135 lines
3.4 KiB
C++
135 lines
3.4 KiB
C++
/***********************************************************************
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* Software License Agreement (BSD License)
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*
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* Copyright 2008-2009 Marius Muja (mariusm@cs.ubc.ca). All rights reserved.
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* Copyright 2008-2009 David G. Lowe (lowe@cs.ubc.ca). All rights reserved.
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*
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* THE BSD LICENSE
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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*
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*************************************************************************/
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#ifndef RANDOM_H
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#define RANDOM_H
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#include <algorithm>
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#include <cstdlib>
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#include <cassert>
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using namespace std;
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namespace cvflann
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{
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/**
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* Seeds the random number generator
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*/
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void seed_random(unsigned int seed);
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/*
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* Generates a random double value.
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*/
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double rand_double(double high = 1.0, double low=0);
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/*
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* Generates a random integer value.
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*/
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int rand_int(int high = RAND_MAX, int low = 0);
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/**
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* Random number generator that returns a distinct number from
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* the [0,n) interval each time.
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*
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* TODO: improve on this to use a generator function instead of an
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* array of randomly permuted numbers
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*/
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class UniqueRandom
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{
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int* vals;
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int size;
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int counter;
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public:
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/**
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* Constructor.
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* Params:
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* n = the size of the interval from which to generate
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* random numbers.
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*/
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UniqueRandom(int n) : vals(NULL) {
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init(n);
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}
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~UniqueRandom()
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{
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delete[] vals;
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}
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/**
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* Initializes the number generator.
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* Params:
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* n = the size of the interval from which to generate
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* random numbers.
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*/
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void init(int n)
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{
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// create and initialize an array of size n
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if (vals == NULL || n!=size) {
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delete[] vals;
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size = n;
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vals = new int[size];
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}
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for(int i=0;i<size;++i) {
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vals[i] = i;
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}
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// shuffle the elements in the array
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// Fisher-Yates shuffle
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for (int i=size;i>0;--i) {
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// int rand = cast(int) (drand48() * n);
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int rnd = rand_int(i);
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assert(rnd >=0 && rnd < i);
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swap(vals[i-1], vals[rnd]);
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}
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counter = 0;
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}
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/**
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* Return a distinct random integer in greater or equal to 0 and less
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* than 'n' on each call. It should be called maximum 'n' times.
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* Returns: a random integer
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*/
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int next() {
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if (counter==size) {
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return -1;
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} else {
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return vals[counter++];
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}
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}
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};
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}
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#endif //RANDOM_H
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