166 lines
3.7 KiB
PHP
166 lines
3.7 KiB
PHP
<?php
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declare(strict_types=1);
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namespace Phpml\Classification\DecisionTree;
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use Phpml\Math\Comparison;
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class DecisionTreeLeaf
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{
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/**
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* @var string|int
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*/
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public $value;
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/**
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* @var float
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*/
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public $numericValue;
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/**
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* @var string
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*/
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public $operator;
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/**
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* @var int
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*/
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public $columnIndex;
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/**
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* @var DecisionTreeLeaf|null
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*/
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public $leftLeaf;
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/**
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* @var DecisionTreeLeaf|null
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*/
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public $rightLeaf;
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/**
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* @var array
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*/
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public $records = [];
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/**
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* Class value represented by the leaf, this value is non-empty
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* only for terminal leaves
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*
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* @var string
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*/
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public $classValue = '';
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/**
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* @var bool
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*/
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public $isTerminal = false;
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/**
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* @var bool
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*/
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public $isContinuous = false;
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/**
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* @var float
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*/
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public $giniIndex = 0;
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/**
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* @var int
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*/
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public $level = 0;
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/**
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* HTML representation of the tree without column names
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*/
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public function __toString(): string
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{
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return $this->getHTML();
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}
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public function evaluate(array $record): bool
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{
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$recordField = $record[$this->columnIndex];
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if ($this->isContinuous) {
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return Comparison::compare((string) $recordField, $this->numericValue, $this->operator);
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}
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return $recordField == $this->value;
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}
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/**
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* Returns Mean Decrease Impurity (MDI) in the node.
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* For terminal nodes, this value is equal to 0
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*/
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public function getNodeImpurityDecrease(int $parentRecordCount): float
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{
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if ($this->isTerminal) {
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return 0.0;
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}
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$nodeSampleCount = (float) count($this->records);
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$iT = $this->giniIndex;
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if ($this->leftLeaf !== null) {
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$pL = count($this->leftLeaf->records) / $nodeSampleCount;
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$iT -= $pL * $this->leftLeaf->giniIndex;
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}
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if ($this->rightLeaf !== null) {
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$pR = count($this->rightLeaf->records) / $nodeSampleCount;
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$iT -= $pR * $this->rightLeaf->giniIndex;
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}
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return $iT * $nodeSampleCount / $parentRecordCount;
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}
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/**
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* Returns HTML representation of the node including children nodes
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*/
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public function getHTML(?array $columnNames = null): string
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{
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if ($this->isTerminal) {
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$value = "<b>{$this}->classValue</b>";
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} else {
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$value = $this->value;
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if ($columnNames !== null) {
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$col = $columnNames[$this->columnIndex];
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} else {
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$col = "col_$this->columnIndex";
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}
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if ((bool) preg_match('/^[<>=]{1,2}/', (string) $value) === false) {
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$value = "={$value}";
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}
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$value = "<b>{$col} {$value}</b><br>Gini: ".number_format($this->giniIndex, 2);
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}
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$str = "<table ><tr><td colspan=3 align=center style='border:1px solid;'>{$value}</td></tr>";
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if ($this->leftLeaf !== null || $this->rightLeaf !== null) {
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$str .= '<tr>';
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if ($this->leftLeaf !== null) {
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$str .= '<td valign=top><b>| Yes</b><br>'.$this->leftLeaf->getHTML($columnNames).'</td>';
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} else {
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$str .= '<td></td>';
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}
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$str .= '<td> </td>';
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if ($this->rightLeaf !== null) {
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$str .= '<td valign=top align=right><b>No |</b><br>'.$this->rightLeaf->getHTML($columnNames).'</td>';
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} else {
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$str .= '<td></td>';
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}
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$str .= '</tr>';
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}
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$str .= '</table>';
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return $str;
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}
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}
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