirTime, ArrDelay, DepDelay, Origin, Dest,         Distance, TaxiIn,
# TaxiOut, Cancelled, CancellationCode, Diverted, CarrierDelay, WeatherDelay, NASDelay, SecurityDelay, LateAircraftDelay

for line in sys.stdin:
    line = line.strip()
    unpacked = line.split(",")
    Year, Month, DayofMonth, DayOfWeek, DepTime, CRSDepTime, ArrTime, CRSArrTime, UniqueCarrier, FlightNum, TailNum, ActualElapsedTime, CRSElapsedTime, AirTime, ArrDelay, DepDelay, Origin, Dest, Distance, TaxiIn,TaxiOut, Cancelled, CancellationCode, Diverted, CarrierDelay, WeatherDelay, NASDelay, SecurityDelay, LateAircraftDelay = line.split(",")
    UCO = "-".join([UniqueCarrier, Origin])
    results = [UCO, TaxiIn+TaxiOut]
    print("\t".join(results))

Answer 1

将TaxiIn + TaxiOut转换为：

int(TaxiIn) + int(TaxiOut)

请参阅以下示例：

In [1612]: TaxiIn = '333'                                                                                                                                                                                   

In [1613]: TaxiOut = '444'                                                                                                                                                                                  

In [1614]: TaxiIn + TaxiOut                                                                                                                                                                                 
Out[1614]: '333444'

In [1615]: int(TaxiIn) + int(TaxiOut)                                                                                                                                                                       
Out[1615]: 777

你不能有字符串的数字总和，因为将str转换为int或float 。

你的代码应该是：

results = [UCO, str(int(TaxiIn) + int(TaxiOut))]
print("\t".join(results))