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Apache Ignite® is a Distributed Database For High-Performance Computing With In-Memory Speed.

There is a newer version: 2.15.0

/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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.apache.ignite.ml.math.distances;

import java.io.IOException;
import java.io.ObjectInput;
import java.io.ObjectOutput;
import org.apache.ignite.ml.math.Vector;
import org.apache.ignite.ml.math.exceptions.CardinalityException;
import org.apache.ignite.ml.math.util.MatrixUtil;

/**
 * Calculates the L₁ (sum of abs) distance between two points.
 */
public class ManhattanDistance implements DistanceMeasure {
    /** Serializable version identifier. */
    private static final long serialVersionUID = 8989556319784040040L;

    /** {@inheritDoc} */
    @Override public double compute(Vector a, Vector b)
        throws CardinalityException {
        return MatrixUtil.localCopyOf(a).minus(b).kNorm(1.0);
    }

    /** {@inheritDoc} */
    @Override public double compute(Vector a, double[] b) throws CardinalityException {
        throw new UnsupportedOperationException("It's not supported yet");
    }

    /** {@inheritDoc} */
    @Override public void writeExternal(ObjectOutput out) throws IOException {
        // No-op
    }

    /** {@inheritDoc} */
    @Override public void readExternal(ObjectInput in) throws IOException, ClassNotFoundException {
        // No-op
    }

    /** {@inheritDoc} */
    @Override public boolean equals(Object obj) {
        if (this == obj)
            return true;

        if (obj == null || getClass() != obj.getClass())
            return false;

        return true;
    }
}