pig基本语法——filter distinct foreach

1、主要参考：

https://book.itxueyuan.com/3b7D/9PxP

filter主要用户过滤数据，根据条件查询

基础数据:

==============================================

[root@cdh1 data]# cat demodata

xiaoxiao,12,12.1f

aaa,13,1.1f

kjkj,12,12.1f

ddf,19,12.8f

youyou,89,12.3f

==============================================

grunt> A = load '/root/xytest/pig/data/demodata' using PigStorage(',') as (name:chararray,age:int,gpa:float);

grunt> B = filter A by age > 16;

grunt> dump B;

输出结果：

(ddf,19,12.8)

(youyou,89,12.3)

==============================================

主要参考：

https://book.itxueyuan.com/3b7D/gJEW

distinct主要用于排重

==============================================

数据如下：

aa

bb

aa

bb

cc

==============================================

grunt> A = load '/root/xytest/pig/data/demodata3' using PigStorage();

grunt> B = distinct A;

grunt> dump B;

输出结果如下：

(aa)

(bb)

(cc)

==============================================

主要参考：

https://book.itxueyuan.com/3b7D/bDZv

foreach主要用户获取指定的数据集

==============================================

[root@cdh1 data]# cat demodata

xiaoxiao,12,12.1f

aaa,13,1.1f

kjkj,12,12.1f

ddf,19,12.8f

youyou,89,12.3f

==============================================

grunt> A = load '/root/xytest/pig/data/demodata' using PigStorage(',') as (name:chararray,age:int,gpa:float);

grunt> B = foreach A generate name,gpa;

grunt> dump B;

运行结果：

(xiaoxiao,12.1)

(aaa,1.1)

(kjkj,12.1)

(ddf,12.8)

(youyou,12.3)

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