Shortest path in a map

<?php
class KruskalsAlgorithm
{
	public function shortest_path( $path_list )
	{
		$points = array();
		$shortest_path = array();
		foreach ( $this->sort_2d( $path_list , 2 ) as $path )
		{
			if ( !in_array( $path[ 0 ] , $points ) || !in_array( $path[ 1 ] , $points ) )
			{
				$shortest_path[] = $path;
				if ( !in_array( $path[ 0 ] , $points ) )
					$points[] = $path[ 0 ];
				if ( !in_array( $path[ 1 ] , $points ) )
					$points[] = $path[ 1 ];
			}
		}
		return $shortest_path;
	}

	private function sort_2d( $records , $field , $reverse = false )
	{
		$hash = array();
		foreach ( $records as $record )
		{
			$hash[ $record[ $field ] ] = $record;
		}
		( $reverse ) ? krsort( $hash ) : ksort( $hash );
		$records = array();
		foreach ( $hash as $record )
		{
			$records []= $record;
		}
		return $records;
	}
}

$adjacency_list = array(
	array(1,2,5),
	array(2,3,4),
	array(4,1,2),
	array(2,1,5),
	array(3,4,3),
	array(1,4,2),
	array(4,2,1)
);

$pa = new KruskalsAlgorithm();

print_r( $pa->shortest_path( $adjacency_list ) );

?>