Raymond | dee0849 | 2015-04-02 10:43:13 -0700 | [diff] [blame] | 1 | /* |
| 2 | * Licensed to the Apache Software Foundation (ASF) under one or more |
| 3 | * contributor license agreements. See the NOTICE file distributed with |
| 4 | * this work for additional information regarding copyright ownership. |
| 5 | * The ASF licenses this file to You under the Apache License, Version 2.0 |
| 6 | * (the "License"); you may not use this file except in compliance with |
| 7 | * the License. You may obtain a copy of the License at |
| 8 | * |
| 9 | * http://www.apache.org/licenses/LICENSE-2.0 |
| 10 | * |
| 11 | * Unless required by applicable law or agreed to in writing, software |
| 12 | * distributed under the License is distributed on an "AS IS" BASIS, |
| 13 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 14 | * See the License for the specific language governing permissions and |
| 15 | * limitations under the License. |
| 16 | */ |
| 17 | |
| 18 | package org.apache.commons.math.random; |
| 19 | import java.io.BufferedReader; |
| 20 | import java.io.IOException; |
| 21 | import java.io.InputStreamReader; |
| 22 | import java.net.MalformedURLException; |
| 23 | import java.net.URL; |
| 24 | |
| 25 | import org.apache.commons.math.MathRuntimeException; |
| 26 | import org.apache.commons.math.exception.util.LocalizedFormats; |
| 27 | |
| 28 | /** |
| 29 | * Generates values for use in simulation applications. |
| 30 | * <p> |
| 31 | * How values are generated is determined by the <code>mode</code> |
| 32 | * property.</p> |
| 33 | * <p> |
| 34 | * Supported <code>mode</code> values are: <ul> |
| 35 | * <li> DIGEST_MODE -- uses an empirical distribution </li> |
| 36 | * <li> REPLAY_MODE -- replays data from <code>valuesFileURL</code></li> |
| 37 | * <li> UNIFORM_MODE -- generates uniformly distributed random values with |
| 38 | * mean = <code>mu</code> </li> |
| 39 | * <li> EXPONENTIAL_MODE -- generates exponentially distributed random values |
| 40 | * with mean = <code>mu</code></li> |
| 41 | * <li> GAUSSIAN_MODE -- generates Gaussian distributed random values with |
| 42 | * mean = <code>mu</code> and |
| 43 | * standard deviation = <code>sigma</code></li> |
| 44 | * <li> CONSTANT_MODE -- returns <code>mu</code> every time.</li></ul></p> |
| 45 | * |
| 46 | * @version $Revision: 1003886 $ $Date: 2010-10-02 23:04:44 +0200 (sam. 02 oct. 2010) $ |
| 47 | * |
| 48 | */ |
| 49 | public class ValueServer { |
| 50 | |
| 51 | /** Use empirical distribution. */ |
| 52 | public static final int DIGEST_MODE = 0; |
| 53 | |
| 54 | /** Replay data from valuesFilePath. */ |
| 55 | public static final int REPLAY_MODE = 1; |
| 56 | |
| 57 | /** Uniform random deviates with mean = μ. */ |
| 58 | public static final int UNIFORM_MODE = 2; |
| 59 | |
| 60 | /** Exponential random deviates with mean = μ. */ |
| 61 | public static final int EXPONENTIAL_MODE = 3; |
| 62 | |
| 63 | /** Gaussian random deviates with mean = μ, std dev = σ. */ |
| 64 | public static final int GAUSSIAN_MODE = 4; |
| 65 | |
| 66 | /** Always return mu */ |
| 67 | public static final int CONSTANT_MODE = 5; |
| 68 | |
| 69 | /** mode determines how values are generated. */ |
| 70 | private int mode = 5; |
| 71 | |
| 72 | /** URI to raw data values. */ |
| 73 | private URL valuesFileURL = null; |
| 74 | |
| 75 | /** Mean for use with non-data-driven modes. */ |
| 76 | private double mu = 0.0; |
| 77 | |
| 78 | /** Standard deviation for use with GAUSSIAN_MODE. */ |
| 79 | private double sigma = 0.0; |
| 80 | |
| 81 | /** Empirical probability distribution for use with DIGEST_MODE. */ |
| 82 | private EmpiricalDistribution empiricalDistribution = null; |
