Java tutorial
/* * 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.mahout.classifier.bayes; import java.io.BufferedReader; import java.io.IOException; import java.io.InputStreamReader; import java.io.OutputStreamWriter; import java.io.Writer; import java.nio.charset.Charset; import java.util.BitSet; import com.google.common.base.Charsets; import com.google.common.base.Preconditions; import org.apache.commons.cli2.CommandLine; import org.apache.commons.cli2.Group; import org.apache.commons.cli2.Option; import org.apache.commons.cli2.OptionException; import org.apache.commons.cli2.builder.ArgumentBuilder; import org.apache.commons.cli2.builder.DefaultOptionBuilder; import org.apache.commons.cli2.builder.GroupBuilder; import org.apache.commons.cli2.commandline.Parser; import org.apache.hadoop.conf.Configuration; import org.apache.hadoop.fs.FileStatus; import org.apache.hadoop.fs.FileSystem; import org.apache.hadoop.fs.Path; import org.apache.mahout.common.CommandLineUtil; import org.apache.mahout.common.IOUtils; import org.apache.mahout.common.RandomUtils; import org.apache.mahout.common.commandline.DefaultOptionCreator; import org.apache.mahout.math.jet.random.sampling.RandomSampler; import org.slf4j.Logger; import org.slf4j.LoggerFactory; /** * A utility for splitting files in the input format used by the Bayes * classifiers into training and test sets in order to perform cross-validation. * This class is not strictly confined to working with the Bayes classifier * input. It can be used for any input files where each line is a complete * sample. * <p> * This class can be used to split directories of files or individual files into * training and test sets using a number of different methods. * <p> * When executed via {@link #splitDirectory(Path)} or {@link #splitFile(Path)}, * the lines read from one or more, input files are written to files of the same * name into the directories specified by the * {@link #setTestOutputDirectory(Path)} and * {@link #setTrainingOutputDirectory(Path)} methods. * <p> * The composition of the test set is determined using one of the following * approaches: * <ul> * <li>A contiguous set of items can be chosen from the input file(s) using the * {@link #setTestSplitSize(int)} or {@link #setTestSplitPct(int)} methods. * {@link #setTestSplitSize(int)} allocates a fixed number of items, while * {@link #setTestSplitPct(int)} allocates a percentage of the original input, * rounded up to the nearest integer. {@link #setSplitLocation(int)} is used to * control the position in the input from which the test data is extracted and * is described further below.</li> * <li>A random sampling of items can be chosen from the input files(s) using * the {@link #setTestRandomSelectionSize(int)} or * {@link #setTestRandomSelectionPct(int)} methods, each choosing a fixed test * set size or percentage of the input set size as described above. The * {@link RandomSampler} class from {@code mahout-math} is used to create a sample * of the appropriate size.</li> * </ul> * <p> * Any one of the methods above can be used to control the size of the test set. * If multiple methods are called, a runtime exception will be thrown at * execution time. * <p> * The {@link #setSplitLocation(int)} method is passed an integer from 0 to 100 * (inclusive) which is translated into the position of the start of the test * data within the input file. * <p> * Given: * <ul> * <li>an input file of 1500 lines</li> * <li>a desired test data size of 10 percent</li> * </ul> * <p> * <ul> * <li>A split location of 0 will cause the first 150 items appearing in the * input set to be written to the test set.</li> * <li>A split location of 25 will cause items 375-525 to be written to the test * set.