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* Software License Agreement (BSD License)
*
* Copyright 2008-2009 Marius Muja (mariusm@cs.ubc.ca). All rights reserved.
* Copyright 2008-2009 David G. Lowe (lowe@cs.ubc.ca). All rights reserved.
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#ifndef OPENCV_FLANN_RANDOM_H
#define OPENCV_FLANN_RANDOM_H
#include <algorithm>
#include <cstdlib>
#include <vector>
#include "general.h"
namespace cvflann
{
/**
* Seeds the random number generator
* @param seed Random seed
*/
inline void seed_random(unsigned int seed)
{
srand(seed);
}
/*
* Generates a random double value.
*/
/**
* Generates a random double value.
* @param high Upper limit
* @param low Lower limit
* @return Random double value
*/
inline double rand_double(double high = 1.0, double low = 0)
{
return low + ((high-low) * (std::rand() / (RAND_MAX + 1.0)));
}
/**
* Generates a random integer value.
* @param high Upper limit
* @param low Lower limit
* @return Random integer value
*/
inline int rand_int(int high = RAND_MAX, int low = 0)
{
return low + (int) ( double(high-low) * (std::rand() / (RAND_MAX + 1.0)));
}
/**
* Random number generator that returns a distinct number from
* the [0,n) interval each time.
*/
class UniqueRandom
{
std::vector<int> vals_;
int size_;
int counter_;
public:
/**
* Constructor.
* @param n Size of the interval from which to generate
* @return
*/
UniqueRandom(int n)
{
init(n);
}
/**
* Initializes the number generator.
* @param n the size of the interval from which to generate random numbers.
*/
void init(int n)
{
// create and initialize an array of size n
vals_.resize(n);
size_ = n;
for (int i = 0; i < size_; ++i) vals_[i] = i;
// shuffle the elements in the array
std::random_shuffle(vals_.begin(), vals_.end());
counter_ = 0;
}
/**
* Return a distinct random integer in greater or equal to 0 and less
* than 'n' on each call. It should be called maximum 'n' times.
* Returns: a random integer
*/
int next()
{
if (counter_ == size_) {
return -1;
}
else {
return vals_[counter_++];
}
}
};
}
#endif //OPENCV_FLANN_RANDOM_H