com.davidbracewell.ml.utils.DataSets.java Source code

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Here is the source code for com.davidbracewell.ml.utils.DataSets.java

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/*
 * (c) 2005 David B. Bracewell
 *
 * 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 com.davidbracewell.ml.utils;

import com.davidbracewell.tuple.Pair;
import com.google.common.base.Preconditions;
import com.google.common.collect.Lists;

import java.util.List;

/**
 * The type Data sets.
 *
 * @author David B. Bracewell
 */
public class DataSets {

    private static <TrainType> void addAll(List<TrainType> list, List<List<TrainType>> listOfLists) {
        for (List<TrainType> l : listOfLists) {
            list.addAll(l);
        }
    }

    public static <TrainType> Pair<List<TrainType>, List<TrainType>> createTrainTest(List<List<TrainType>> folds,
            int i) {
        List<TrainType> train = Lists.newArrayList();
        List<TrainType> test = Lists.newArrayList(folds.get(i));
        if (i == 0) {
            addAll(train, folds.subList(1, folds.size()));
        } else if (i == folds.size() - 1) {
            addAll(train, folds.subList(0, folds.size() - 1));
        } else {
            addAll(train, folds.subList(0, i));
            addAll(train, folds.subList(i + 1, folds.size()));
        }
        return Pair.of(train, test);
    }

    /**
     * Split pair.
     *
     * @param data            the data
     * @param trainPercentage the train percentage
     * @return the pair
     */
    public static <V> Pair<List<V>, List<V>> split(List<V> data, double trainPercentage) {
        Preconditions.checkNotNull(data);
        Preconditions.checkArgument(data.size() > 1, "Must be at least 2 items in the data set.");
        Preconditions.checkArgument(trainPercentage > 0, "Training percentage must be > 0.");
        int index = (int) Math.floor((double) data.size() * trainPercentage);
        return Pair.of(data.subList(0, index), data.subList(index, data.size()));
    }

    /**
     * Create folds.
     *
     * @param data     the data
     * @param numFolds the num folds
     * @return the list
     */
    public static <V> List<List<V>> nFolds(List<V> data, int numFolds) {
        Preconditions.checkNotNull(data);
        Preconditions.checkArgument(numFolds > 1, "Must be at least two folds.");
        Preconditions.checkArgument(data.size() >= numFolds,
                "Must be at least number of fold items in the data set.");
        return Lists.partition(data, (int) Math.floor((double) data.size() / numFolds));
    }

}//END OF DataSets