pig中使用的一些实例语法

在pig中， dump和store会分别完毕两个MR， 不会一起进行

1：载入名用正則表達式：

LOAD '/user/wizad/data/wizad/raw/2014-0{6,7-0,7-1,7-2,7-3,8}*/3_1/adwords*'

2：filter的几种简单使用方法：

按值过滤

FILTER clickDate_all BY log_type=='2';
FILTER mapping_table BY mapping_ad_network_id=='3' AND mapping_type=='5';
test =FILTER allRow BY (ad_id=='14997' OR ad_id=='14998' OR ad_id=='14999') AND log_type==2;
test=FILTER allRow BY (INDEXOF(ad_id,'14997')==0 OR INDEXOF(ad_id,'14998')==0 OR INDEXOF(ad_id,'14999')==0) AND log_type==2;

配合size函数

FILTER count_imei BY (SIZE(cimei)>14 AND SIZE(cimei)<17);

正則表達式

FILTER cimei2 BY NOT cimei MATCHES '^[0-9]*$';
FILTER cmac2 BY cmac MATCHES '/[A-Fd]{2}:[A-Fd]{2}:[A-Fd]{2}:[A-Fd]{2}:[A-Fd]{2}:[A-Fd]{2}/';

3：排序

ORDER province_count BY $2 DESC;


4：CONCAT函数的使用。可用于生成独立的一列，如count了的一个数，前面加一列名称
FOREACH origin_cleaned_data GENERATE CONCAT('<-_','->') AS cou,guid,log_type;
read_social_14 =FOREACH metadata_social_14 GENERATE CONCAT('14','=='),guid_social;
all_id =FOREACH allRow GENERATE id,CONCAT('_','-') as cc;

5：过滤空值，将空值改成取值unknown。

     条件表达式“（推断式）？a：b”的应用：直接对列操作

origin_historical = FOREACH origin_cleaned_data GENERATE wizad_ad_id,guid,log_type,
((province_region_id == '') ? 'unknown' : province_region_id)

6:切分成不同子集，按值：
 SPLIT geelyTuiGuang INTO android IF os_id==1,ios IF os_id==2;
 SPLIT ios INTO ios6 IF (INDEXOF(os_version,'7')!=0),ios7 IF INDEXOF(os_version,'7')==0;

SPLIT allCleaned INTO log_42 IF (
((chararray)$34=='1' OR (chararray)$34=='2' OR (chararray)$34=='3' OR (chararray)$34=='1' OR (chararray)$34=='4')
AND
(INDEXOF((chararray)$35,'.')>0)
AND
((chararray)$36=='1' OR (chararray)$36=='')

),
log_43 IF (
((chararray)$34=='1' OR (chararray)$34=='2')
AND
((chararray)$35=='1' OR (chararray)$35=='2' OR (chararray)$35=='3' OR (chararray)$35=='1' OR (chararray)$35=='4')
AND
(INDEXOF((chararray)$36,'.')>0)
);

7：replace函数替换值
 FOREACH ios6 GENERATE imei,mac_address as cmac,REPLACE(idfa,'null','');

8：数据流过滤

 en_guid =STREAM duimei THROUGH `awk -F"," '{if($3 == "null") print $1","$2","; else print $0}'`;

9：强制转换：

cleaned_data_42 =FOREACH log_42 GENERATE 
(chararray)$1  AS wizad_ad_id:chararray,
(chararray)$2  AS guid:chararray,
(chararray)$6  AS log_type:chararray,
(chararray)$18 AS imei:chararray,
(chararray)$22 AS idfa:chararray,
(chararray)$23 AS mac_address:chararray

10内置函数REGEX_EXTRACT，使用正則表達式：

allAdId =FOREACH allRow GENERATE REGEX_EXTRACT((chararray)$3,'(.*) (.*)',1) AS time,REGEX_EXTRACT((chararray)$0,'(.*)_(.*)',1) AS adn,$6 AS ad_id;

 allAdId =FOREACH allRow GENERATE REGEX_EXTRACT(create_time,'(.*) (.*)',1) AS time,ad_id;