1 files changed, 132 insertions, 0 deletions
diff --git a/src/de/lmu/ifi/dbs/elki/math/statistics/distribution/UniformDistribution.java b/src/de/lmu/ifi/dbs/elki/math/statistics/distribution/UniformDistribution.java
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+++ b/src/de/lmu/ifi/dbs/elki/math/statistics/distribution/UniformDistribution.java
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+package de.lmu.ifi.dbs.elki.math.statistics.distribution;
+
+/*
+ This file is part of ELKI:
+ Environment for Developing KDD-Applications Supported by Index-Structures
+
+ Copyright (C) 2012
+ Ludwig-Maximilians-Universität München
+ Lehr- und Forschungseinheit für Datenbanksysteme
+ ELKI Development Team
+
+ This program is free software: you can redistribute it and/or modify
+ it under the terms of the GNU Affero General Public License as published by
+ the Free Software Foundation, either version 3 of the License, or
+ (at your option) any later version.
+
+ This program is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ GNU Affero General Public License for more details.
+
+ You should have received a copy of the GNU Affero General Public License
+ along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+import java.util.Random;
+
+/**
+ * Uniform distribution.
+ * 
+ * @author Erich Schubert
+ */
+public class UniformDistribution implements Distribution {
+  /**
+   * Minimum
+   */
+  private double min;
+
+  /**
+   * Maximum
+   */
+  private double max;
+
+  /**
+   * Len := max - min
+   */
+  private double len;
+
+  /**
+   * The random generator.
+   */
+  private Random random;
+
+  /**
+   * Constructor for a uniform distribution on the interval [min, max[
+   * 
+   * @param min Minimum value
+   * @param max Maximum value
+   * @param random Random generator
+   */
+  public UniformDistribution(double min, double max, Random random) {
+    super();
+    // Swap parameters if they were given incorrectly.
+    if(min > max) {
+      double tmp = min;
+      min = max;
+      max = tmp;
+    }
+    this.min = min;
+    this.max = max;
+    this.len = max - min;
+    this.random = random;
+  }
+
+  /**
+   * Constructor for a uniform distribution on the interval [min, max[
+   * 
+   * @param min Minimum value
+   * @param max Maximum value
+   */
+  public UniformDistribution(double min, double max) {
+    this(min, max, new Random());
+  }
+
+  @Override
+  public double pdf(double val) {
+    if(val < min || val >= max) {
+      return 0.0;
+    }
+    return 1.0 / len;
+  }
+
+  @Override
+  public double cdf(double val) {
+    if(val < min) {
+      return 0.0;
+    }
+    if(val > max) {
+      return 1.0;
+    }
+    return (val - min) / len;
+  }
+
+  @Override
+  public double nextRandom() {
+    return min + random.nextDouble() * len;
+  }
+
+  /**
+   * Simple toString explaining the distribution parameters.
+   * 
+   * Used in describing cluster models.
+   */
+  @Override
+  public String toString() {
+    return "Uniform Distribution (min=" + min + ", max=" + max + ")";
+  }
+
+  /**
+   * @return the minimum value
+   */
+  public double getMin() {
+    return min;
+  }
+
+  /**
+   * @return the maximum value
+   */
+  public double getMax() {
+    return max;
+  }
+}
+\ No newline at end of file