Max在一個袋子

Question

跟進問題Pig equivalent of SQL GREATEST/LEAST?

我做

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;

所描述的，這讓我的最大值

（真棒順便說一句！）。你怎麼知道這個數值原來在（a，b或c）中？

Answer 1

簡單的方法可以是：

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';