</li> * <li>A split location of 100 will cause the last 150 items in the input to be * written to the test set</li> * </ul> * The start of the split will always be adjusted forwards in order to ensure * that the desired test set size is allocated. Split location has no effect is * random sampling is employed. */ public class SplitBayesInput { private static final Logger log = LoggerFactory.getLogger(SplitBayesInput.class); private int testSplitSize = -1; private int testSplitPct = -1; private int splitLocation = 100; private int testRandomSelectionSize = -1; private int testRandomSelectionPct = -1; private Charset charset = Charsets.UTF_8; private final FileSystem fs; private Path inputDirectory; private Path trainingOutputDirectory; private Path testOutputDirectory; private SplitCallback callback; public static void main(String[] args) throws Exception { SplitBayesInput si = new SplitBayesInput(); if (si.parseArgs(args)) { si.splitDirectory(); } } public SplitBayesInput() throws IOException { Configuration conf = new Configuration(); fs = FileSystem.get(conf); } /** Configure this instance based on the command-line arguments contained within provided array. * Calls {@link #validate()} to ensure consistency of configuration. * * @return true if the arguments were parsed successfully and execution should proceed. * @throws Exception if there is a problem parsing the command-line arguments or the particular * combination would violate class invariants. */ public boolean parseArgs(String[] args) throws Exception { DefaultOptionBuilder obuilder = new DefaultOptionBuilder(); ArgumentBuilder abuilder = new ArgumentBuilder(); GroupBuilder gbuilder = new GroupBuilder(); Option helpOpt = DefaultOptionCreator.helpOption(); Option inputDirOpt = obuilder.withLongName("inputDir").withRequired(true) .withArgument(abuilder.withName("inputDir").withMinimum(1).withMaximum(1).create()) .withDescription("The input directory").withShortName("i").create(); Option trainingOutputDirOpt = obuilder.withLongName("trainingOutputDir").withRequired(true) .withArgument(abuilder.withName("outputDir").withMinimum(1).withMaximum(1).create()) .withDescription("The training data output directory").withShortName("tr").create(); Option testOutputDirOpt = obuilder.withLongName("testOutputDir").withRequired(true) .withArgument(abuilder.withName("outputDir").withMinimum(1).withMaximum(1).create()) .withDescription("The test data output directory").withShortName("te").create(); Option testSplitSizeOpt = obuilder.withLongName("testSplitSize").withRequired(false) .withArgument(abuilder.withName("splitSize").withMinimum(1).withMaximum(1).create()) .withDescription("The number of documents held back as test data for each category") .withShortName("ss").create(); Option testSplitPctOpt = obuilder.withLongName("testSplitPct").withRequired(false) .withArgument(abuilder.withName("splitPct").withMinimum(1).withMaximum(1).create()) .withDescription("The percentage of documents held back as test data for each category") .withShortName("sp").create(); Option splitLocationOpt = obuilder.withLongName("splitLocation").withRequired(false) .withArgument(abuilder.withName("splitLoc").withMinimum(1).withMaximum(1).create()) .withDescription( "Location for start of test data expressed as a percentage of the input file size (0=start, 50=middle, 100=end") .withShortName("sl").create(); Option randomSelectionSizeOpt = obuilder.withLongName("randomSelectionSize").withRequired(false) .withArgument(abuilder.withName("randomSize").withMinimum(1).withMaximum(1).create()) .withDescription("The number of itemr to be randomly selected as test data ").withShortName("rs") .create(); Option randomSelectionPctOpt = obuilder.withLongName("randomSelectionPct").withRequired(false) .withArgument(abuilder.withName("randomPct").withMinimum(1).withMaximum(1).create()) .withDescription("Percentage of items to be randomly selected as test data ").withShortName("rp") .create(); Option charsetOpt = obuilder.withLongName("charset").withRequired(true) .withArgument(abuilder.withName("charset").withMinimum(1).withMaximum(1).create()) .withDescription("The name of the character encoding of the input files").withShortName("c") .create(); Group group = gbuilder.withName("Options").withOption(inputDirOpt).withOption(trainingOutputDirOpt) .withOption(testOutputDirOpt).withOption(testSplitSizeOpt).withOption(testSplitPctOpt) .withOption(splitLocationOpt).withOption(randomSelectionSizeOpt).withOption(randomSelectionPctOpt) .withOption(charsetOpt).create(); try { Parser parser = new Parser(); parser.setGroup(group); CommandLine cmdLine = parser.parse(args); if (cmdLine.hasOption(helpOpt)) { CommandLineUtil.printHelp(group); return false; } inputDirectory = new Path((String) cmdLine.getValue(inputDirOpt)); trainingOutputDirectory = new Path((String) cmdLine.getValue(trainingOutputDirOpt)); testOutputDirectory = new Path((String) cmdLine.getValue(testOutputDirOpt)); charset = Charset.forName((String) cmdLine.getValue(charsetOpt)); if (cmdLine.hasOption(testSplitSizeOpt) && cmdLine.hasOption(testSplitPctOpt)) { throw new OptionException(testSplitSizeOpt, "must have either split size or split percentage option, not BOTH"); } else if (!cmdLine.hasOption(testSplitSizeOpt) && !cmdLine.hasOption(testSplitPctOpt)) { throw new OptionException(testSplitSizeOpt, "must have either split size or split percentage option"); } if (cmdLine.hasOption(testSplitSizeOpt)) { setTestSplitSize(Integer.parseInt((String) cmdLine.getValue(testSplitSizeOpt))); } if (cmdLine.hasOption(testSplitPctOpt)) { setTestSplitPct(Integer.parseInt((String) cmdLine.getValue(testSplitPctOpt))); } if (cmdLine.hasOption(splitLocationOpt)) { setSplitLocation(Integer.parseInt((String) cmdLine.getValue(splitLocationOpt))); } if (cmdLine.hasOption(randomSelectionSizeOpt)) { setTestRandomSelectionSize(Integer.parseInt((String) cmdLine.getValue(randomSelectionSizeOpt))); } if (cmdLine.hasOption(randomSelectionPctOpt)) { setTestRandomSelectionPct(Integer.parseInt((String) cmdLine.getValue(randomSelectionPctOpt))); } fs.mkdirs(trainingOutputDirectory); fs.mkdirs(testOutputDirectory); } catch (OptionException e) { log.error("Command-line option Exception", e); CommandLineUtil.printHelp(group); return false; } validate(); return true; } /** Perform a split on directory specified by {@link #setInputDirectory(Path)} by calling {@link #splitFile(Path)} * on each file found within that directory. */ public void splitDirectory() throws IOException { this.splitDirectory(inputDirectory); } /** Perform a split on the specified directory by calling {@link #splitFile(Path)} on each file found within that * directory. */ public void splitDirectory(Path inputDir) throws IOException { if (fs.getFileStatus(inputDir) == null) { throw new IOException(inputDir + " does not exist"); } else if (!fs.getFileStatus(inputDir).isDir()) { throw new IOException(inputDir + " is not a directory"); } // input dir contains one file per category. FileStatus[] fileStats = fs.listStatus(inputDir); for (FileStatus inputFile : fileStats) { if (!inputFile.isDir()) { splitFile(inputFile.getPath()); } } } /** Perform a split on the specified input file. Results will be written to files of the same name in the specified * training and test output directories. The {@link #validate()} method is called prior to executing the split. */ public void splitFile(Path inputFile) throws IOException { if (fs.getFileStatus(inputFile) == null) { throw new IOException(inputFile + " does not exist"); } else if (fs.getFileStatus(inputFile).isDir()) { throw new IOException(inputFile + " is a directory"); } validate(); Path testOutputFile = new Path(testOutputDirectory, inputFile.getName()); Path trainingOutputFile = new Path(trainingOutputDirectory, inputFile.getName()); int lineCount = countLines(fs, inputFile, charset); log.info("{} has {} lines", inputFile.getName(), lineCount); int testSplitStart = 0; int testSplitSize = this.testSplitSize; // don't modify state BitSet randomSel = null; if (testRandomSelectionPct > 0 || testRandomSelectionSize > 0) { testSplitSize = this.testRandomSelectionSize; if (testRandomSelectionPct > 0) { testSplitSize = Math.round(lineCount * testRandomSelectionPct / 100.0f); } log.info("{} test split size is {} based on random selection percentage {}", new Object[] { inputFile.getName(), testSplitSize, testRandomSelectionPct }); long[] ridx = new long[testSplitSize]; RandomSampler.sample(testSplitSize, lineCount - 1, testSplitSize, 0, ridx, 0, RandomUtils.getRandom()); randomSel = new BitSet(lineCount); for (long idx : ridx) { randomSel.set((int) idx + 1); } } else { if (testSplitPct > 0) { // calculate