Pig UDF (User Defined Functions)

For custom processing Pig provides user defined functions (UDFs) . Currently PIG UDFs are implemented in three languages Java, Python and Ruby.

All UDFs must extend "org.apache.pig.EvalFunc"
All functions must override "exec" method.

Let's see an example of simple EVAL Function to convert to upper.

packagemyudfs;
importjava.io.IOException;
importorg.apache.pig.EvalFunc;
importorg.apache.pig.data.Tuple;
public class UPPER extends EvalFunc<String>
 {
public String exec(Tuple input) throws IOException {
if (input == null || input.size() == 0)
return null;
try{
            String str = (String)input.get(0);
returnstr.toUpperCase();
}catch(Exception e){
throw new IOException("Caught exception processing input row ", e);
        }
    }
  }

Create a jar of the above code as myudfs.jar.

Now write the script in a file and save it as .pig. Here I am using script.pig.

-- script.pig
REGISTER myudfs.jar;
A = LOAD 'data' AS (name: chararray, age: int, gpa: float);
B = FOREACH A GENERATE myudfs.UPPER(name);
DUMP B;

Finally run the script in the terminal to get the output.

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Pig UDF (User Defined Functions)