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<?php |
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/** |
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* Simplify Polyline with the Douglas-Peucker-Algorithm |
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* |
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* The Algorithm is described here: |
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* http://en.wikipedia.org/wiki/Ramer%E2%80%93Douglas%E2%80%93Peucker_algorithm |
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* |
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* The formula for the Perpendicular Distance is described here: |
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* http://biodiversityinformatics.amnh.org/open_source/pdc/documentation.php |
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* |
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* @author Marcus Jaschen <[email protected]> |
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* @license https://opensource.org/licenses/GPL-3.0 GPL |
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* @link https://github.com/mjaschen/phpgeo |
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*/ |
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namespace Location\Processor\Polyline; |
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use Location\Line; |
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use Location\Polyline; |
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use Location\Utility\PerpendicularDistance; |
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/** |
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* Simplify Polyline with the Douglas-Peucker-Algorithm |
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* |
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* @author Marcus Jaschen <[email protected]> |
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* @license https://opensource.org/licenses/GPL-3.0 GPL |
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* @link https://github.com/mjaschen/phpgeo |
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*/ |
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class SimplifyDouglasPeucker implements SimplifyInterface |
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{ |
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/** |
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* @var float |
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*/ |
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private $tolerance; |
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/** |
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* @param float $tolerance the perpendicular distance threshold in meters |
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*/ |
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public function __construct($tolerance) |
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{ |
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$this->tolerance = $tolerance; |
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} |
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/** |
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* @param \Location\Polyline $polyline |
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* |
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* @return \Location\Polyline |
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*/ |
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public function simplify(Polyline $polyline) |
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{ |
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$resultPolyline = new Polyline(); |
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$simplifiedLine = $this->douglasPeucker($polyline->getPoints()); |
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foreach ($simplifiedLine as $point) { |
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$resultPolyline->addPoint($point); |
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} |
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return $resultPolyline; |
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} |
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/** |
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* @param array $line |
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* |
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* @return array |
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*/ |
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View Code Duplication |
protected function douglasPeucker(array $line) |
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{ |
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$distanceMax = 0; |
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$index = 0; |
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$lineSize = count($line); |
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$pdCalc = new PerpendicularDistance(); |
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for ($i = 1; $i <= ($lineSize - 1); $i ++) { |
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$distance = $pdCalc->getPerpendicularDistance($line[$i], new Line($line[0], $line[$lineSize - 1])); |
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if ($distance > $distanceMax) { |
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$index = $i; |
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$distanceMax = $distance; |
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} |
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} |
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if ($distanceMax > $this->tolerance) { |
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$lineSplitFirst = array_slice($line, 0, $index); |
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$lineSplitSecond = array_slice($line, $index, $lineSize); |
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$resultsSplit1 = $this->douglasPeucker($lineSplitFirst); |
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$resultsSplit2 = $this->douglasPeucker($lineSplitSecond); |
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array_pop($resultsSplit1); |
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return array_merge($resultsSplit1, $resultsSplit2); |
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} |
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return [$line[0], $line[$lineSize - 1]]; |
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} |
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} |
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mjaschen /
phpgeo
Duplicated code is one of the most pungent code smells. If you need to duplicate the same code in three or more different places, we strongly encourage you to look into extracting the code into a single class or operation.
You can also find more detailed suggestions in the “Code” section of your repository.