排序元組基於多的Fileds

Question

我想基於降序排列三場一包內的元組進行排序..

例：假設我有以下的包創建的分組：

{(s,3,my),(w,7,pr),(q,2,je)} 

我想排序在$ 0，$ 1，$ 2字段的上述分組袋中的元組，這樣首先它將排序所有元組中的$ 0。它將選擇最大$ 0值的元組。如果所有元組的$ 0都是相同的，那麼它將按$ 1排序，依此類推。

排序應通過迭代過程爲所有分組的行李。

假設，如果我們有databag類似：

{(21,25,34),(21,28,64),(21,25,52)} 

然後根據需要輸出應該是這樣的：

{(21,25,34),(21,25,52),(21,28,64)} 

請讓我知道如果你需要任何更多的澄清

Answer 1

訂購你的元組嵌套foreach。這將工作。

輸入：

(1,s,3,my) 
(1,w,7,pr) 
(1,q,2,je) 


A = LOAD 'file' using PigStorage(',') AS (a:chararray,b:chararray,c:chararray,d:chararray); 
B = GROUP A BY a;                        
C = FOREACH B GENERATE A;                      
D = FOREACH C {                        
od = ORDER A BY b, c, d;                      
GENERATE od;                         
}; 

DUMP C測試結果（這類似於你的數據）：

({(1,s,3,my),(1,w,7,pr),(1,q,2,je)}) 

輸出：

({(1,q,2,je),(1,s,3,my),(1,w,7,pr)}) 

這將爲所有的情況下工作。

生成具有最高值的元組：

A = LOAD 'file' using PigStorage(',') AS (a:chararray,b:chararray,c:chararray,d:chararray); 
B = GROUP A BY a;                        
C = FOREACH B GENERATE A;                      
D = FOREACH C { 
od = ORDER A BY b desc , c desc , d desc; 
od1 = LIMIT od 1;       
GENERATE od1;        
}; 
dump D; 

生成具有最高值的元組，如果所有的三個區域是不同的，如果所有的記錄都相同，或者如果場1和場2都相同，則全部歸還元組。

A = LOAD 'file' using PigStorage(',') AS (a:chararray,b:chararray,c:chararray,d:chararray); 
B = GROUP A BY a;                        
C = FOREACH B GENERATE A; 
F = RANK C; //rank used to separate out the value if two tuples are same          
R = FOREACH F {  
dis = distinct A;          
GENERATE rank_C,COUNT(dis) AS (cnt:long),A;     
}; 
R3 = FILTER R BY cnt!=1; // filter if all the tuples are same 
R4 = FOREACH R3 {       
fil1 = ORDER A by b desc, c desc, d desc; 
fil2 = LIMIT fil1 1;      
GENERATE rank_C,fil2;        
}; // find largest tuple except if all the tuples are same. 
R5 = FILTER R BY cnt==1; // only contains if all the tuples are same 
R6 = FOREACH R5 GENERATE A ; // generate required fields 
F1 = FOREACH F GENERATE rank_C,FLATTEN(A); 
F2 = GROUP F1 BY (rank_C, A::b, A::c); // group by field 1,field 2 
F3 = FOREACH F2 GENERATE COUNT(F1) AS (cnt1:long) ,F1; // if count = 2 then Tuples are same on field 1 and field 2 
F4 = FILTER F3 BY cnt1==2; //separate that alone 
F5 = FOREACH F4 {      
DIS = distinct F1;     
GENERATE flatten(DIS); 
}; 
F8 = JOIN F BY rank_C, F5 by rank_C; 
F9 = FOREACH F8 GENERATE F::A; 
Z = cross R4,F5; // cross done to genearte if all the tuples are different 
Z1 = FILTER Z BY R4::rank_C!=F5::DIS::rank_C; 
Z2 = FOREACH Z1 GENERATE FLATTEN(R4::fil2); 
res = UNION Z2,R6,F9; // Z2 - contains value if all the three fields in the tuple are diff holds highest value, 
//R6 - contains value if all the three fields in the tuple are same 
//F9 - conatains if two fields of the tuples are same 
dump res;