像袋子一样压扁元组 [英] Flatten tuple like a bag

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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