| 83 | |
| 84 | /** File pointer for REPLAY_MODE. */ |
| 85 | private BufferedReader filePointer = null; |
| 86 | |
| 87 | /** RandomDataImpl to use for random data generation. */ |
| 88 | private final RandomData randomData; |
| 89 | |
| 90 | // Data generation modes ====================================== |
| 91 | |
| 92 | /** Creates new ValueServer */ |
| 93 | public ValueServer() { |
| 94 | randomData = new RandomDataImpl(); |
| 95 | } |
| 96 | |
| 97 | /** |
| 98 | * Construct a ValueServer instance using a RandomData as its source |
| 99 | * of random data. |
| 100 | * |
| 101 | * @param randomData the RandomData instance used to source random data |
| 102 | * @since 1.1 |
| 103 | */ |
| 104 | public ValueServer(RandomData randomData) { |
| 105 | this.randomData = randomData; |
| 106 | } |
| 107 | |
| 108 | /** |
| 109 | * Returns the next generated value, generated according |
| 110 | * to the mode value (see MODE constants). |
| 111 | * |
| 112 | * @return generated value |
| 113 | * @throws IOException in REPLAY_MODE if a file I/O error occurs |
| 114 | */ |
| 115 | public double getNext() throws IOException { |
| 116 | switch (mode) { |
| 117 | case DIGEST_MODE: return getNextDigest(); |
| 118 | case REPLAY_MODE: return getNextReplay(); |
| 119 | case UNIFORM_MODE: return getNextUniform(); |
| 120 | case EXPONENTIAL_MODE: return getNextExponential(); |
| 121 | case GAUSSIAN_MODE: return getNextGaussian(); |
| 122 | case CONSTANT_MODE: return mu; |
| 123 | default: throw MathRuntimeException.createIllegalStateException( |
| 124 | LocalizedFormats.UNKNOWN_MODE, |
| 125 | mode, |
| 126 | "DIGEST_MODE", DIGEST_MODE, "REPLAY_MODE", REPLAY_MODE, |
| 127 | "UNIFORM_MODE", UNIFORM_MODE, "EXPONENTIAL_MODE", EXPONENTIAL_MODE, |
| 128 | "GAUSSIAN_MODE", GAUSSIAN_MODE, "CONSTANT_MODE", CONSTANT_MODE); |
| 129 | } |
| 130 | } |
| 131 | |
| 132 | /** |
| 133 | * Fills the input array with values generated using getNext() repeatedly. |
| 134 | * |
| 135 | * @param values array to be filled |
| 136 | * @throws IOException in REPLAY_MODE if a file I/O error occurs |
| 137 | */ |
| 138 | public void fill(double[] values) throws IOException { |
| 139 | for (int i = 0; i < values.length; i++) { |
| 140 | values[i] = getNext(); |
| 141 | } |
| 142 | } |
| 143 | |
| 144 | /** |
| 145 | * Returns an array of length <code>length</code> with values generated |
| 146 | * using getNext() repeatedly. |
| 147 | * |
| 148 | * @param length length of output array |
| 149 | * @return array of generated values |
| 150 | * @throws IOException in REPLAY_MODE if a file I/O error occurs |
| 151 | */ |
| 152 | public double[] fill(int length) throws IOException { |
| 153 | double[] out = new double[length]; |
| 154 | for (int i = 0; i < length; i++) { |
| 155 | out[i] = getNext(); |
| 156 | } |
| 157 | return out; |
| 158 | } |
| 159 | |
| 160 | /** |
| 161 | * Computes the empirical distribution using values from the file |
| 162 | * in <code>valuesFileURL</code>, using the default number of bins. |
| 163 | * <p> |
| 164 | * <code>valuesFileURL</code> must exist and be |
| 165 | * readable by *this at runtime.</p> |
| 166 | * <p> |
| 167 | * This method must be called before using <code>getNext()</code> |
| 168 | * with <code>mode = DIGEST_MODE</code></p> |
| 169 | * |
| 170 | * @throws IOException if an I/O error occurs reading the input file |
| 171 | */ |
| 172 | public void computeDistribution() throws IOException { |
| 173 | empiricalDistribution = new EmpiricalDistributionImpl(); |
| 174 | empiricalDistribution.load(valuesFileURL); |
| 175 | } |
| 176 | |
| 177 | /** |
| 178 | * Computes the empirical distribution using values from the file |
