PIG UDF to convert tuple to multiple tuple output - apache-pig

Question

I am new to PIG and I am trying to create a UDF which get a tuple and return multiple tuple based on a delimited. So I have written one UDF to read the below data file
2012/01/01 Name1 Category1|Category2|Category3
2012/01/01 Name2 Category2|Category3
2012/01/01 Name3 Category1|Category5
Basically i am trying to read $2 field
Category1|Category2|Category3
Category2|Category3
Category1|Category5
to get the output as :-
Category1, Category2, Category3
Category2, Category3
Category1, Category5
Below is the UDF code i have written..
package com.test.multipleTuple;
import java.io.IOException;
import org.apache.pig.EvalFunc;
import org.apache.pig.data.Tuple;
import org.apache.pig.data.TupleFactory;
public class TupleToMultipleTuple extends EvalFunc<String> {
#Override
public String exec(Tuple input) throws IOException {
// Keep the count of every cell in the
Tuple aux = TupleFactory.getInstance().newTuple();
if (input == null || input.size() == 0)
return null;
try {
String del = "\\|";
String str = (String) input.get(0);
String field[] = str.split(del);
for (String nxt : field) {
aux.append(nxt.trim().toString());
}
} catch (Exception e) {
throw new IOException("Caught exception processing input row ", e);
}
return aux.toDelimitedString(",");
}
}
created Jar --> TupleToMultipleTuple.jar
But I am getting the below error while executing it .
Pig Stack Trace
---------------
ERROR 1066: Unable to open iterator for alias B
org.apache.pig.impl.logicalLayer.FrontendException: ERROR 1066: Unable to open iterator for alias B
at org.apache.pig.PigServer.openIterator(PigServer.java:892)
at org.apache.pig.tools.grunt.GruntParser.processDump(GruntParser.java:774)
at org.apache.pig.tools.pigscript.parser.PigScriptParser.parse(PigScriptParser.java:372)
at org.apache.pig.tools.grunt.GruntParser.parseStopOnError(GruntParser.java:198)
at org.apache.pig.tools.grunt.GruntParser.parseStopOnError(GruntParser.java:173)
at org.apache.pig.tools.grunt.Grunt.run(Grunt.java:69)
at org.apache.pig.Main.run(Main.java:547)
at org.apache.pig.Main.main(Main.java:158)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:606)
at org.apache.hadoop.util.RunJar.run(RunJar.java:221)
at org.apache.hadoop.util.RunJar.main(RunJar.java:136)
Caused by: java.io.IOException: Job terminated with anomalous status FAILED
at org.apache.pig.PigServer.openIterator(PigServer.java:884)
... 13 more
Can you please help me in rectifying the issue. Thanks.
Pig script for applying the UDF..
REGISTER TupleToMultipleTuple.jar;
DEFINE myFunc com.test.multipleTuple.TupleToMultipleTuple();
A = load 'data.txt' USING PigStorage(' ');
B = foreach A generate myFunc($2);
dump B;

Answer 1

You can use the built-in split function like this:
flatten(STRSPLIT($2,'[|]',3))as(cat1:chararray,cat2:chararray,cat3:chararray)
and you will get 3 tuples named cat1, cat2 and cat2 typed as chararray and delimited by the current delimiter of the relation which they belong to.

Answer 2

Found the issue .. Issue was while parsing DayaByteArray to String.. used toString() to fix it
package com.test.multipleTuple;
import java.io.IOException;
import org.apache.pig.EvalFunc;
import org.apache.pig.data.Tuple;
import org.apache.pig.data.TupleFactory;
public class TupleToMultipleTuple extends EvalFunc<String> {
#Override
public String exec(Tuple input) throws IOException {
// Keep the count of every cell in the
Tuple aux = TupleFactory.getInstance().newTuple();
if (input == null || input.size() == 0)
return null;
try {
String del = "\\|";
String str = (String) input.get(0).toString();
String field[] = str.split(del);
for (String nxt : field) {
aux.append(nxt.trim().toString());
}
} catch (Exception e) {
throw new IOException("Caught exception processing input row ", e);
}
return aux.toDelimitedString(",");
}
}