原始数据: $head -10 mv_0006890.txt 6890: 1735266,1,2004-04-02 1008399,1,2004-06-22 2360117,2,2003-11-08 1294425,2,2004-03-15 439931,4,2004-03-27 1583311,1,2004-03-11 2431832,3,2005-02-13 620771,2,2004-03-20 1110906,1,2004-03-04 结果数据:user_id movie_id rati