1 | // Copyright 2012 Georg-August-Universität Göttingen, Germany |
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2 | // |
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3 | // Licensed under the Apache License, Version 2.0 (the "License"); |
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4 | // you may not use this file except in compliance with the License. |
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5 | // You may obtain a copy of the License at |
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6 | // |
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7 | // http://www.apache.org/licenses/LICENSE-2.0 |
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8 | // |
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9 | // Unless required by applicable law or agreed to in writing, software |
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10 | // distributed under the License is distributed on an "AS IS" BASIS, |
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11 | // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
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12 | // See the License for the specific language governing permissions and |
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13 | // limitations under the License. |
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14 | |
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15 | package de.ugoe.cs.autoquest.testgeneration; |
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16 | |
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17 | import java.util.ArrayList; |
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18 | import java.util.Collection; |
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19 | import java.util.LinkedHashSet; |
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20 | import java.util.LinkedList; |
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21 | import java.util.List; |
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22 | import java.util.Random; |
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23 | import java.util.logging.Level; |
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24 | |
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25 | import de.ugoe.cs.autoquest.eventcore.Event; |
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26 | import de.ugoe.cs.autoquest.usageprofiles.IStochasticProcess; |
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27 | import de.ugoe.cs.util.console.Console; |
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28 | |
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29 | /** |
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30 | * <p> |
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31 | * Generates a test suite with a hybrid approach that is a mixture of random walks and drawing from |
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32 | * all possible sequences. |
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33 | * </p> |
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34 | * |
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35 | * @author Steffen Herbold |
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36 | * @version 1.0 |
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37 | */ |
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38 | public class HybridGenerator { |
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39 | |
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40 | /** |
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41 | * <p> |
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42 | * Number of sequences in the test suite. |
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43 | * </p> |
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44 | */ |
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45 | private final int numSequences; |
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46 | |
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47 | /** |
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48 | * <p> |
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49 | * Length of a test sequence. |
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50 | * </p> |
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51 | */ |
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52 | private final int length; |
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53 | |
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54 | /** |
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55 | * <p> |
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56 | * Maximal length where it is possible to generate all sequences and draw from them. |
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57 | * </p> |
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58 | */ |
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59 | private final int maxLengthAll; |
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60 | |
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61 | /** |
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62 | * <p> |
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63 | * In case this member is true, only test cases that end in the global end event |
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64 | * {@link Event#ENDEVENT} are generated. If it is false, the end event can be any event. |
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65 | * </p> |
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66 | */ |
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67 | private final boolean validEnd; |
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68 | |
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69 | /** |
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70 | * <p> |
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71 | * Constructor. Creates a new HybridGenerator and ensures the validity of the parameters: |
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72 | * <ul> |
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73 | * <li>numSequences must at least be 1 |
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74 | * <li>length must be at least 1 |
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75 | * </ul> |
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76 | * If one of these conditions is violated an {@link IllegalArgumentException} is thrown. |
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77 | * </p> |
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78 | * |
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79 | * @param numSequences |
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80 | * number of sequences desired for the test suite |
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81 | * @param length |
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82 | * length of a test sequence |
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83 | * @param maxLengthAll |
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84 | * maximal length where it is possible to generate all sequences and draw from them |
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85 | * @param validEnd |
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86 | * defines if test cases have to end with the global end event {@link Event#ENDEVENT} |
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87 | * (see {@link #validEnd}) |
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88 | */ |
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89 | public HybridGenerator(int numSequences, int length, int maxLengthAll, boolean validEnd) { |
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90 | // check validity of the parameters |
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91 | if (numSequences < 1) { |
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92 | throw new IllegalArgumentException("number of sequences must be at least 1 but is " + |
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93 | numSequences); |
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94 | } |
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95 | if (length < 1) { |
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96 | throw new IllegalArgumentException("length of test cases must be at least 1 but is " + |
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97 | length); |
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98 | } |
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99 | this.numSequences = numSequences; |
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100 | this.length = length; |
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101 | this.maxLengthAll = maxLengthAll; |
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102 | this.validEnd = validEnd; |
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103 | } |
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104 | |
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105 | /** |
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106 | * <p> |
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107 | * Generates a test suite with a hybrid approach that is a mixture of random walks and drawing |
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108 | * from all possible sequences |
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109 | * </p> |
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110 | * |
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111 | * @param model |
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112 | * model used to determine the probability of each possible sequence |
