像袋子一样压扁元组 [英] Flatten tuple like a bag
本文介绍了像袋子一样压扁元组的处理方法,对大家解决问题具有一定的参考价值,需要的朋友们下面随着小编来一起学习吧!
问题描述
我的数据集如下所示:
( A, (1,2) )
( B, (2,9) )
我想展平"Pig 中的元组,基本上为内部元组中找到的每个值重复每条记录,这样预期的输出是:
I would like to "flatten" the tuples in Pig, basically repeating each record for each value found in the inner-tuple, such that the expected output is:
( A, 1 )
( A, 2 )
( B, 2 )
( B, 9 )
我知道当元组 (1,2) 和 (2,9) 是袋子时,这是可能的.
I know this is possible when the tuples (1,2) and (2,9) are bags instead.
推荐答案
你的洞察力很好;可以通过在包中转换元组来实现.我们要针对的模式是:{a: chararray,{(chararray)}} 例如:(A,{(1),(2)})
Your insight is good; it's possible by transforming the tuple in a bag. The schema we want to aim for is: {a: chararray,{(chararray)}} for example: (A,{(1),(2)})
这是您问题的解决方案:
Here is the solution to your problem:
A = LOAD 'data.txt' AS (a:chararray,b:(b1:chararray,b2:chararray));
B = FOREACH A GENERATE a, TOBAG(b.b1,b.b2);
C = FOREACH B GENERATE a, FLATTEN($1);
神奇的部分是 TOBAG 运算符.
The magic part is the TOBAG operator.
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