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<?php |
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namespace TemplesOfCode\NodesAndEdges; |
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use InvalidArgumentException; |
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/** |
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* Class UndirectedGraph |
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* @package TemplesOfCode\NodesAndEdges |
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*/ |
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class UndirectedGraph extends Graph |
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{ |
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/** |
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* Add edge v-w to this graph |
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* |
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* @param int $v |
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* @param int $w |
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*/ |
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public function addEdge(int $v, int $w) |
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{ |
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// validate the vertex |
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Graph::validateVertex($v, $this->vertices); |
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// validate the vertex |
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Graph::validateVertex($v, $this->vertices); |
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// bump |
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$this->edges++; |
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// w is adjacent to v |
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array_unshift($this->adjacencyList[$v], $w); |
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// v is adjacent to w |
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array_unshift($this->adjacencyList[$w], $v); |
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} |
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/** |
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* Initializes a graph from the specified input stream. |
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* |
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* @param string $file |
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* @return UndirectedGraph |
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* @throws InvalidArgumentException |
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*/ |
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public static function fromFile(string $file) |
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{ |
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// open the stream for reading |
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if (!$handle = fopen($file, 'r')) { |
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throw new InvalidArgumentException('could not open stream'); |
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} |
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// fetch from stream |
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$first = fgets($handle); |
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// fetch from stream |
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$second = fgets($handle); |
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// parse V and E |
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list ( |
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$vertices, |
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$edges |
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) = self::parseGraphVEFromString($first, $second); |
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// instantiate a new graph |
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$graph = new UndirectedGraph($vertices); |
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// read in the edges |
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for ($i = 0; $i < $edges; $i++) { |
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// fet from source |
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$raw = fgets($handle); |
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// parse data |
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list ( |
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$v, |
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$w |
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) = self::parseEdge($raw, $vertices); |
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// add to the graph |
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$graph->addEdge($v, $w); |
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} |
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// close the stream |
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fclose($handle); |
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// return the built graph |
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return $graph; |
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} |
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/** |
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* Initializes a new graph that is a deep copy of $g |
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* |
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* @param UndirectedGraph $g |
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* @return UndirectedGraph |
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*/ |
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public static function fromGraph(UndirectedGraph $g) |
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{ |
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// get the number of vertices |
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$vertices = $g->getVertices(); |
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// init |
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$adjacencyList = []; |
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// iterate over the vertices |
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for ($vertex = 0; $vertex < $vertices; $vertex++) { |
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// get the adjacent vertices |
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$adjacencyList[$vertex] = $g->adjacent($vertex); |
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} |
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// return the new graph |
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return new UndirectedGraph($vertices, $adjacencyList); |
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} |
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/** |
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* @param string $graph |
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* @return UndirectedGraph |
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*/ |
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public static function fromString(string $graph) |
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{ |
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// parse the lines |
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$lines = explode("\n", $graph); |
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// parse V and E |
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list ( |
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$vertices, |
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$edges |
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) = self::parseGraphVEFromString($lines[0], $lines[1]); |
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// instantiate a new graph |
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$graph = new UndirectedGraph($vertices); |
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// read in the edges |
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for ($i = 0; $i < $edges; $i++) { |
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// fet from source |
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$raw = $lines[$i+2]; |
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// parse data |
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list ( |
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$v, |
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$w |
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) = self::parseEdge($raw, $vertices); |
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// add to the graph |
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$graph->addEdge($v, $w); |
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} |
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// return the built graph |
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return $graph; |
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} |
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/** |
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* @param resource $handle |
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* @return UndirectedGraph |
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*/ |
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protected static function fromStream($handle) |
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{ |
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// fetch from stream |
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$first = fgets($handle); |
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// fetch from stream |
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$second = fgets($handle); |
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// parse V and E |
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list ( |
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$vertices, |
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$edges |
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) = self::parseGraphVEFromString($first, $second); |
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// instantiate a new graph |
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$graph = new UndirectedGraph($vertices); |
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// read in the edges |
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for ($i = 0; $i < $edges; $i++) { |
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// fet from source |
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$raw = fgets($handle); |
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// parse data |
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list ( |
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$v, |
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$w |
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) = self::parseEdge($raw, $vertices); |
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// add to the graph |
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$graph->addEdge($v, $w); |
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} |
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// close the stream |
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fclose($handle); |
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// return the built graph |
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return $graph; |
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} |
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} |
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templesofcode /
nodes-and-edges
