This function is used to replace all the characters in a given string with the new characters.
Given below is the syntax of the REPLACE() function. This function accepts three parameters, namely,
string − The string that is to be replaced. If we want to replace the string within a relation, we have to pass the column name the string belongs to.
regEXP − Here we have to pass the string/regular expression we want to replace.
newChar − Here we have to pass the new value of the string.
grunt> REPLACE(string, 'regExp', 'newChar');
Assume that there is a file named emp.txt in the HDFS directory /pig_data/ as shown below. This file contains the employee details such as id, name, age, and city.
001,Robin,22,newyork 002,BOB,23,Kolkata 003,Maya,23,Tokyo 004,Sara,25,London 005,David,23,Bhuwaneshwar 006,Maggy,22,Chennai 007,Robert,22,newyork 008,Syam,23,Kolkata 009,Mary,25,Tokyo 010,Saran,25,London 011,Stacy,25,Bhuwaneshwar 012,Kelly,22,Chennai
And, we have loaded this file into Pig with a relation named emp_data as shown below.
grunt> emp_data = LOAD 'hdfs://localhost:9000/pig_data/emp1.txt' USING PigStorage(',') as (id:int, name:chararray, age:int, city:chararray);
Following is an example of the REPLACE() function. In this example, we have replaced the name of the city Bhuwaneshwar with a shorter form Bhuw.
grunt> replace_data = FOREACH emp_data GENERATE (id,city),REPLACE(city,'Bhuwaneshwar','Bhuw');
The above statement replaces the string 'Bhuwaneshwar' with 'Bhuw' in the column named city in the emp_data relation and returns the result. This result is stored in the relation named replace_data. Verify the content of the relation replace_data using the Dump operator as shown below.
grunt> Dump replace_data; ((1,newyork),newyork) ((2,Kolkata),Kolkata) ((3,Tokyo),Tokyo) ((4,London),London) ((5,Bhuwaneshwar),Bhuw) ((6,Chennai),Chennai) ((7,newyork),newyork) ((8,Kolkata),Kolkata) ((9,Tokyo),Tokyo) ((10,London),London) ((11,Bhuwaneshwar),Bhuw) ((12,Chennai),Chennai)