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113 | * @return the test suite |
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114 | */ |
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115 | public Collection<List<Event>> generateTestSuite(IStochasticProcess model) { |
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116 | if (model == null) { |
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117 | throw new IllegalArgumentException("model must not be null!"); |
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118 | } |
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119 | |
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120 | Collection<List<Event>> sequences = new LinkedHashSet<List<Event>>(); |
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121 | |
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122 | List<List<Event>> seqsTmp = |
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123 | new ArrayList<List<Event>>(model.generateSequences(maxLengthAll + 1, true)); |
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124 | |
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125 | Console.traceln(Level.INFO, "" + seqsTmp.size() + " of length " + maxLengthAll + " possible"); |
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126 | List<Double> probabilities = new ArrayList<Double>(seqsTmp.size()); |
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127 | double probSum = 0.0; |
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128 | for (List<Event> sequence : seqsTmp) { |
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129 | double prob = model.getProbability(sequence); |
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130 | probabilities.add(prob); |
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131 | probSum += prob; |
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132 | } |
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133 | |
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134 | Random r = new Random(); |
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135 | int j = 0; |
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136 | while (sequences.size() < numSequences && j <= numSequences * 100) { |
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137 | j++; |
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138 | double randVal = r.nextDouble() * probSum; |
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139 | double sum = 0.0d; |
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140 | int index = -1; |
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141 | while (sum < randVal) { |
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142 | index++; |
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143 | double currentProb = probabilities.get(index); |
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144 | sum += currentProb; |
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145 | } |
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146 | List<Event> seqTmp = seqsTmp.get(index); |
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147 | if (!Event.ENDEVENT.equals(seqTmp.get(seqTmp.size() - 1))) { |
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148 | List<Event> sequence; |
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149 | if (validEnd) { |
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150 | sequence = finishSequence(seqTmp, model, length + 2, validEnd); |
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151 | if (sequence != null && sequence.size() != length + 2) { |
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152 | sequence = null; |
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153 | } |
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154 | } |
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155 | else { |
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156 | sequence = finishSequence(seqTmp, model, length + 1, validEnd); |
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157 | if (sequence != null && sequence.size() != length + 1) { |
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158 | sequence = null; |
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159 | } |
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160 | } |
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161 | if (sequence != null) { |
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162 | sequences.add(sequence); |
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163 | } |
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164 | } |
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165 | } |
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166 | |
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167 | return sequences; |
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168 | } |
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169 | |
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170 | /** |
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171 | * <p> |
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172 | * Finishes a sequence with a random walk. |
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173 | * </p> |
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174 | * |
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175 | * @param sequence |
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176 | * sequence to be finished |
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177 | * @param model |
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178 | * model used for the random walk |
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179 | * @param length |
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180 | * desired length of the sequence |
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181 | * @param validEnd |
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182 | * if the sequence should end in {@link Event#ENDEVENT}. |
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183 | * @return finished sequence of the desired length |
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184 | */ |
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185 | private List<Event> finishSequence(List<Event> sequence, |
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186 | IStochasticProcess model, |
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187 | int length, |
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188 | boolean validEnd) |
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189 | { |
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190 | Random r = new Random(); |
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191 | boolean endFound = false; |
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192 | List<Event> sequenceCopy = new LinkedList<Event>(sequence); |
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193 | final int maxIter = 30000; |
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194 | int iter = 0; |
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195 | while (!endFound && iter < maxIter) { |
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196 | iter++; |
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197 | sequenceCopy = new LinkedList<Event>(sequence); |
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198 | while (!endFound && sequenceCopy.size() <= length) { |
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199 | double randVal = r.nextDouble(); |
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200 | double probSum = 0.0; |
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201 | for (Event symbol : model.getEvents()) { |
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202 | probSum += model.getProbability(sequenceCopy, symbol); |
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203 | if (probSum >= randVal) { |
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204 | if (!(Event.STARTEVENT.equals(symbol) || (!validEnd && Event.ENDEVENT |
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205 | .equals(symbol)))) |
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206 | { |
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207 | // only add the symbol the sequence if it is not |
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208 | // START |
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209 | // or END |
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210 | sequenceCopy.add(symbol); |
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211 | } |
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212 | endFound = |
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213 | Event.ENDEVENT.equals(symbol) || |
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214 | (!validEnd && sequenceCopy.size() == length); |
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215 | break; |
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216 | } |
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217 | } |
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218 | } |
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219 | } |
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220 | if (iter == maxIter) { |
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221 | return null; |
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222 | } |
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223 | return sequenceCopy; |
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224 | } |
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225 | |
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226 | } |
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