阿帕奇豬AVG功能

Question

我想要做一個簡單的豬查詢，我需要找到電影的平均評級爲ID 178我已經嘗試了一些版本的下面和過濾器工作，但沒有AVG功能。任何人都可以建議嗎？由於

a = load '/user/pig/u.data' AS (userid:int, movieid:int, rating:double, timestamp:chararray); 
b = FOREACH a GENERATE AVG(rating) as rate, movieid; 
c = group b by rate; 
d= filter a by movieid==178; 
dump d; 

Answer 1

你應該movieid組

b = FILTER a BY (movieid == 178); 
c = GROUP b BY movied; 
d = FOREACH c GENERATE group AS movieid,AVG(a.rating) as rate;