如何从apache下的一个包里找到所有可能的排列组合 [英] How To Find All Possible Permutations From A Bag under apache pig
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问题描述
A = LOAD'data'AS f1:chararray;
DUMP A; ('B')
('C')
B = FOREACH A GENERATE $ 0 AS v1;
C = FOREACH A GENERATE $ 0 AS v2;
D = CROSS B,C;
我得到的结果如下:
DUMP D;
('A','A')
('A','B')
('A','C')
('B','A ')
('B','B')
('B','C')
('C','A')
('C','B' 'B')
('C','C')
m试图获得结果如下:
DUMP R;
('A','A')
('A','B')
('A','C')
('B','B ')
('B','C')
('C','C')
我该怎么做?我避免使用字符比较,因为可能在多行中出现多次出现的字符串
您可以过滤D删除你不想要的行。例如 A = load'testdata.txt';
B = foreach生成$ 0;
C =交叉A,B;
D =过滤器C减$ 0< = $ 1;
dump D;
打印出来
(C,C)
(B,C)
(B,B)
(A,C)
(A,B)
'(A,A)
当'testdata.txt'有
A
B
C
i'm trying to find all combinations possible using apache pig, i was able to generate permutation but i want to eliminate the replication of values i write this code :
A = LOAD 'data' AS f1:chararray;
DUMP A;
('A')
('B')
('C')
B = FOREACH A GENERATE $0 AS v1;
C = FOREACH A GENERATE $0 AS v2;
D = CROSS B, C;
And the result i obtained is like :
DUMP D;
('A', 'A')
('A', 'B')
('A', 'C')
('B', 'A')
('B', 'B')
('B', 'C')
('C', 'A')
('C', 'B')
('C', 'C')
but what i'm trying to obtain the result is like bellow
DUMP R;
('A', 'A')
('A', 'B')
('A', 'C')
('B', 'B')
('B', 'C')
('C', 'C')
how can i do this? i avoid to use comparison of characters because it's possible to have multiple occurrences of a string in more than a line
解决方案
You can FILTER D to remove the rows you don't want. For example
A = load 'testdata.txt';
B = foreach A generate $0;
C = Cross A, B;
D = filter C by $0 <= $1;
dump D;
which prints out
(C,C)
(B,C)
(B,B)
(A,C)
(A,B)
(A,A)
when 'testdata.txt' has
A
B
C
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