包中的最大值

Question

跟进问题Pig equivalent of SQL GREATEST / LEAST?

我做了

x = LOAD 'file:///a/b/c.csv' USING PigStorage() AS (a: int, b: int, c: int); y = FOREACH x GENERATE a AS a: int, b AS b: int, c AS c: int, MAX(TOBAG(a, b, c)) AS g: int;

如上所述，它获得了最大值（真棒btw！）。你怎么知道这个值最初在哪个列（a，b或c）？

Answer 1

简单的方法可以是：

z = FOREACH y GENERATE
      a,
      b,
      c,
      g,
      CASE WHEN
         g==a THEN 'a'
         g==b THEN 'b'
         g==c THEN 'c'
      END as 'which_column';