试试这个：

A1 = LOAD 'Sandeep Rohan Mohan' USING PigStorage() AS (line:chararray);
B1 = LOAD 'MOHAN' USING PigStorage() AS (line:chararray);

A = FOREACH A1 GENERATE UPPER(line) AS line;
B = FOREACH B1 GENERATE UPPER(line) AS line;

C = COGROUP A BY line, B BY line;

D = FILTER C BY IsEmpty(B);

E = FOREACH D GENERATE group AS name;

DUMP E;

（罗汉）（桑德普）
另请参阅apache pig中的set操作

它是通过左外连接实现的，只考虑那些在$1中有空值的元组