SAMOA-43: Add TextReader
diff --git a/samoa-api/src/main/java/org/apache/samoa/streams/TextGenerator.java b/samoa-api/src/main/java/org/apache/samoa/streams/TextGenerator.java
new file mode 100644
index 0000000..c165f33
--- /dev/null
+++ b/samoa-api/src/main/java/org/apache/samoa/streams/TextGenerator.java
@@ -0,0 +1,205 @@
+package org.apache.samoa.streams;
+
+/*
+ * #%L
+ * SAMOA
+ * %%
+ * Copyright (C) 2014 - 2015 Apache Software Foundation
+ * %%
+ * 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.
+ * #L%
+ */
+
+import com.github.javacliparser.IntOption;
+import org.apache.samoa.instances.*;
+import org.apache.samoa.moa.core.InstanceExample;
+import org.apache.samoa.moa.core.ObjectRepository;
+import org.apache.samoa.moa.options.AbstractOptionHandler;
+import org.apache.samoa.moa.streams.InstanceStream;
+import org.apache.samoa.moa.tasks.TaskMonitor;
+
+import java.util.ArrayList;
+import java.util.Random;
+
+/**
+ * Text generator that simulates sentiment analysis on tweets.
+ */
+public class TextGenerator extends AbstractOptionHandler implements InstanceStream {
+
+ private static final long serialVersionUID = 3028905554604259131L;
+
+ public IntOption numAttsOption = new IntOption("numAtts", 'a',
+ "The number of attributes to generate.", 1000, 0, Integer.MAX_VALUE);
+
+ public IntOption instanceRandomSeedOption = new IntOption(
+ "instanceRandomSeed", 'i',
+ "Seed for random generation of instances.", 1);
+
+ protected InstancesHeader streamHeader;
+
+ protected Random instanceRandom;
+
+ protected int[] wordTwitterGenerator;
+ protected double[] freqTwitterGenerator;
+ protected double[] sumFreqTwitterGenerator;
+ protected int[] classTwitterGenerator;
+
+ protected int sizeTable;
+ protected double probPositive = 0.1;
+ protected double probNegative = 0.1;
+ protected double zipfExponent = 1.5;
+ protected double lengthTweet = 15;
+
+ protected int countTweets = 0;
+
+ @Override
+ public InstancesHeader getHeader() {
+ return this.streamHeader;
+ }
+
+ @Override
+ public long estimatedRemainingInstances() {
+ return -1;
+ }
+
+ @Override
+ public boolean hasMoreInstances() {
+ return true;
+ }
+
+ @Override
+ public InstanceExample nextInstance() {
+ int[] votes;
+ double[] attVals;
+ attVals = new double[this.numAttsOption.getValue() + 1];
+
+ do {
+ int length = (int) (lengthTweet * (1.0 + this.instanceRandom.nextGaussian()));
+ if (length < 1) length = 1;
+ votes = new int[3];
+ for (int j = 0; j < length; j++) {
+ double rand = this.instanceRandom.nextDouble();
+ //binary search
+ int i = 0;
+ int min = 0;
+ int max = sizeTable - 1;
+ int mid;
+ do {
+ mid = (min + max) / 2;
+ if (rand > this.sumFreqTwitterGenerator[mid]) {
+ min = mid + 1;
+ } else {
+ max = mid - 1;
+ }
+ } while ((this.sumFreqTwitterGenerator[mid] != rand) && (min <= max));
+
+ attVals[this.wordTwitterGenerator[mid]] = 1;
+ votes[this.classTwitterGenerator[mid]]++;
+
+ }
+ } while (votes[1] == votes[2]);
+
+ Instance inst = new DenseInstance(1.0, attVals);
+ inst.setDataset(getHeader());
+ inst.setClassValue((votes[1] > votes[2]) ? 0 : 1);
+ this.countTweets++;
+ return new InstanceExample(inst);
+ }
+
+ @Override
+ public boolean isRestartable() {
+ return true;
+ }
+
+ @Override
+ public void restart() {
+
+ this.sizeTable = this.numAttsOption.getValue();
+
+ //Prepare table of words to generate tweets
+ this.wordTwitterGenerator = new int[sizeTable];
+ this.freqTwitterGenerator = new double[sizeTable];
+ this.sumFreqTwitterGenerator = new double[sizeTable];
+ this.classTwitterGenerator = new int[sizeTable];
+
+ this.countTweets = 0;
+
+ double sum = 0;
+ this.instanceRandom = new Random(this.instanceRandomSeedOption.getValue());
+ for (int i = 0; i < this.sizeTable; i++) {
+ this.wordTwitterGenerator[i] = i + 1;
+ this.freqTwitterGenerator[i] = 1.0 / Math.pow(i + 1, zipfExponent);
+ sum += this.freqTwitterGenerator[i];
+ this.sumFreqTwitterGenerator[i] = sum;
+ double rand = this.instanceRandom.nextDouble();
+ this.classTwitterGenerator[i] = (rand < probPositive ? 1 : (rand < probNegative + probPositive ? 2 : 0));
+ }
+ for (int i = 0; i < this.sizeTable; i++) {
+ this.freqTwitterGenerator[i] /= sum;
+ this.sumFreqTwitterGenerator[i] /= sum;
+ }
+
+ }
+
+ @Override
+ protected void prepareForUseImpl(TaskMonitor monitor, ObjectRepository repository) {
+ generateHeader();
+ restart();
+ }
+
+ @Override
+ public void getDescription(StringBuilder sb, int indent) {
+
+ }
+ private void generateHeader() {
+ ArrayList<Attribute> attributes = new ArrayList();
+ for (int i = 0; i < this.numAttsOption.getValue(); i++) {
+ attributes.add(new Attribute("att" + (i + 1)));
+ }
+ ArrayList<String> classLabels = new ArrayList();
+ for (int i = 0; i < 2; i++) {
+ classLabels.add("class" + (i + 1));
+ }
+ attributes.add(new Attribute("class", classLabels));
+ this.streamHeader = new InstancesHeader(new Instances(
+ getCLICreationString(InstanceStream.class), attributes, 0));
+ this.streamHeader.setClassIndex(this.streamHeader.numAttributes() - 1);
+ }
+
+
+ public void changePolarity(int numberWords) {
+ for (int i = 0; i < numberWords; ) {
+ int randWord = this.instanceRandom.nextInt(this.sizeTable);
+ int polarity = this.classTwitterGenerator[randWord];
+ if (polarity == 1) {
+ this.classTwitterGenerator[i] = 2;
+ i++;
+ }
+ if (polarity == 2) {
+ this.classTwitterGenerator[i] = 1;
+ i++;
+ }
+ }
+ }
+
+ public void changeFreqWords(int numberWords) {
+ for (int i = 0; i < numberWords; i++) {
+ int randWordTo = this.instanceRandom.nextInt(this.sizeTable);
+ int randWordFrom = this.instanceRandom.nextInt(this.sizeTable);
+ this.wordTwitterGenerator[randWordTo] = randWordFrom;
+ this.wordTwitterGenerator[randWordFrom] = randWordTo;
+ }
+ }
+
+
+}
