The FILTER operator is used to select the required tuples from a relation based on a condition.

Syntax

Given below is the syntax of theFILTERoperator.

grunt
>
 Relation2_name = FILTER Relation1_name BY (condition);

Example

Assume that we have a file namedstudent_details.txtin the HDFS directory/pig_data/as shown below.

student_details.txt

001,Rajiv,Reddy,21,9848022337,Hyderabad
002,siddarth,Battacharya,22,9848022338,Kolkata
003,Rajesh,Khanna,22,9848022339,Delhi 
004,Preethi,Agarwal,21,9848022330,Pune 
005,Trupthi,Mohanthy,23,9848022336,Bhuwaneshwar 
006,Archana,Mishra,23,9848022335,Chennai 
007,Komal,Nayak,24,9848022334,trivendram 
008,Bharathi,Nambiayar,24,9848022333,Chennai

And we have loaded this file into Pig with the relation namestudent_detailsas shown below.

grunt
>
 student_details 
=
 LOAD 
'hdfs://localhost:9000/pig_data/student_details.txt'
 USING 
PigStorage
(
','
)
as
(
id
:
int
,
 firstname
:
chararray
,
 lastname
:
chararray
,
 age
:
int
,
 phone
:
chararray
,
 city
:
chararray
);

Let us now use the Filter operator to get the details of the students who belong to the city Chennai.

filter_data 
=
 FILTER student_details BY city 
==
'Chennai'
;

Verification

Verify the relation filter_data using the DUMP operator as shown below.

grunt
>
Dump
 filter_data
;

Output

It will produce the following output, displaying the contents of the relationfilter_dataas follows.

(6,Archana,Mishra,23,9848022335,Chennai)
(8,Bharathi,Nambiayar,24,9848022333,Chennai)