Pig Cross 运算符 | Pig 教程

#Pig Cross 运算符
##Cross 运算符
CROSS操作符计算两个或两个以上关系的向量叉积。本章举例说明如何在Pig Latin中使用Cross运算符。
语法
下面给出的是CROSS运算符的语法。
```bash
grunt> Relation3_name = CROSS Relation1_name, Relation2_name;
```
假设我们在HDFS的/pig_data/目录中有两个文件，即customers.txt和orders.txt，如下所示。
```
1,Ramesh,32,Ahmedabad,2020.00
2,Khilan,25,Delhi,1500.00
3,kaushik,23,Kota,2020.00
4,Chaitali,25,Mumbai,6500.00
5,Hardik,27,Bhopal,8500.00
6,Komal,22,MP,4500.00
7,Muffy,24,Indore,10000.00
```
```
102,2019-10-08 00:00:00,3,3000
100,2019-10-08 00:00:00,3,1500
101,2019-11-20 00:00:00,2,1560
103,2018-05-20 00:00:00,4,2060
```
我们已将这两个文件与客户和订单的关系加载到Pig中，如下所示。
```bash
grunt> customers = LOAD 'hdfs://localhost:9000/pig_data/customers.txt' USING PigStorage(',')
   as (id:int, name:chararray, age:int, address:chararray, salary:int);

grunt> orders = LOAD 'hdfs://localhost:9000/pig_data/orders.txt' USING PigStorage(',')
   as (oid:int, date:chararray, customer_id:int, amount:int);
```
现在让我们使用这两个关系上的cross 运算符获得这两个关系的向量叉积，如下所示。
```bash
grunt> cross_data = CROSS customers, orders;
```
**验证**
使用DUMP运算符验证关系cross_data，如下所示。
```bash
grunt> Dump cross_data;
```
**输出**
它将产生以下输出，显示关系cross_data的内容。
```
(7,Muffy,24,Indore,10000,103,2018-05-20 00:00:00,4,2060)
(7,Muffy,24,Indore,10000,101,2019-11-20 00:00:00,2,1560)
(7,Muffy,24,Indore,10000,100,2019-10-08 00:00:00,3,1500)
(7,Muffy,24,Indore,10000,102,2019-10-08 00:00:00,3,3000)
(6,Komal,22,MP,4500,103,2018-05-20 00:00:00,4,2060)
(6,Komal,22,MP,4500,101,2019-11-20 00:00:00,2,1560)
(6,Komal,22,MP,4500,100,2019-10-08 00:00:00,3,1500)
(6,Komal,22,MP,4500,102,2019-10-08 00:00:00,3,3000)
(5,Hardik,27,Bhopal,8500,103,2018-05-20 00:00:00,4,2060)
(5,Hardik,27,Bhopal,8500,101,2019-11-20 00:00:00,2,1560)
(5,Hardik,27,Bhopal,8500,100,2019-10-08 00:00:00,3,1500)
(5,Hardik,27,Bhopal,8500,102,2019-10-08 00:00:00,3,3000)
(4,Chaitali,25,Mumbai,6500,103,2018-05-20 00:00:00,4,2060)
(4,Chaitali,25,Mumbai,6500,101,2019-20 00:00:00,4,2060)
(2,Khilan,25,Delhi,1500,101,2019-11-20 00:00:00,2,1560)
(2,Khilan,25,Delhi,1500,100,2019-10-08 00:00:00,3,1500)
(2,Khilan,25,Delhi,1500,102,2019-10-08 00:00:00,3,3000)
(1,Ramesh,32,Ahmedabad,2020,103,2018-05-20 00:00:00,4,2060)
(1,Ramesh,32,Ahmedabad,2020,101,2019-11-20 00:00:00,2,1560)
(1,Ramesh,32,Ahmedabad,2020,100,2019-10-08 00:00:00,3,1500)
(1,Ramesh,32,Ahmedabad,2020,102,2019-10-08 00:00:00,3,3000)-11-20 00:00:00,2,1560)
(4,Chaitali,25,Mumbai,6500,100,2019-10-08 00:00:00,3,1500)
(4,Chaitali,25,Mumbai,6500,102,2019-10-08 00:00:00,3,3000) 
(3,kaushik,23,Kota,2020,103,2018-05-20 00:00:00,4,2060) 
(3,kaushik,23,Kota,2020,101,2019-11-20 00:00:00,2,1560) 
(3,kaushik,23,Kota,2020,100,2019-10-08 00:00:00,3,1500) 
(3,kaushik,23,Kota,2020,102,2019-10-08 00:00:00,3,3000) 
(2,Khilan,25,Delhi,1500,103,2018-05-20 00:00:00,4,2060) 
(2,Khilan,25,Delhi,1500,101,2019-11-20 00:00:00,2,1560) 
(2,Khilan,25,Delhi,1500,100,2019-10-08 00:00:00,3,1500)
(2,Khilan,25,Delhi,1500,102,2019-10-08 00:00:00,3,3000) 
(1,Ramesh,32,Ahmedabad,2020,103,2018-05-20 00:00:00,4,2060) 
(1,Ramesh,32,Ahmedabad,2020,101,2019-11-20 00:00:00,2,1560) 
(1,Ramesh,32,Ahmedabad,2020,100,2019-10-08 00:00:00,3,1500) 
(1,Ramesh,32,Ahmedabad,2020,102,2019-10-08 00:00:00,3,3000) 
```

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