Permutator¶

createInstance¶

static Permutator *createInstance(uint iInitSize);

Create a Permutator instance with specified buffer size.

iInitSize

Initial size of buffer.

Returns a pointer to the instance.

destructor¶

~Permutator();

The destructor frees the memory allocated for the buffer.

permute¶

const uint *permute(uint iNumTot, uint iNumSel, WELL512 *pWELL);
const uint *permute(uint iNumTot, uint iNumSel);

Replaces the first iNumSel elements of its internal buffer with random elements from [1,iNumTot-1]. If iNumTot == iNumSel this will yield a permutation of [0, iNumTot-1]. The version without a WELL512* argument calls the standard rand() function (be sure to initialize it with srand() before using it).

This function will reallocate the buffer if iNumTot is greater than the current size of the buffer.

iNumTot

Total number of elements.

iNumSel

Number of elements to select.

pWELL

A WELL512 random number generator.

Returns a pointer to the internal buffer.

permuteBuf¶

template<typename T>;
T *permuteBuf(uint iNumTot, uint iNumSel, WELL512 *pWELL, T *pBuf);

template<typename T>
T *permuteBuf(uint iNumTot, uint iNumSel, T *pBuf);

Replaces the first iNumSel elements of pBuf with random elements from pBuf. If iNumTot == iNumSel this will yield a permutation of the elements pBuf. The version without a WELL512* argument calls the standard rand() function (be sure to initialize it with srand() before using it).

iNumTot

Total number of elements in buffer.

iNumSel

Number of elements to select.

pWELL

A WELL512 random number generator.

getSize¶

uint getSize();

Returns size of buffer.

getPrevTot¶

uint getPrevTot();

Returns previous size of buffer.

getPerm¶

const uint* getPerm():

Return a pointer to the internal buffer.

setSize¶

void setSize(uint iSize);

Set size of buffer.

constructor¶

Permutator(uint iInitSize);

init¶

int init();

resize¶

void resize(uint iNewSize);

g++ perm_example.cpp Permutator.cpp WELL512.cpp -std=c++20 -o perm_example

#include <cstdio>
#include <cstdlib>
#include <utility>

#include "WELL512.h"
#include "Permutator.h"


int main(int iArgC, char *apArgV[]) {

    int iResult = 0;


    // WELL512 seeded with current time
    WELL512 *pWELL = new WELL512();

    std::pair<int, std::string> apairs[] ={{0,"zero"},  {1,"one"},  {2,"two"},
                                           {3,"three"}, {4,"four"}, {5,"five"},{6,"six"}};

    Permutator *pPerm = Permutator::createInstance(5);

    // select 3 random elements from [0,4]
    unsigned int *pRes1 = pPerm->permute(5, 3, pWELL);
    for (unsigned i = 0; i < 3; i++) {
        printf(" %d", pRes1[i]);
    }
    printf("\n");

    // get a random permutation of [0,9]
    unsigned int *pRes2 = pPerm->permute(9, 9, pWELL);
    for (unsigned i = 0; i < 9; i++) {
        printf(" %d", pRes2[i]);
    }
    printf("\n");

    // select 4 random elements from the array apairs
    std::pair<int, std::string> *pRes3 = pPerm->permuteBuf(7, 4, pWELL, apairs);
    for (unsigned i = 0; i < 4; i++) {
        printf(" %d:%s", pRes3[i].first, pRes3[i].second.c_str());
    }
    printf("\n");

    delete pPerm;
    delete pWELL;
    return iResult;
}