Question

我的结构X的关系X: {group: chararray,inboundCount: {(name: chararray,inb: long)},outboundCount: {(name: chararray,out: long)}}如下：

(IAD,{},{(IAD,25)})
(LAX,{},{(LAX,2)})
(ORD,{(ORD,27)},{})
(PDX,{},{(PDX,3)}) 
(SFO,{(SFO,3)},{})

我想要一个带有以下结构final: {airport: chararray,inbound: long,outbound: long}的输出，输出为：

(IAD,,25)
(LAX,,2)
(ORD,27,)
(PDX,,3)
(SFO,3,)

我尝试了以下代码，它提供了我想要的输出结构。但没有任何印刷品。是因为零值袋？。

final = foreach X generate group as airport,FLATTEN(inboundCount.inb) as inbound,FLATTEN(outboundCount.out) as outbound;

请帮帮我。

修改我通过执行以下命令得到了这个关系x。

A= load '/user/hduser/airline.csv' using PigStorage(',') as (year:int,month:int,dayofmonth:int,dayofweek:int,dep:int,CRS:int,Arr:int,CRSArr:int,UniqueCarrier:chararray,FlightNum:int,TailNum:chararray,ActualElapsedTime:int,CRSElapsed:int,AirTime:int,ArrDelay:int,DepDelay:int,Origin:chararray,Dest:chararray,Distance:int,TaxiIn:int,TaxiOut:int,Cancelled:int,CancelCode:chararray,Diverted:int,CarrierDelay:int,WeatherDelay:int,NASDelay:int,SecurityDelay:int,LateAircraft:int);
B= foreach A generate year,month,UniqueCarrier,FlightNum,TailNum,Origin,Dest;
inbound = group B by Dest;
inboundCount = foreach inbound generate group,COUNT(B.FlightNum) as inb;
outbound = group B by Origin;
outboundCount = foreach outbound generate group,COUNT(B.FlightNum) as out;
X = COGROUP inboundCount BY name, outboundCount BY name;

示例输入记录：

2008,1,31,4,1757,1155,2400,1758，UA，114，N845UA，243,243,217,362,362，LAX，ORD，1745,11,15,0，0,0,0,362,0,0 < / p>

Answer 1

你几乎就在那里。请尝试这个。只是应用SUM而不是展平

 A= load '/user/hduser/airline.csv' using PigStorage(',') as (year:int,month:int,dayofmonth:int,dayofweek:int,dep:int,CRS:int,Arr:int,CRSArr:int,UniqueCarrier:chararray,FlightNum:int,TailNum:chararray,ActualElapsedTime:int,CRSElapsed:int,AirTime:int,ArrDelay:int,DepDelay:int,Origin:chararray,Dest:chararray,Distance:int,TaxiIn:int,TaxiOut:int,Cancelled:int,CancelCode:chararray,Diverted:int,CarrierDelay:int,WeatherDelay:int,NASDelay:int,SecurityDelay:int,LateAircraft:int);

B= foreach A generate year,month,UniqueCarrier,FlightNum,TailNum,Origin,Dest;

inbound = group B by Dest;

inboundCount = foreach inbound generate group,COUNT(B.FlightNum) as inb;

outbound = group B by Origin;

outboundCount = foreach outbound generate group,COUNT(B.FlightNum) as out;

X = COGROUP inboundCount BY name, outboundCount BY name;

final_data = FOREACH X GENERATE group as airport, SUM(inboundCount.inb) as inb, SUM(outboundCount.out) as out;

dump final_data;

final_data的转储将为您提供预期的结果。

(IAD,,25)
(LAX,,2)
(ORD,27,)
(PDX,,3)
(SFO,3,)

如果需要，您仍然可以将NULL计数替换为0

 final_null_check = FOREACH final_data GENERATE airport,(inb is null ? 0 :inb) as inb_cnt, (out is null ? 0 : out) as out_cnt;

NULL后检查是否转储了final_null_check关系，您将得到如下所示的输出

 (IAD,0,25)
 (LAX,0,2)
 (ORD,27,0)
 (PDX,0,3)
 (SFO,3,0)

PIG：FLATTEN错误

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