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Implement Algorithm\Tree\Undirected + 100% code coverage
1 parent 0513d3d commit af6ce61

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2 files changed

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‎src/Tree/Undirected.php

Lines changed: 67 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -8,6 +8,8 @@
88
use Fhaculty\Graph\Algorithm\Search\Base as Search;
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use Fhaculty\Graph\Algorithm\Search\StrictDepthFirst;
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use Fhaculty\Graph\Vertex;
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use Fhaculty\Graph\Edge\Base as Edge;
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use Fhaculty\Graph\Edge\UndirectedId as UndirectedEdge;
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/**
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* Undirected tree implementation
@@ -41,6 +43,14 @@
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*/
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class Undirected extends Tree
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{
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/**
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* checks if this is a tree
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*
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* @return boolean
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* @uses Graph::isEmpty() to skip empty Graphs (an empty Graph is a valid tree)
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* @uses Graph::getVertexFirst() to get get get random "root" Vertex to start search from
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* @uses self::getVerticesSubtreeRecursive() to count number of vertices connected to root
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*/
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public function isTree()
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{
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if ($this->graph->isEmpty()) {
@@ -50,8 +60,13 @@ public function isTree()
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// every vertex can represent a root vertex, so just pick one
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$root = $this->graph->getVertexFirst();
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// TODO: recurse $root to get sub-vertices
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$vertices = array();
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try {
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$this->getVerticesSubtreeRecursive($root, $vertices, null);
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}
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catch (UnexpectedValueException $e) {
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return false;
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}
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return (count($vertices) === $this->graph->getNumberOfVertices());
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}
@@ -79,4 +94,55 @@ public function isVertexInternal(Vertex $vertex)
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{
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return ($vertex->getDegree() >= 2);
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}
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/**
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* get subtree for given Vertex and ignore path to "parent" ignoreVertex
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*
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* @param Vertex $vertex
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* @param Vertex[] $vertices
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* @param Vertex|null $ignore
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* @throws UnexpectedValueException for cycles or directed edges (check isTree()!)
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* @uses self::getVerticesNeighboor()
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* @uses self::getVerticesSubtreeRecursive() to recurse into sub-subtrees
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*/
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private function getVerticesSubtreeRecursive(Vertex $vertex, &$vertices, Vertex $ignore = null)
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{
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if (isset($vertices[$vertex->getId()])) {
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// vertex already visited => must be a cycle
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throw new UnexpectedValueException('Vertex already visited');
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}
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$vertices[$vertex->getId()] = $vertex;
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foreach ($this->getVerticesNeighboor($vertex) as $vertexNeighboor) {
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if ($vertexNeighboor === $ignore) {
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// ignore source vertex only once
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$ignore = null;
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continue;
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}
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$this->getVerticesSubtreeRecursive($vertexNeighboor, $vertices, $vertex);
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}
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}
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/**
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* get neighboor vertices for given start vertex
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*
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* @param Vertex $vertex
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* @throws UnexpectedValueException for directed edges
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* @return Vertex[] (might include possible duplicates)
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* @uses Vertex::getEdges()
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* @uses Edge::getVertexToFrom()
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* @see Vertex::getVerticesEdge()
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*/
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private function getVerticesNeighboor(Vertex $vertex)
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{
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$vertices = array();
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foreach ($vertex->getEdges() as $edge) {
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/* @var Edge $edge */
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if (!($edge instanceof UndirectedEdge)) {
142+
throw new UnexpectedValueException('Directed edge encountered');
143+
}
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$vertices[] = $edge->getVertexToFrom($vertex);
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}
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return $vertices;
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}
82148
}

