用pig实现的矩阵乘

a = load '/user/hadoop/three_tuple_1.txt' as (line:int,col:int,value:int);

b = load '/user/hadoop/three_tuple_2.txt' as (line:int,col:int,value:int);
c = group a by line;
d = group b by col;
e = cross c,d;
f = foreach e generate c::group,d::group,flatten(c::a),flatten(d::b);
g = filter f by $3 == $5;
h = foreach g generate c::group,d::group,(c::a::value*d::b::value);
i = group h by (c::group,d::group);
j = foreach i generate flatten(group),SUM(h.$2);
dump j;