a.pig

-- data.txt
-- 10	1,2,3
-- 20	1,2

A = LOAD 'data.txt' USING PigStorage('\t') AS (key:int, values:chararray);
-- B = FOREACH A GENERATE key, FLATTEN(TOKENIZE(values, ',')) AS (value:int);
B = FOREACH A GENERATE key, FLATTEN(TOKENIZE(values, ',')) AS value;
C = FOREACH B GENERATE key, (int)value;
D = FILTER C BY value > 1;
DUMP D;