1: 2: 3: 4: 5: 6: 7: 8: 9: 10: 11: 12: 13: 14: 15: 16: 17: 18: 19: 20: 21: 22: 23: 24: 25: 26: 27: 28: 29: 30: 31: 32: 33: 34: 35: 36: 37: 38: 39: 40: 41: 42: 43: 44: 45: 46: 47: 48: 49: 50: 51: 52: 53: 54: 55: 56: 57: 58: 59: 60: 61: 62: 63: 64: 65: 66: 67: 68: 69: 70: 71: 72: 73: 74: 75: 76: 77: 78: 79: 80: 81: 82: 83: 84: 85: 86: 87: 88: 89: 90: 91: 92: 93: 94: 95: 96: 97: 98: 99: 100: 101: 102: 103: 104: 105: 106: 107: 108: 109: 110: 111: 112: 113: 114: 115: 116: 117: 118: 119: 120: 121: 122: 123: 124: 125: 126: 127: 128: 129: 130:
<?php
namespace Chippyash\Math\Matrix\Derivative;
use Chippyash\Math\Matrix\Exceptions\MathMatrixException;
use Chippyash\Math\Matrix\Exceptions\NotMarkovException;
use Chippyash\Math\Matrix\NumericMatrix;
use Chippyash\Math\Type\Calculator;
use Chippyash\Math\Type\Comparator;
use Chippyash\Type\Interfaces\NumericTypeInterface;
use Chippyash\Type\Number\IntType;
use Chippyash\Type\TypeFactory;
use Assembler\FFor;
use Monad\FTry;
class MarkovWeightedRandom extends AbstractDerivative
{
protected $comp;
protected $calc;
protected $zero;
public function derive(NumericMatrix $mA, $extra = null)
{
if (!$mA->is('Markov')) {
throw new NotMarkovException();
}
if (!$extra instanceof IntType) {
throw new MathMatrixException('The extra parameter is not an IntType');
}
$this->comp = new Comparator();
$this->calc = new Calculator();
$this->zero = TypeFactory::createInt(0);
return $this->nextWeightedRandom($mA, $extra);
}
protected function nextWeightedRandom(NumericMatrix $mA, NumericTypeInterface $current)
{
$array = FFor::create(['row' => $current, 'mA' => $mA])
->slice(function($row, $mA) {$t = $mA('Rowslice', [$row()])->toArray(); return array_pop($t);})
->array(function($slice) {
return array_filter(
$slice,
function ($item) {
return $this->comp->neq($this->zero, $item);
}
);
})
->fyield('array');
if (count($array) <= 1) {
return TypeFactory::createInt(key($array));
}
$sum = (new NumericMatrix([$array]))->derive(new Sum())->asIntType();
if ($this->comp->lte($sum, $this->zero)) {
throw new MathMatrixException('Negative or all-zero weights not allowed');
}
return $this->getNextRow($sum, $array);;
}
protected function getNextRow($sum, $rowArray)
{
return FFor::create(['sum' => $sum, 'rowArray' => $rowArray])
->targetWeight(function($sum) {
return TypeFactory::createInt(mt_rand(1, $sum()));
})
->nextRow(function($targetWeight, $rowArray) {
foreach ($rowArray as $key => $weight) {
if ($this->comp->lt($weight, $this->zero)) {
throw new MathMatrixException('Negative weights not allowed');
}
$targetWeight = $this->calc->sub($targetWeight, $weight);
if ($this->comp->lte($targetWeight, $this->zero)) {
return TypeFactory::createInt($key + 1);
}
}
})
->fyield('nextRow');
}
}