Pig Scripts calling in built function as well as user defined function

Code snippet showing how to call an in built as well as user defined function from pig latin

Pig Script Calling in-built function

A = LOAD '/home/Sample.txt' using PigStorage('\t') AS (f1:chararray,f2:chararray,f3:chararray);--Sample.txt is delimited with '\t'

B = FOREACH A GENERATE f1,f2,f3,UPPER(f3);--Calling the inbuilt function UPPER

DUMP B;--Displays the contents of B

Pig Script Calling UDF

Register /home/startsWith.jar ;--give the path of the jar file

A = LOAD '/home/Sample.txt' using PigStorage('\t') AS (f1:chararray,f2:chararray,f3:chararray);

B = FOREACH A GENERATE f1,f2,com.tcs.startsWith(f3,'c');--call the udf using fully qualified class name

DUMP B;--Displays the contents of B

import java.io.IOException; 

import org.apache.pig.FilterFunc; 
import org.apache.pig.PigWarning; 
import org.apache.pig.backend.executionengine.ExecException; 
import org.apache.pig.data.Tuple; 

/** 
 * This UDF is used to Test if string starts with the specified prefix. Note 
 * this function returns true if the character sequence represented by the 
 * argument is a prefix of the character sequence represented by the string. 
 * false otherwise. Note also that true will be returned if the 2nd 
 * argument(prefix) is an empty string or is equal to this String 
 * */ 
public class startsWith extends FilterFunc { 

 @Override 
 public Boolean exec(Tuple input) throws IOException { 

  if (input.size() != 2) { 
   String msg = "startsWith: Only 2 parameters are allowed."; 
   throw new IOException(msg); 
  } 
  if (input.get(0) == null) { 

   return null; 
  } 
  try { 

   if (!input.get(1).equals(null)) { 
    String str1 = (String) input.get(0); 
    String str2 = (String) input.get(1); 
    return str1.startsWith(str2); 
   } 

  } catch (ExecException e) { 
   warn("Error reading input: " + e.getMessage(), 
     PigWarning.UDF_WARNING_1); 

  } 
  return null; 

 } 
}