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The SplHeap class

(PHP 5 >= 5.3.0)

Introduction

The SplHeap class provides the main functionalities of a Heap.

Class synopsis

abstract SplHeap implements Iterator , Countable {
/* Methods */
public __construct ( void )
abstract protected int compare ( mixed $value1 , mixed $value2 )
public int count ( void )
public mixed current ( void )
public mixed extract ( void )
public void insert ( mixed $value )
public bool isEmpty ( void )
public mixed key ( void )
public void next ( void )
public void recoverFromCorruption ( void )
public void rewind ( void )
public mixed top ( void )
public bool valid ( void )
}

Table of Contents

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User Contributed Notes 2 notes

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20
Michelangelo van Dam
4 years ago
To have a good idea what you can do with SplHeap, I created a little example script that will show the rankings of Belgian soccer teams in the Jupiler League.

<?php
/**
* A class that extends SplHeap for showing rankings in the Belgian
* soccer tournament JupilerLeague
*/
class JupilerLeague extends SplHeap
{
   
/**
     * We modify the abstract method compare so we can sort our
     * rankings using the values of a given array
     */
   
public function compare($array1, $array2)
    {
       
$values1 = array_values($array1);
       
$values2 = array_values($array2);
        if (
$values1[0] === $values2[0]) return 0;
        return
$values1[0] < $values2[0] ? -1 : 1;
    }
}

// Let's populate our heap here (data of 2009)
$heap = new JupilerLeague();
$heap->insert(array ('AA Gent' => 15));
$heap->insert(array ('Anderlecht' => 20));
$heap->insert(array ('Cercle Brugge' => 11));
$heap->insert(array ('Charleroi' => 12));
$heap->insert(array ('Club Brugge' => 21));
$heap->insert(array ('G. Beerschot' => 15));
$heap->insert(array ('Kortrijk' => 10));
$heap->insert(array ('KV Mechelen' => 18));
$heap->insert(array ('Lokeren' => 10));
$heap->insert(array ('Moeskroen' => 7));
$heap->insert(array ('Racing Genk' => 11));
$heap->insert(array ('Roeselare' => 6));
$heap->insert(array ('Standard' => 20));
$heap->insert(array ('STVV' => 17));
$heap->insert(array ('Westerlo' => 10));
$heap->insert(array ('Zulte Waregem' => 15));

// For displaying the ranking we move up to the first node
$heap->top();

// Then we iterate through each node for displaying the result
while ($heap->valid()) {
  list (
$team, $score) = each ($heap->current());
  echo
$team . ': ' . $score . PHP_EOL;
 
$heap->next();
}
?>

This results in the following output:
Club Brugge: 21
Anderlecht: 20
Standard: 20
KV Mechelen: 18
STVV: 17
Zulte Waregem: 15
AA Gent: 15
G. Beerschot: 15
Charleroi: 12
Racing Genk: 11
Cercle Brugge: 11
Kortrijk: 10
Lokeren: 10
Westerlo: 10
Moeskroen: 7
Roeselare: 6

Hope this example paved the way for more complex implementations of SplHeap.
up
1
igorsantos07 at gmail dot com
2 months ago
While Michelangelo Van Dam example (http://br2.php.net/manual/en/class.splheap.php#93930) is a great demonstration of what can be done with SplHeap, this implementation is exactly what SplPriorityQueue does - based on SplMaxHeap. If you're planning to copy that snippet, go no further! There's a SPL class that does exactly what you want :)
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