split size based on percentage testSplitSize = Math.round(lineCount * testSplitPct / 100.0f); log.info("{} test split size is {} based on percentage {}", new Object[] { inputFile.getName(), testSplitSize, testSplitPct }); } else { log.info("{} test split size is {}", inputFile.getName(), testSplitSize); } if (splitLocation > 0) { // calculate start of split based on percentage testSplitStart = Math.round(lineCount * splitLocation / 100.0f); if (lineCount - testSplitStart < testSplitSize) { // adjust split start downwards based on split size. testSplitStart = lineCount - testSplitSize; } log.info("{} test split start is {} based on split location {}", new Object[] { inputFile.getName(), testSplitStart, splitLocation }); } if (testSplitStart < 0) { throw new IllegalArgumentException( "test split size for " + inputFile + " is too large, it would produce an " + "empty training set from the initial set of " + lineCount + " examples"); } else if (lineCount - testSplitSize < testSplitSize) { log.warn( "Test set size for {} may be too large, {} is larger than the number of " + "lines remaining in the training set: {}", new Object[] { inputFile, testSplitSize, lineCount - testSplitSize }); } } BufferedReader reader = new BufferedReader(new InputStreamReader(fs.open(inputFile), charset)); Writer trainingWriter = new OutputStreamWriter(fs.create(trainingOutputFile), charset); Writer testWriter = new OutputStreamWriter(fs.create(testOutputFile), charset); int trainCount = 0; int testCount = 0; try { String line; int pos = 0; while ((line = reader.readLine()) != null) { pos++; Writer writer; if (testRandomSelectionPct > 0) { // Randomly choose writer = randomSel.get(pos) ? testWriter : trainingWriter; } else { // Choose based on location writer = pos > testSplitStart ? testWriter : trainingWriter; } if (writer == testWriter) { if (testCount >= testSplitSize) { writer = trainingWriter; } else { testCount++; } } if (writer == trainingWriter) { trainCount++; } writer.write(line); writer.write('\n'); } } finally { IOUtils.quietClose(reader); IOUtils.quietClose(trainingWriter); IOUtils.quietClose(testWriter); } log.info("file: {}, input: {} train: {}, test: {} starting at {}", new Object[] { inputFile.getName(), lineCount, trainCount, testCount, testSplitStart }); // testing; if (callback != null) { callback.splitComplete(inputFile, lineCount, trainCount, testCount, testSplitStart); } } public int getTestSplitSize() { return testSplitSize; } public void setTestSplitSize(int testSplitSize) { this.testSplitSize = testSplitSize; } public int getTestSplitPct() { return testSplitPct; } /** Sets the percentage of the input data to allocate to the test split * * @param testSplitPct * a value between 0 and 100 inclusive. */ public void setTestSplitPct(int testSplitPct) { this.testSplitPct = testSplitPct; } public int getSplitLocation() { return splitLocation; } /** Set the location of the start of the test/training data split. Expressed as percentage of lines, for example * 0 indicates that the test data should be taken from the start of the file, 100 indicates that the test data * should be taken from the end of the input file, while 25 indicates that the test data should be taken from the * first quarter of the file. * <p> * This option is only relevant in cases where random selection is not employed * * @param splitLocation * a value between 0 and 100 inclusive. */ public void setSplitLocation(int splitLocation) { this.splitLocation = splitLocation; } public Charset getCharset() { return charset; } /** Set the charset used to read and write files */ public void setCharset(Charset charset) { this.charset = charset; } public Path getInputDirectory() { return inputDirectory; } /** Set the directory from which input data will be read when the the {@link #splitDirectory()} method is invoked */ public void setInputDirectory(Path inputDir) { this.inputDirectory = inputDir; } public Path getTrainingOutputDirectory() { return trainingOutputDirectory; } /** Set the directory to which training data will be written. */ public void setTrainingOutputDirectory(Path trainingOutputDir) { this.trainingOutputDirectory = trainingOutputDir; } public Path getTestOutputDirectory() { return testOutputDirectory; } /** Set the directory to which test data will be written. */ public void setTestOutputDirectory(Path testOutputDir) { this.testOutputDirectory = testOutputDir; } public SplitCallback getCallback() { return callback; } /** Sets the callback used to inform the caller that an input file has been successfully split */ public void setCallback(SplitCallback callback) { this.callback = callback; } public int getTestRandomSelectionSize() { return testRandomSelectionSize; } /** Sets number of random input samples that will be saved to the test set. */ public void setTestRandomSelectionSize(int testRandomSelectionSize) { this.testRandomSelectionSize = testRandomSelectionSize; } public int getTestRandomSelectionPct() { return testRandomSelectionPct; } /** Sets number of random input samples that will be saved to the test set as a percentage of the size of the * input set. * * @param randomSelectionPct a value between 0 and 100 inclusive. */ public void setTestRandomSelectionPct(int randomSelectionPct) { this.testRandomSelectionPct = randomSelectionPct; } /** Validates that the current instance is in a consistent state * * @throws IllegalArgumentException * if settings violate class invariants. * @throws IOException * if output directories do not exist or are not directories. */ public void validate() throws IOException { Preconditions.checkArgument(testSplitSize >= 1 || testSplitSize == -1, "Invalid testSplitSize", testSplitSize); Preconditions.checkArgument(splitLocation >= 0 && splitLocation <= 100 || splitLocation == -1, "Invalid splitLocation percentage", splitLocation); Preconditions.checkArgument(testSplitPct >= 0 && testSplitPct <= 100 || testSplitPct == -1, "Invalid testSplitPct percentage", testSplitPct); Preconditions.checkArgument(splitLocation >= 0 && splitLocation <= 100 || splitLocation == -1, "Invalid splitLocation percentage", splitLocation); Preconditions.checkArgument( testRandomSelectionPct >= 0 && testRandomSelectionPct <= 100 || testRandomSelectionPct == -1, "Invalid testRandomSelectionPct percentage", testRandomSelectionPct); Preconditions.checkArgument(trainingOutputDirectory != null, "No training output directory was specified"); Preconditions.checkArgument(testOutputDirectory != null, "No test output directory was specified"); // only one of the following may be set, one must be set. int count = 0; if (testSplitSize > 0) { count++; } if (testSplitPct > 0) { count++; } if (testRandomSelectionSize > 0) { count++; } if (testRandomSelectionPct > 0) { count++; } Preconditions.checkArgument(count == 1, "Exactly one of testSplitSize, testSplitPct, testRandomSelectionSize, testRandomSelectionPct should be set"); FileStatus trainingOutputDirStatus = fs.getFileStatus(trainingOutputDirectory); Preconditions.checkArgument(trainingOutputDirStatus != null && trainingOutputDirStatus.isDir(), "%s is not a directory", trainingOutputDirectory); FileStatus testOutputDirStatus = fs.getFileStatus(testOutputDirectory); Preconditions.checkArgument(testOutputDirStatus != null && testOutputDirStatus.isDir(), "%s is not a directory", testOutputDirectory); } /** * Count the lines in the file specified as returned by {@code BufferedReader.readLine()} * * @param inputFile * the file whose lines will be counted * * @param charset * the charset of the file to read * * @return the number of lines in the input file. * * @throws IOException * if there is a problem opening or reading the file. */ public static int countLines(FileSystem fs, Path inputFile, Charset charset) throws IOException { int lineCount = 0; BufferedReader countReader = new BufferedReader(new InputStreamReader(fs.open(inputFile), charset)); try { while (countReader.readLine() != null) { lineCount++; } } finally { IOUtils.quietClose(countReader); } return lineCount; } /** Used to pass information back to a caller once a file has been split without the need for a data object */ public interface SplitCallback { void splitComplete(Path inputFile, int lineCount, int trainCount, int testCount, int testSplitStart); } }