python - 将两列相加，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，键是UCO，值是TaxiTotal，应该是TaxiIn和TaxiOut两列的和，如何对这两列求和？

我目前的解决方案TaxiIn + TaxiOut 结果是一个粘贴号，比如333+444 = 333444，我需要是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

转换TaxiIn + TaxiOut为：

int(TaxiIn) + int(TaxiOut)

请参见下面的示例：

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，因为它转换str为intor float。

你的代码应该是：

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