如何統計具有PIG的唯一用戶的數量

Question

以下代碼片段不會完全返回我正在嘗試計算的內容;唯一用戶的數量。任何想法？

data = LOAD 'input_initial' AS (user_id,item_id,rating,timestamp); 
data = FOREACH data GENERATE user_id,item_id; 
STORE data INTO 'input_final'; 
data_users = FOREACH data GENERATE user_id; 
group_users = GROUP data_users BY user_id; 
count_users = FOREACH group_users GENERATE COUNT(data_users); 
STORE count_users INTO 'count_users'; 

Answer 1

你需要修改對「所有」，而不是單個字段的最後一組操作行爲：

group_users = GROUP data_users BY user_id; 
grp_all = GROUP group_users ALL; 
count_users = FOREACH grp_all GENERATE COUNT(group_users);