PHP Classes

PHP Permutation and Combination: Compute permutations and combinations of values

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Version License PHP version Categories
permutation-combine 1.0.0Freeware5PHP 5, Statistics
Description 

Author

Anthony Amolochitis

This class compute permutations and combinations of given values.

It can take as parameters a given number of items or a number of items to pick.

The class can compute the total number of possible combinations or permutations of items either allowing repetitions or not.

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  Performance   Level  

Level 3 StarStarStar

 

Example

<?php


class PermutationCombination
{
    /**
     * @var int
     */
    public $nItems = 0 ;
   
    /**
     * @var int
     */
    public $rPicked = 0 ;
       
    /**
     * Compute the N factorial
     * @return int
     */
    protected function Generate_N_Factorial()
    {
        $num = $this->nItems ;
        $factorial = 1 ;
        for( $x = $num ; $x >= 1 ; $x-- )
        {
            $factorial = $factorial * $x ;
        }
        return $factorial ;
    }
   
    /**
     * Compute the R factorial
     * @return int
     */
    protected function Generate_R_Factorial()
    {
        $num = $this->rPicked ;
        $factorial = 1 ;
        for( $x = $num ; $x >= 1 ; $x-- )
        {
            $factorial = $factorial * $x ;
        }
        return $factorial ;
    }
   
    /**
     * Compute the N factorial
     * @return int
     */
    protected function Generate_N_Minus_R_Factorial()
    {
        $num = $this->nItems - $this->rPicked ;
        $factorial = 1 ;
        for( $x = $num ; $x >= 1 ; $x-- )
        {
            $factorial = $factorial * $x ;
        }
        return $factorial ;
    }
   
    /**
     * Compute the (N + R - 1) factorial
     * @return int
     */
    protected function Generate_N_Plus_R_MinusOne_Factorial()
    {
        $num = ( $this->nItems + $this->rPicked - 1 ) ;
        $factorial = 1 ;
        for( $x = $num ; $x >= 1 ; $x-- )
        {
            $factorial = $factorial * $x ;
        }
        return $factorial ;
    }
   
    /**
     * Compute the (N + R - 1) factorial
     * @return int
     */
    protected function Generate_N_Minus_One_Factorial()
    {
        $num = ( $this->nItems - 1 ) ;
        $factorial = 1 ;
        for( $x = $num ; $x >= 1 ; $x-- )
        {
            $factorial = $factorial * $x ;
        }
        return $factorial ;
    }
   
    /**
     * nPr
     * Ordering matters.
     * a and b are different that b and a.
     * @return float
     */
    public function ComputePermutations()
    {
        $nFactorial = $this->Generate_N_Factorial();
        $n_Minus_r_Factorial = $this->Generate_N_Minus_R_Factorial() ;
       
        return ( $nFactorial / $n_Minus_r_Factorial );
    }
   
    /**
     * Ordering does not matter
     * a and b are different that b and a.
     * @return float
     */
    public function ComputePermutations_AllowRepitition()
    {
        return pow($this->nItems, $this->rPicked);
    }
   
    /**
     * nCr
     * Order does not matter.
     * a and b is the same as b and a
     * @return float
     */
    public function ComputeCombinations()
    {
        $nFactorial = $this->Generate_N_Factorial();
        $rFactorial = $this->Generate_R_Factorial() ;
        $n_Minus_r_Factorial = $this->Generate_N_Minus_R_Factorial() ;
       
        return ( $nFactorial / ($n_Minus_r_Factorial * $rFactorial) );
    }
   
   
    public function ComputeCombination_RepititionAllowed()
    {
        $numerator = $this->Generate_N_Plus_R_MinusOne_Factorial();
        $rFactorial = $this->Generate_R_Factorial() ;
        $nMinusOneFactorial = $this->Generate_N_Minus_One_Factorial();
       
        return ( $numerator / ($rFactorial * $nMinusOneFactorial) );
    }
   
}


$t = new PermutationCombination();
$t->nItems = 5 ;
$t->rPicked = 5 ;

echo 'Permutations: ' ;
echo $t->ComputePermutations() ;

echo '<br/>';
echo 'Permutations Allow Repitition: ' ;
echo $t->ComputePermutations_AllowRepitition() ;


echo '<br/>';
echo 'Combinations: ' ;
echo $t->ComputeCombinations() ;

echo '<br/>';
echo 'Combinations with Repitition: ' ;
echo $t->ComputeCombination_RepititionAllowed() ;


?>

  Files folder image Files (2)  
File Role Description
Plain text file ExampleUsage.php Example Example Usage of the class
Plain text file PermutationCombination.php Class Compute Combinations and Permutations

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