‎tests/Tree/UndirectedTest.php

Lines changed: 114 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,114 @@
1+
<?php
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use Fhaculty\Graph\Graph;
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use Fhaculty\Graph\Algorithm\Tree\Undirected;
6+
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class UndirectedTest extends TestCase
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{
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protected function createTree(Graph $graph)
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{
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return new Undirected($graph);
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}
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public function testGraphEmpty()
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{
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$graph = new Graph();
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$tree = $this->createTree($graph);
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$this->assertTrue($tree->isTree());
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$this->assertSame(array(), $tree->getVerticesInternal());
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$this->assertSame(array(), $tree->getVerticesLeaf());
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}
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public function testGraphTrivial()
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{
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$graph = new Graph();
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$graph->createVertex('v1');
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$tree = $this->createTree($graph);
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$this->assertTrue($tree->isTree());
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$this->assertSame(array(), $tree->getVerticesInternal());
33+
$this->assertSame(array(), $tree->getVerticesLeaf());
34+
}
35+
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public function testGraphSimplePair()
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{
38+
// v1 -- v2
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$graph = new Graph();
40+
$graph->createVertex('v1')->createEdge($graph->createVertex('v2'));
41+
42+
$tree = $this->createTree($graph);
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$this->assertTrue($tree->isTree());
44+
$this->assertSame(array(), $tree->getVerticesInternal());
45+
$this->assertSame($graph->getVertices(), $tree->getVerticesLeaf());
46+
}
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public function testGraphSimpleLine()
49+
{
50+
// v1 -- v2 -- v3
51+
$graph = new Graph();
52+
$graph->createVertex('v1')->createEdge($graph->createVertex('v2'));
53+
$graph->getVertex('v2')->createEdge($graph->createVertex('v3'));
54+
55+
$tree = $this->createTree($graph);
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$this->assertTrue($tree->isTree());
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$this->assertSame(array($graph->getVertex('v2')), array_values($tree->getVerticesInternal()));
58+
$this->assertSame(array($graph->getVertex('v1'), $graph->getVertex('v3')), array_values($tree->getVerticesLeaf()));
59+
}
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61+
public function testGraphPairParallelIsNotTree()
62+
{
63+
// v1 -- v2 -- v1
64+
$graph = new Graph();
65+
$graph->createVertex('v1')->createEdge($graph->createVertex('v2'));
66+
$graph->getVertex('v1')->createEdge($graph->getVertex('v2'));
67+
68+
$tree = $this->createTree($graph);
69+
$this->assertFalse($tree->isTree());
70+
}
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public function testGraphLoopIsNotTree()
73+
{
74+
// v1 -- v1
75+
$graph = new Graph();
76+
$graph->createVertex('v1')->createEdge($graph->getVertex('v1'));
77+
78+
$tree = $this->createTree($graph);
79+
$this->assertFalse($tree->isTree());
80+
}
81+
82+
public function testGraphCycleIsNotTree()
83+
{
84+
// v1 -- v2 -- v3 -- v1
85+
$graph = new Graph();
86+
$graph->createVertex('v1')->createEdge($graph->createVertex('v2'));
87+
$graph->getVertex('v2')->createEdge($graph->createVertex('v3'));
88+
$graph->getVertex('v3')->createEdge($graph->getVertex('v1'));
89+
90+
$tree = $this->createTree($graph);
91+
$this->assertFalse($tree->isTree());
92+
}
93+
94+
public function testGraphDirectedIsNotTree()
95+
{
96+
// v1 -> v2
97+
$graph = new Graph();
98+
$graph->createVertex('v1')->createEdgeTo($graph->createVertex('v2'));
99+
100+
$tree = $this->createTree($graph);
101+
$this->assertFalse($tree->isTree());
102+
}
103+
104+
public function testGraphMixedIsNotTree()
105+
{
106+
// v1 -- v2 -> v3
107+
$graph = new Graph();
108+
$graph->createVertex('v1')->createEdge($graph->createVertex('v2'));
109+
$graph->getVertex('v2')->createEdgeTo($graph->createVertex('v3'));
110+
111+
$tree = $this->createTree($graph);
112+
$this->assertFalse($tree->isTree());
113+
}
114+
}

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