LevenshteinDistance.java

package com.twitter.appprofiler.pig.piggybank;

import org.apache.commons.lang.StringUtils;
import org.apache.pig.EvalFunc;
import org.apache.pig.PigWarning;
import org.apache.pig.backend.executionengine.ExecException;
import org.apache.pig.data.DataByteArray;
import org.apache.pig.data.Tuple;

import java.io.IOException;

public class LevenshteinDistance extends EvalFunc<Integer> {
	protected static String getString(Tuple input, int index) throws ExecException {
		Object o = input.get(index);
		if (o instanceof String)
			return (String)o;
		else if (o instanceof DataByteArray)
			return new String(((DataByteArray)o).get());
		else
			throw new ClassCastException();
	}

	public Integer exec(Tuple input) throws IOException {
		if ((input == null) || (input.size() < 2) || (input.get(0) == null) || (input.get(1) == null))
			return null;

		try {
			String string1 = null;
			try {
				string1 = getString(input, 0);
			} catch (ClassCastException ex) {
				warn("can't cast first parameter to a string", PigWarning.UDF_WARNING_1);
			}

			String string2 = null;
			try {
				string2 = getString(input, 1);
			} catch (ClassCastException ex) {
				warn("can't cast second parameter to a string", PigWarning.UDF_WARNING_1);
			}
		
			return StringUtils.getLevenshteinDistance(string1, string2);
		} catch (Exception e) {
			warn("error", PigWarning.UDF_WARNING_2);
			return null;
		}
	}
}