permutation.cpp

Scalable k-means software and test datasets This package (a Unix tar file, gzipped) contains the sou

/* Scalable K-means clustering software
Copyright (C) 2000  Fredrik Farnstrom and James Lewis

This program is free software; you can redistribute it and/or
modify it under the terms of the GNU General Public License
as published by the Free Software Foundation; either version 2
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 General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.


See the file README.TXT for more information.

*/

/* permutation.cpp */

#include <stdio.h>
#include "common.h"
#include "permutation.h"
#include "random.h"


// Create a new permutation, returning integers 1..num. The permutation
// can be used immediately, reset() does not have to be called first.

Permutation::Permutation(int num) : maxNumNumbers(num)
{
	numbers = new int[maxNumNumbers];
	randomGenerator = RandomGenerator::getDefaultRandomGenerator();
	reset();
}

Permutation::Permutation(int num, RandomGenerator *randgen) :
		maxNumNumbers(num), randomGenerator(randgen)
{
	numbers = new int[maxNumNumbers];
	reset();
}


// Destructor.

Permutation::~Permutation()
{
	if(numbers)
		delete []numbers;
}


// Reset permutation, i.e the next maxNumNumbers calls to
// getNumber will return integers 1..maxNumNumbers in random order.

void Permutation::reset(void)
{
	int i, *p = numbers;
	for(i = 0; i < maxNumNumbers; i++)
		*p++ = i;
	currentNumNumbers = maxNumNumbers;
}


// Reset permutation and set number of numbers in the permutation.

void Permutation::reset(int num)
{
	if(numbers)
		delete []numbers;
	maxNumNumbers = num;
	numbers = new int[maxNumNumbers];
	reset();
}


// Return next number from the permutation. After maxNumNumbers calls
// to getNumber(), reset() will be called automatically, and a new
// sequence of random number will be created.

int Permutation::getNumber(void)
{
//	int n = (rand() >> 3) % currentNumNumbers, num;
//	int n = (randomGenerator->randomInt() >> 3) % currentNumNumbers, num;
//1+(int) (10.0*rand()/(RAND_MAX+1.0))

//	printf("getNumber(): %d %d %d\n", maxNumNumbers, currentNumNumbers, this);


	unsigned long n = (unsigned long)((REAL)currentNumNumbers*
			randomGenerator->randomInt()/
			(randomGenerator->maxRandomInt() + 1.0));

	int num = numbers[n];
	if(n < currentNumNumbers - 1)
		numbers[n] = numbers[currentNumNumbers - 1];
	if(!--currentNumNumbers)
		reset();
	return num;
}


/* End of file permutation.cpp */