如何從豬列中獲得最大值？

Question

我有一個表，我想查詢列的總和值。下面是該表的詳細信息：

grunt>teams_raw = load '/usr/input/Teams.csv' using org.apache.pig.piggybank.storage.CSVExcelStorage(',', 'NO_MULTILINE', 'UNIX', 'SKIP_INPUT_HEADER'); 
grunt>teams = foreach teams_raw generate $0 as year:int, $1 as lgID, $2 as tmID, $8 as g:float, $9 as w:float, $11 as t:float, $18 as name; 
grunt> describe teams 
teams: {year: bytearray,lgID: bytearray,tmID: bytearray,g: bytearray,w: bytearray,t: bytearray,name: bytearray}; 
grunt> gry_by_team = group teams by tmID; 

試圖從teams表中獲取的g總和值時，我得到以下錯誤：

grunt> win = foreach grp_by_team generate group, SUM(teams.g) as win; 
grunt>DUMP win 
17/05/06 15:32:14 ERROR mapreduce.MRPigStatsUtil: 1 map reduce job(s) failed! 
17/05/06 15:32:14 ERROR grunt.Grunt: ERROR 1066: Unable to open iterator for alias win 
Details at logfile: /Users/joey/dev/bigdata/pig_1494048371690.log 

在日誌文件中，我看到了下面的例外。

================================================================================ 
Pig Stack Trace 
--------------- 
ERROR 1066: Unable to open iterator for alias win 

org.apache.pig.impl.logicalLayer.FrontendException: ERROR 1066: Unable to open iterator for alias win 
     at org.apache.pig.PigServer.openIterator(PigServer.java:1019) 
     at org.apache.pig.tools.grunt.GruntParser.processDump(GruntParser.java:747) 
     at org.apache.pig.tools.pigscript.parser.PigScriptParser.parse(PigScriptParser.java:376) 
     at org.apache.pig.tools.grunt.GruntParser.parseStopOnError(GruntParser.java:231) 
     at org.apache.pig.tools.grunt.GruntParser.parseStopOnError(GruntParser.java:206) 
     at org.apache.pig.tools.grunt.Grunt.run(Grunt.java:66) 
     at org.apache.pig.Main.run(Main.java:564) 
     at org.apache.pig.Main.main(Main.java:176) 
     at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) 
     at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) 
     at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) 
     at java.lang.reflect.Method.invoke(Method.java:498) 
     at org.apache.hadoop.util.RunJar.run(RunJar.java:234) 
     at org.apache.hadoop.util.RunJar.main(RunJar.java:148) 
Caused by: java.io.IOException: Job terminated with anomalous status FAILED 
     at org.apache.pig.PigServer.openIterator(PigServer.java:1011) 
     ... 13 more 
================================================================================ 

下面

是teams和gry_by_team轉儲數據：

grunt>dump teams 
... 
(1994,NHL,TBL,48,17,3,Tampa Bay Lightning) 
(1994,NHL,TOR,48,21,8,Toronto Maple Leafs) 
(1994,NHL,VAN,48,18,12,Vancouver Canucks) 
(1994,NHL,WAS,48,22,8,Washington Capitals) 
(1994,NHL,WIN,48,16,7,Winnipeg Jets) 
(1995,NHL,ANA,82,35,8,Mighty Ducks of Anaheim) 
(1995,NHL,BOS,82,40,11,Boston Bruins) 
(1995,NHL,BUF,82,33,7,Buffalo Sabres) 
(1995,NHL,CAL,82,34,11,Calgary Flames) 
... 

grunt>dump gry_by_team 
... 
(1912,NHA,TBS,20,9,0,Toronto Blueshirts),(1916,NHA,TBS,14,7,0,Toronto Blueshirts),(1914,NHA,TBS,20,8,0,Toronto Blueshirts)}) 
(TO1,{(1912,NHA,TO1,20,7,0,Toronto Tecumsehs)}) 
(TOA,{(1917,NHL,TOA,22,13,0,Toronto Arenas),(1918,NHL,TOA,18,5,0,Toronto Arenas)}) 
(TOB,{(1916,NHA,TOB,14,7,0,228th Battalion)}) 
(TOO,{(1913,NHA,TOO,20,4,0,Toronto Ontarios),(1914,NHA,TOO,20,7,0,Toronto Ontarios/Shamrocks)}) 
... 

我不知道有什麼錯我的代碼。

下面是我使用Hadoop和豬版本：

$ pig --version 
Apache Pig version 0.16.0 (r1746530) 
compiled Jun 01 2016, 23:10:49 

$ hadoop version 
Hadoop 2.8.0 
Subversion https://git-wip-us.apache.org/repos/asf/hadoop.git -r 91f2b7a13d1e97be65db92ddabc627cc29ac0009 
Compiled by jdu on 2017-03-17T04:12Z 
Compiled with protoc 2.5.0 
From source with checksum 60125541c2b3e266cbf3becc5bda666 
This command was run using /usr/local/Cellar/hadoop/2.8.0/libexec/share/hadoop/common/hadoop-common-2.8.0.jar 

Answer 1

win = foreach grp_by_team generate group, SUM(teams.g) as win; 

在您的代碼列g數據類型是bytearray。

SUM使用以下數據類型：int, long, float, double, bigdecimal, biginteger or bytearray cast as double.。在這裏您需要將bytearray作爲double。請參閱pig documentation瞭解更多信息。

未找到您在代碼grunt>teams = foreach teams_raw generate $0 as year:int, $1 as lgID, $2 as tmID, $8 as g:float, $9 as w:float, $11 as t:float, $18 as name;中定義的模式。因此，您最好指定模式以及加載語句。

例如：A = LOAD 'data' AS (a:chararray, b:int, c:int);