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Java example source code file (CurvesDataFetcher.java)

This example Java source code file (CurvesDataFetcher.java) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

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Java - Java tags/keywords

basedatafetcher, could, curves_file_name, curves_url, curvesdatafetcher, dataset, downloading, fetched, file, ioexception, local_dir_name, net, network, override, string

The CurvesDataFetcher.java Java example source code

 *  * Copyright 2015 Skymind,Inc.
 *  *
 *  *    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.deeplearning4j.datasets.fetchers;

import org.apache.commons.io.FileUtils;

import org.nd4j.linalg.dataset.DataSet;
import org.nd4j.linalg.indexing.NDArrayIndex;
import org.deeplearning4j.util.SerializationUtils;
import org.nd4j.linalg.util.ArrayUtil;

import java.io.File;
import java.io.IOException;
import java.net.URL;

 * Curves data fetcher
 * @author Adam Gibson
public class CurvesDataFetcher extends BaseDataFetcher {

    public final static String CURVES_URL = "https://s3.amazonaws.com/dl4j-distribution/curves.ser";
    public final static String LOCAL_DIR_NAME =  "curves";
    public final static String CURVES_FILE_NAME = "curves.ser";
    private DataSet data;

    public CurvesDataFetcher() throws IOException {
        totalExamples = data.numExamples();


    private void download() throws IOException {
        // mac gives unique tmp each run and we want to store this persist
        // this data across restarts
        File tmpDir = new File(System.getProperty("user.home"));

        File baseDir = new File(tmpDir, LOCAL_DIR_NAME);
        if(!(baseDir.isDirectory() || baseDir.mkdir())) {
            throw new IOException("Could not mkdir " + baseDir);

        File dataFile = new File(baseDir,CURVES_FILE_NAME);

        if(!dataFile.exists() || !dataFile.isFile()) {
            log.info("Downloading curves dataset...");
            FileUtils.copyURLToFile(new URL(CURVES_URL), dataFile);

        data = SerializationUtils.readObject(dataFile);


    public boolean hasMore() {
        return super.hasMore();

     * Fetches the next dataset. You need to call this
     * to getFromOrigin a new dataset, otherwise {@link #next()}
     * just returns the last data applyTransformToDestination fetch
     * @param numExamples the number of examples to fetch
    public void fetch(int numExamples) {
        if(cursor >= data.numExamples()) {
            cursor = data.numExamples();

        curr = data.get(ArrayUtil.range(cursor, cursor + numExamples));
        log.info("Fetched " + curr.numExamples());
        if(cursor + numExamples < data.numExamples())
            cursor += numExamples;
        //always stay at the end
        else if(cursor + numExamples > data.numExamples())
            cursor = data.numExamples()  -1;


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