CooccurrenceMetricCalculator.java

/*
 * Copyright 2013, 2014 Deutsche Nationalbibliothek
 *
 * Licensed under the Apache License, Version 2.0 the "License";
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.culturegraph.mf.statistics;

import java.util.ArrayList;
import java.util.List;

import org.culturegraph.mf.framework.FluxCommand;
import org.culturegraph.mf.framework.annotations.Description;
import org.culturegraph.mf.framework.annotations.In;
import org.culturegraph.mf.framework.annotations.Out;
import org.culturegraph.mf.framework.objects.Triple;

/**
 * Calculates values for various co-occurrence metrics. The expected inputs are
 * triples containing as subject the var name and as object the count. Marginal
 * counts must appear first, joint counts second. Marginal counts must be
 * written as 1:A, Joint counts as 2:A&B
 *
 * @author Markus Geipel
 *
 */
@Description("Calculates values for various cooccurrence metrics. The expected inputs are triples containing as subject the var name and as object the count. "
		+ "Marginal counts must appear first, joint counts second. Marinal counts must be written as 1:A, Joint counts as 2:A&B")
@In(Triple.class)
@Out(Triple.class)
@FluxCommand("calculate-metrics")
public final class CooccurrenceMetricCalculator extends AbstractCountProcessor {

	/**
	 * implementation of the different metrics
	 */
	enum Metric {
		X2 {
			@Override
			double calculate(final int countA, final int countB, final int countAandB, final int total) {
				final double o12 = countA - countAandB;
				final double o21 = countB - countAandB;
				final double o22 = total - countAandB;
				final double d = (countAandB * o22) - (o12 * o21);

				final double x2 = total * Math.pow(d, 2)
						/ ((countAandB + o12) * (countAandB + o21) * (o12 + o22) * (o21 + o22));
				return x2 * Math.signum(d);
			}
		},
		F {
			@Override
			double calculate(final int countA, final int countB, final int countAandB, final int total) {
				final double pa = (double) countA / total;
				final double pb = (double) countB / total;
				final double pab = (double) countAandB / total;
				final double precission = pab / pa;
				final double recall = pab / pb;

				return 2 * precission * recall / (precission + recall);
			}
		},
		PRECISSION {
			@Override
			double calculate(final int countA, final int countB, final int countAandB, final int total) {
				final double pa = (double) countA / total;
				final double pab = (double) countAandB / total;
				return pab / pa;
			}
		},
		RECALL {
			@Override
			double calculate(final int countA, final int countB, final int countAandB, final int total) {
				final double pb = (double) countB / total;
				final double pab = (double) countAandB / total;
				return pab / pb;
			}
		},
		JACCARD {
			@Override
			double calculate(final int countA, final int countB, final int countAandB, final int total) {
				return countAandB / (double)(countA + countB - countAandB);
			}
		};

		abstract double calculate(final int countA, final int countB, final int countAandB, final int total);
	}

	private static final int MIN_COUNT = 5;

	private final List<Metric> metrics = new ArrayList<Metric>();

	public CooccurrenceMetricCalculator(final String allMetrics) {
		final String[] metrics = allMetrics.split("\\s*,\\s*");
		setMinCount(MIN_COUNT);
		for (String metric : metrics) {
			this.metrics.add(Metric.valueOf(metric));
		}
	}

	public CooccurrenceMetricCalculator(final Metric... metrics) {
		setMinCount(MIN_COUNT);
		for (Metric metric : metrics) {
			this.metrics.add(metric);
		}
	}

	@Override
	protected void processCount(final String varA, final String varB, final int countA, final int countB,
			final int countAandB) {
		for (Metric metric : metrics) {
			final double value = metric.calculate(countA, countB, countAandB, getTotal());
			getReceiver().process(new Triple(varA + "&" + varB, metric.toString(), String.valueOf(value)));
		}
	}
}