com.cloudera.oryx.app.classreg.example.Example.java Source code

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/*
 * Copyright (c) 2014, Cloudera, Inc. All Rights Reserved.
 *
 * Cloudera, Inc. 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
 *
 * This software 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 com.cloudera.oryx.app.classreg.example;

import java.io.Serializable;
import java.util.Arrays;
import java.util.Objects;

import com.google.common.base.Preconditions;
import com.google.common.hash.HashFunction;
import com.google.common.hash.Hasher;
import com.google.common.hash.Hashing;

/**
 * Encapsulates one example, or data point: a set of features that predict a target feature.
 * Some features may be missing, and in the case of test examples, the target value may be
 * missing or unknown.
 */
public final class Example implements Serializable {

    private static final HashFunction HASH = Hashing.goodFastHash(32);

    private final Feature[] features;
    private final Feature target;
    private final int cachedHashCode;

    public Example(Feature target, Feature... features) {
        Preconditions.checkArgument(features != null);
        this.features = features;
        this.target = target;
        Hasher hasher = HASH.newHasher();
        for (Feature feature : features) {
            if (feature != null) {
                hasher.putInt(feature.hashCode());
            }
        }
        if (target != null) {
            hasher.putInt(target.hashCode());
        }
        cachedHashCode = hasher.hashCode();
    }

    public Feature getFeature(int i) {
        return features[i];
    }

    public Feature getTarget() {
        return target;
    }

    @Override
    public boolean equals(Object o) {
        if (!(o instanceof Example)) {
            return false;
        }
        Example other = (Example) o;
        return Arrays.equals(features, other.features) && Objects.equals(target, other.target);
    }

    @Override
    public int hashCode() {
        return cachedHashCode;
    }

    @Override
    public String toString() {
        return target == null ? Arrays.toString(features) : Arrays.toString(features) + " -> " + target;
    }

}