Apache Pig 区分和计数

Question

我正在尝试弄清楚以下问题。

有多少女性用户提供了至少 4 分的评分。我认为我的加入和过滤器是正确的，但我无法弄清楚不同的计数部分已尝试以下多个版本。

a = load '/user/pig/movie' AS (userid:int, movieid:int, rating:int, timestamp:chararray);
b = load '/user/pig/reviewer' using PigStorage('|') AS (userid:int, age:int, gender:chararray, occupation:chararray, zip:chararray);
a1 = filter a by rating == 4;
b1 = filter b by gender == 'F';
c = join a1 by userid, b1 by userid;
d = FOREACH c GENERATE COUNT(DISTINCT(userid));
dump d;

Answer 1

您必须在 COUNT 之前进行 GROUP。Ref:COUNT 需要前面的 GROUP ALL 语句用于全局计数和 GROUP BY 语句用于组计数。

d = GROUP c BY userid;
e = FOREACH d GENERATE COUNT(DISTINCT(b1.userid));
dump e;