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Thirdparty/DBoW2/DUtils/Random.h

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+/*	
+ * File: Random.h
+ * Project: DUtils library
+ * Author: Dorian Galvez-Lopez
+ * Date: April 2010, November 2011
+ * Description: manages pseudo-random numbers
+ * License: see the LICENSE.txt file
+ *
+ */
+
+#pragma once
+#ifndef __D_RANDOM__
+#define __D_RANDOM__
+
+#include <cstdlib>
+#include <vector>
+
+namespace DUtils {
+
+/// Functions to generate pseudo-random numbers
+class Random
+{
+public:
+  class UnrepeatedRandomizer;
+  
+public:
+	/**
+	 * Sets the random number seed to the current time
+	 */
+	static void SeedRand();
+	
+	/**
+	 * Sets the random number seed to the current time only the first
+	 * time this function is called
+	 */
+	static void SeedRandOnce();
+
+	/** 
+	 * Sets the given random number seed
+	 * @param seed
+	 */
+	static void SeedRand(int seed);
+
+	/** 
+	 * Sets the given random number seed only the first time this function 
+	 * is called
+	 * @param seed
+	 */
+	static void SeedRandOnce(int seed);
+
+	/**
+	 * Returns a random number in the range [0..1]
+	 * @return random T number in [0..1]
+	 */
+	template <class T>
+	static T RandomValue(){
+		return (T)rand()/(T)RAND_MAX;
+	}
+
+	/**
+	 * Returns a random number in the range [min..max]
+	 * @param min
+	 * @param max
+	 * @return random T number in [min..max]
+	 */
+	template <class T>
+	static T RandomValue(T min, T max){
+		return Random::RandomValue<T>() * (max - min) + min;
+	}
+
+	/**
+	 * Returns a random int in the range [min..max]
+	 * @param min
+	 * @param max
+	 * @return random int in [min..max]
+	 */
+	static int RandomInt(int min, int max);
+	
+	/** 
+	 * Returns a random number from a gaussian distribution
+	 * @param mean
+	 * @param sigma standard deviation
+	 */
+	template <class T>
+	static T RandomGaussianValue(T mean, T sigma)
+	{
+    // Box-Muller transformation
+    T x1, x2, w, y1;
+
+    do {
+      x1 = (T)2. * RandomValue<T>() - (T)1.;
+      x2 = (T)2. * RandomValue<T>() - (T)1.;
+      w = x1 * x1 + x2 * x2;
+    } while ( w >= (T)1. || w == (T)0. );
+
+    w = sqrt( ((T)-2.0 * log( w ) ) / w );
+    y1 = x1 * w;
+
+    return( mean + y1 * sigma );
+	}
+
+private:
+
+  /// If SeedRandOnce() or SeedRandOnce(int) have already been called
+  static bool m_already_seeded;
+  
+};
+
+// ---------------------------------------------------------------------------
+
+/// Provides pseudo-random numbers with no repetitions
+class Random::UnrepeatedRandomizer
+{
+public:
+
+  /** 
+   * Creates a randomizer that returns numbers in the range [min, max]
+   * @param min
+   * @param max
+   */
+  UnrepeatedRandomizer(int min, int max);
+  ~UnrepeatedRandomizer(){}
+  
+  /**
+   * Copies a randomizer
+   * @param rnd
+   */
+  UnrepeatedRandomizer(const UnrepeatedRandomizer& rnd);
+  
+  /**
+   * Copies a randomizer
+   * @param rnd
+   */
+  UnrepeatedRandomizer& operator=(const UnrepeatedRandomizer& rnd);
+  
+  /** 
+   * Returns a random number not given before. If all the possible values
+   * were already given, the process starts again
+   * @return unrepeated random number
+   */
+  int get();
+  
+  /**
+   * Returns whether all the possible values between min and max were
+   * already given. If get() is called when empty() is true, the behaviour
+   * is the same than after creating the randomizer
+   * @return true iff all the values were returned
+   */
+  inline bool empty() const { return m_values.empty(); }
+  
+  /**
+   * Returns the number of values still to be returned
+   * @return amount of values to return
+   */
+  inline unsigned int left() const { return m_values.size(); }
+  
+  /**
+   * Resets the randomizer as it were just created
+   */
+  void reset();
+  
+protected:
+
+  /** 
+   * Creates the vector with available values
+   */
+  void createValues();
+
+protected:
+
+  /// Min of range of values
+  int m_min;
+  /// Max of range of values
+  int m_max;
+
+  /// Available values
+  std::vector<int> m_values;
+
+};
+
+}
+
+#endif
+