/**
  * Measurement Update Function
  *
  * That's where we are scanning the world trying to find the place where are at.
  * Updates the internal probability matrix
  *
  * @param $input
  * @param Robot $robot
  * @return $this
  */
 public function sense($input, Robot $robot)
 {
     $retVal = [];
     // Update measurement
     foreach ($robot->getProbabilityMatrix() as $index => $p) {
         if ($input == $robot->getWorld()[$index]) {
             $retVal[] = $robot->getPHit() * $p;
         } else {
             $retVal[] = $robot->getPMiss() * $p;
         }
     }
     // Normalize data
     $normalisationFactor = array_sum($retVal);
     foreach ($retVal as $index => $value) {
         $retVal[$index] = $retVal[$index] * (1 / $normalisationFactor);
     }
     $robot->setProbabilityMatrix($retVal);
     return $this;
 }