https://github.com/devtronic/tree-classifier
A class for decision trees
https://github.com/devtronic/tree-classifier
decision-tree php
Last synced: 9 months ago
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A class for decision trees
- Host: GitHub
- URL: https://github.com/devtronic/tree-classifier
- Owner: devtronic
- License: lgpl-3.0
- Created: 2016-12-09T18:46:57.000Z (over 9 years ago)
- Default Branch: master
- Last Pushed: 2016-12-09T22:25:46.000Z (over 9 years ago)
- Last Synced: 2025-05-24T09:07:02.783Z (about 1 year ago)
- Topics: decision-tree, php
- Language: PHP
- Homepage:
- Size: 8.79 KB
- Stars: 10
- Watchers: 2
- Forks: 1
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
- License: LICENSE
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# Tree Classifier
A PHP Library for decision trees
### What is a decision tree?
This (really basic): 
### Code Example
In this example we classify 10 Persons. We want to find all males under 50 years old who can cook and don't playing football
```php
['gender' => 'male', 'age' => 41, 'playsFootball' => 'nope', 'canCook' => 'nope'],
1 => ['gender' => 'female', 'age' => 91, 'playsFootball' => 'nope', 'canCook' => 'nope'],
2 => ['gender' => 'male', 'age' => 17, 'playsFootball' => 'nope', 'canCook' => 'yes'],
3 => ['gender' => 'female', 'age' => 39, 'playsFootball' => 'nope', 'canCook' => 'yes'],
4 => ['gender' => 'male', 'age' => 90, 'playsFootball' => 'nope', 'canCook' => 'yes'],
5 => ['gender' => 'male', 'age' => 51, 'playsFootball' => 'nope', 'canCook' => 'yes'],
6 => ['gender' => 'male', 'age' => 86, 'playsFootball' => 'yes', 'canCook' => 'nope'],
7 => ['gender' => 'male', 'age' => 99, 'playsFootball' => 'yes', 'canCook' => 'yes'],
8 => ['gender' => 'female', 'age' => 39, 'playsFootball' => 'nope', 'canCook' => 'yes'],
9 => ['gender' => 'female', 'age' => 37, 'playsFootball' => 'yes', 'canCook' => 'yes'],
];
// Find all
// - males
// - under 50
// - can cook
// - does not play football
// Create from bottom up
// We want all subjects who don't play football
$footballDecisions = [
'play' => new TerminalNode(),
'does not play' => new TerminalNode(), // This is our last node
];
// Create the decider for football
$footballDecider = new DecisionNode(function ($subject) {
// This is our decider function, $subject is the current object
// in the queue of the current node.
// Return the key of our $footballDecision-Array
return ($subject['playsFootball'] == 'yes' ? 'play' : 'does not play');
}, $footballDecisions);
// Great, next we need the cook-decisions.
$cookDecisions = [
'can cook' => $footballDecider, // redirect all subjects who can cook to the $footballDecider
'can not cook' => new TerminalNode(),
];
// Now the cookDecider
$cookDecider = new DecisionNode(function ($subject) {
return ($subject['canCook'] == 'yes' ? 'can cook' : 'can not cook');
}, $cookDecisions);
// The same as previous for the next 2 decisions
$ageDecisions = [
'< 50' => $cookDecider,
'>= 50' => new TerminalNode(),
];
$ageDecider = new DecisionNode(function ($subject) {
return ($subject['age'] >= 50 ? '>= 50' : '< 50');
}, $ageDecisions);
$genderDecisions = [
'male' => $ageDecider,
'female' => new TerminalNode(),
];
$genderDecider = new DecisionNode(function ($subject) {
return $subject['gender'];
}, $genderDecisions);
// And now we need to create a RootNode
$rootNode = new RootNode($subjects);
// Add the first (last created) node to our RootNode:
$rootNode->addSubNode($genderDecider);
// And classify
$rootNode->classify();
// In $footballDecisions['does not play'] are our subjects there we looked for:
print_r($footballDecisions['does not play']);
// Outputs
// Array
// (
// [0] => Array
// (
// [gender] => male
// [age] => 17
// [playsFootball] => nope
// [canCook] => yes
// )
// )
// Explanation:
// [0, 1, 2, 3, 4, 5, 6, 7, 8, 9] = Keys from $subjects-Array
// \_________ RootNode _________/
// |
// /------ Gender Decider ------\
// | |
// Female Male
// [1, 3, 8, 9] [0, 2, 4, 5, 6, 7]
// | |
// Terminal Node |
// /----- Age Decider -----\
// | |
// >= 50 < 50
// [4, 5, 6, 7] [0, 2]
// | |
// Terminal Node |
// /---- Cook Decider ----\
// | |
// Can not cook Can cook
// [0] [2]
// | |
// Terminal Node |
// /---- Football Decider ----\
// | |
// play does not play
// [ ] [2]
// | |
// Terminal Node Terminal Node
```