| 179 | * in <code>valuesFileURL</code> and <code>binCount</code> bins. |
| 180 | * <p> |
| 181 | * <code>valuesFileURL</code> must exist and be readable by this process |
| 182 | * at runtime.</p> |
| 183 | * <p> |
| 184 | * This method must be called before using <code>getNext()</code> |
| 185 | * with <code>mode = DIGEST_MODE</code></p> |
| 186 | * |
| 187 | * @param binCount the number of bins used in computing the empirical |
| 188 | * distribution |
| 189 | * @throws IOException if an error occurs reading the input file |
| 190 | */ |
| 191 | public void computeDistribution(int binCount) |
| 192 | throws IOException { |
| 193 | empiricalDistribution = new EmpiricalDistributionImpl(binCount); |
| 194 | empiricalDistribution.load(valuesFileURL); |
| 195 | mu = empiricalDistribution.getSampleStats().getMean(); |
| 196 | sigma = empiricalDistribution.getSampleStats().getStandardDeviation(); |
| 197 | } |
| 198 | |
| 199 | /** Getter for property mode. |
| 200 | * @return Value of property mode. |
| 201 | */ |
| 202 | public int getMode() { |
| 203 | return mode; |
| 204 | } |
| 205 | |
| 206 | /** Setter for property mode. |
| 207 | * @param mode New value of property mode. |
| 208 | */ |
| 209 | public void setMode(int mode) { |
| 210 | this.mode = mode; |
| 211 | } |
| 212 | |
| 213 | /** |
| 214 | * Getter for <code>valuesFileURL<code> |
| 215 | * @return Value of property valuesFileURL. |
| 216 | */ |
| 217 | public URL getValuesFileURL() { |
| 218 | return valuesFileURL; |
| 219 | } |
| 220 | |
| 221 | /** |
| 222 | * Sets the <code>valuesFileURL</code> using a string URL representation |
| 223 | * @param url String representation for new valuesFileURL. |
| 224 | * @throws MalformedURLException if url is not well formed |
| 225 | */ |
| 226 | public void setValuesFileURL(String url) throws MalformedURLException { |
| 227 | this.valuesFileURL = new URL(url); |
| 228 | } |
| 229 | |
| 230 | /** |
| 231 | * Sets the <code>valuesFileURL</code> |
| 232 | * @param url New value of property valuesFileURL. |
| 233 | */ |
| 234 | public void setValuesFileURL(URL url) { |
| 235 | this.valuesFileURL = url; |
| 236 | } |
| 237 | |
| 238 | /** Getter for property empiricalDistribution. |
| 239 | * @return Value of property empiricalDistribution. |
| 240 | */ |
| 241 | public EmpiricalDistribution getEmpiricalDistribution() { |
| 242 | return empiricalDistribution; |
| 243 | } |
| 244 | |
| 245 | /** |
| 246 | * Resets REPLAY_MODE file pointer to the beginning of the <code>valuesFileURL</code>. |
| 247 | * |
| 248 | * @throws IOException if an error occurs opening the file |
| 249 | */ |
| 250 | public void resetReplayFile() throws IOException { |
| 251 | if (filePointer != null) { |
| 252 | try { |
| 253 | filePointer.close(); |
| 254 | filePointer = null; |
| 255 | } catch (IOException ex) { |
| 256 | // ignore |
| 257 | } |
| 258 | } |
| 259 | filePointer = new BufferedReader(new InputStreamReader(valuesFileURL.openStream())); |
| 260 | } |
| 261 | |
| 262 | /** |
| 263 | * Closes <code>valuesFileURL</code> after use in REPLAY_MODE. |
| 264 | * |
| 265 | * @throws IOException if an error occurs closing the file |
| 266 | */ |
| 267 | public void closeReplayFile() throws IOException { |
| 268 | if (filePointer != null) { |
| 269 | filePointer.close(); |
| 270 | filePointer = null; |
| 271 | } |
| 272 | } |
| 273 | |
| 274 | /** Getter for property mu. |
| 275 | * @return Value of property mu. |
| 276 | */ |
| 277 | public double getMu() { |
| 278 | return mu; |
| 279 | } |
| 280 | |
| 281 | /** Setter for property mu. |
| 282 | * @param mu New value of property mu. |
| 283 | */ |
| 284 | public void setMu(double mu) { |
