看起来你需要一个笛卡尔积在袋子和它本身之间。要做到这一点，你需要使用扁平（袋）两次。
代码：

inpt = load '.../group.txt' using PigStorage(',') as (id, val);
grp = group inpt by (id);
id_grp = foreach grp generate group as id, inpt.val as value_bag;
result = foreach id_grp generate id, FLATTEN(value_bag) as v1, FLATTEN(value_bag) as v2; 
dump result;

请注意，大袋子会产生很多行。为了避免这种情况，可以在展平之前使用top（…）：

inpt = load '....group.txt' using PigStorage(',')  as (id, val);
grp = group inpt by (id);
id_grp = foreach grp generate group as id, inpt.val as values;
result = foreach id_grp {
    limited_bag = TOP(50, 0, values); -- all sorts of filtering could be done here
    generate id, FLATTEN(limited_bag) as v1, FLATTEN(limited_bag) as v2; 
};
dump result;

对于特定的输出，可以在展平之前使用一些过滤：

inpt = load '..../group.txt' as (id, val);
grp = group inpt by (id);
id_grp = foreach grp generate group as id, inpt.val as values;
result = foreach id_grp {
    l = filter values by val == 'b1' or val == 'b2';
    generate id, FLATTEN(l) as v1, FLATTEN(values) as v2; 
};
result = filter result by v1 != v2;

希望对你有帮助。
干杯

与此相关的还有datafu udf库中的unorderedpairs函数。它生成一个包中所有项目的对（在您的情况下是您的分组包）

你可以用 GROUP ALL 要生成的pig语句

A  = -- Some bag
B  = -- Another bag
groupedB = group B ALL;
result   = foreach A GENERATE 
    TOTUPLE(*), groupedB.$1;
-- Will generate
((a1), {(b1, b2, b3)})
((a2), {(b1, b2, b3)})
((a3), {(b1, b2, b3)})
...