猪编程以通过计数(*)对组进行拆分 [英] pig programming to use split on group by having count(*)
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问题描述
输入文件为:
2, cornflakes, Regular,General Mills, 12
3, cornflakes, Mixed Nuts, Post, 14
4, chocolate syrup, Regular, Hersheys, 5
5, chocolate syrup, No High Fructose, Hersheys, 8
6, chocolate syrup, Regular, Ghirardeli, 6
7, chocolate syrup, Strawberry Flavor, Ghirardeli, 7
filter3 = LOAD 'location_of_file' using PigStorage('\t') as (item_sl : int, item : chararray, type: chararray, manufacturer: chararray, price : int);
SPLIT filter3 INTO filter4 IF (FOREACH (filter3 GROUP BY item) GENERATE group, COUNT(item < 3)), filter6_pass OTHERWISE;
这就像在具有 count(*) < 的项目上使用带有 group by 的 SQL3
It is like having a SQL with a group by on item having count(*) < 3
所需的输出是:
4, chocolate syrup, Regular, Hersheys, 5
5, chocolate syrup, No High Fructose, Hersheys, 8
6, chocolate syrup, Regular, Ghirardeli, 6
7, chocolate syrup, Strawberry Flavor, Ghirardeli, 7
推荐答案
按项目分组,获取计数,然后对计数使用过滤器
Group by item, get the count and then use filter on the count
A = LOAD 'location_of_file' using PigStorage('\t') as (item_sl : int, item : chararray, type: chararray, manufacturer: chararray, price : int);
B = GROUP A BY item;
C = FOREACH B GENERATE group,COUNT(A.item) AS Total;
D = FILTER C BY Total > 3;
E = JOIN A BY item,D BY $0;
F = FOREACH E GENERATE $0..$4;
DUMP F;
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