| 285 | this.mu = mu; |
| 286 | } |
| 287 | |
| 288 | /** Getter for property sigma. |
| 289 | * @return Value of property sigma. |
| 290 | */ |
| 291 | public double getSigma() { |
| 292 | return sigma; |
| 293 | } |
| 294 | |
| 295 | /** Setter for property sigma. |
| 296 | * @param sigma New value of property sigma. |
| 297 | */ |
| 298 | public void setSigma(double sigma) { |
| 299 | this.sigma = sigma; |
| 300 | } |
| 301 | |
| 302 | //------------- private methods --------------------------------- |
| 303 | |
| 304 | /** |
| 305 | * Gets a random value in DIGEST_MODE. |
| 306 | * <p> |
| 307 | * <strong>Preconditions</strong>: <ul> |
| 308 | * <li>Before this method is called, <code>computeDistribution()</code> |
| 309 | * must have completed successfully; otherwise an |
| 310 | * <code>IllegalStateException</code> will be thrown</li></ul></p> |
| 311 | * |
| 312 | * @return next random value from the empirical distribution digest |
| 313 | */ |
| 314 | private double getNextDigest() { |
| 315 | if ((empiricalDistribution == null) || |
| 316 | (empiricalDistribution.getBinStats().size() == 0)) { |
| 317 | throw MathRuntimeException.createIllegalStateException(LocalizedFormats.DIGEST_NOT_INITIALIZED); |
| 318 | } |
| 319 | return empiricalDistribution.getNextValue(); |
| 320 | } |
| 321 | |
| 322 | /** |
| 323 | * Gets next sequential value from the <code>valuesFileURL</code>. |
| 324 | * <p> |
| 325 | * Throws an IOException if the read fails.</p> |
| 326 | * <p> |
| 327 | * This method will open the <code>valuesFileURL</code> if there is no |
| 328 | * replay file open.</p> |
| 329 | * <p> |
| 330 | * The <code>valuesFileURL</code> will be closed and reopened to wrap around |
| 331 | * from EOF to BOF if EOF is encountered. EOFException (which is a kind of |
| 332 | * IOException) may still be thrown if the <code>valuesFileURL</code> is |
| 333 | * empty.</p> |
| 334 | * |
| 335 | * @return next value from the replay file |
| 336 | * @throws IOException if there is a problem reading from the file |
| 337 | * @throws NumberFormatException if an invalid numeric string is |
| 338 | * encountered in the file |
| 339 | */ |
| 340 | private double getNextReplay() throws IOException { |
| 341 | String str = null; |
| 342 | if (filePointer == null) { |
| 343 | resetReplayFile(); |
| 344 | } |
| 345 | if ((str = filePointer.readLine()) == null) { |
| 346 | // we have probably reached end of file, wrap around from EOF to BOF |
| 347 | closeReplayFile(); |
| 348 | resetReplayFile(); |
| 349 | if ((str = filePointer.readLine()) == null) { |
| 350 | throw MathRuntimeException.createEOFException(LocalizedFormats.URL_CONTAINS_NO_DATA, |
| 351 | valuesFileURL); |
| 352 | } |
| 353 | } |
| 354 | return Double.valueOf(str).doubleValue(); |
| 355 | } |
| 356 | |
| 357 | /** |
| 358 | * Gets a uniformly distributed random value with mean = mu. |
| 359 | * |
| 360 | * @return random uniform value |
| 361 | */ |
| 362 | private double getNextUniform() { |
| 363 | return randomData.nextUniform(0, 2 * mu); |
| 364 | } |
| 365 | |
| 366 | /** |
| 367 | * Gets an exponentially distributed random value with mean = mu. |
| 368 | * |
| 369 | * @return random exponential value |
| 370 | */ |
| 371 | private double getNextExponential() { |
| 372 | return randomData.nextExponential(mu); |
| 373 | } |
| 374 | |
| 375 | /** |
| 376 | * Gets a Gaussian distributed random value with mean = mu |
| 377 | * and standard deviation = sigma. |
| 378 | * |
| 379 | * @return random Gaussian value |
| 380 | */ |
| 381 | private double getNextGaussian() { |
| 382 | return randomData.nextGaussian(mu, sigma); |
| 383 | } |
| 384 | |
| 385 | } |