update

composer.json

@@ -0,0 +1,34 @@
+{
+    "name": "tigo/recommendation",
+    "description": "collaborative filtering recommender systems", 
+    "license": "MIT",
+    "keywords": [  
+       "recommendation",
+       "collaborative filtering",
+       "euclidean distance",
+       "recommender system",
+       "recommendation system",
+       "recommendation algorithm",
+       "recommender"   
+    ],
+    "authors": [ 
+        {
+            "name": "Tiago A C Pereira",
+            "email": "[email protected]"
+        }
+    ],
+    "require": {
+        "php": ">=7.0"
+    },
+    "autoload": {
+        "psr-4": {
+            "Tigo\\Recommendation\\": "src/" 
+        }
+    },
+    "autoload-dev": {
+        "psr-4": { "Tigo\\Recommendation\\Tests\\": "tests" }
+    },
+    "require-dev": {
+        "phpunit/phpunit": "^9.5"
+    }
+}

phpunit.xml

@@ -0,0 +1,12 @@
+<?xml version="1.0" encoding="UTF-8"?>
+
+     <phpunit bootstrap="vendor/autoload.php"
+            colors="true"
+            verbose="true"
+            stopOnFailure="false">
+        <testsuites>
+            <testsuite name="result">
+                <directory>tests</directory>
+            </testsuite>
+        </testsuites>
+    </phpunit>

src/Collaborative/Base.php

@@ -0,0 +1,64 @@
+<?php
+namespace Tigo\Recommendation\Collaborative;
+
+use Tigo\Recommendation\Configuration\StandardKey;
+use Tigo\Recommendation\Interfaces\CollaborativeInterface;
+
+/**
+ * [Base]
+ * 
+ * @author Tiago A C Pereira <[email protected]>
+ */
+abstract class Base extends StandardKey implements CollaborativeInterface
+{
+
+    /**
+     * User rated product.
+     * @var array
+     */
+    protected $product = []; 
+
+    /**
+     * Product rated by other users. 
+     * @var array
+     */
+    protected $other = []; 
+
+   /**
+    * Get rated product.
+    * @param array $table
+    * @param mixed $user
+    * 
+    * @return [type]
+    */
+    protected function ratedProduct($table, $user) 
+    { 
+        foreach($table as $item){
+            $item[self::USER_ID] == $user ?  $this->product[] = $item : $this->other[] = $item;   
+        }  
+    }
+
+
+    /**
+     * Get filter rating.
+     * Remove product that the user has rated.
+     * @param array $data
+     * 
+     * @return array
+     */
+    protected function filterRating($data)
+    {
+        $myRank = $data;  
+        $rank = $myRank;  
+        for($i = 0; $i < count($myRank); $i++){    
+            foreach($this->product as $item){           
+                if($item[self::PRODUCT_ID] == key($myRank))
+                    unset($rank[key($myRank)]); // remove product
+            } 
+            next($myRank);
+        }  
+        arsort($rank);
+        return $rank;  
+    } 
+
+}

src/Collaborative/EuclideanCollaborative.php

@@ -0,0 +1,138 @@
+<?php
+namespace Tigo\Recommendation\Collaborative;
+
+use Tigo\Recommendation\Collaborative\Base;
+use Tigo\Recommendation\Traits\OperationTrait;
+
+/**
+ * Collaborative filtering [recommendation algorithm EuclideanCollaborative].
+ * Using the Euclidean distance formula and applying a weighted average.
+ * 
+ * @author Tiago A C Pereira <[email protected]>
+ */
+class EuclideanCollaborative extends Base
+{
+
+    use OperationTrait;
+
+    /**
+     * Get recommend.
+     * @param array $table
+     * @param mixed $user
+     * @param mixed $score
+     * 
+     * @return array
+     */
+    public function recommend($table, $user, $score = 0)  
+    { 
+        $data = $this->average($table, $user, $score);
+        return $this->filterRating($data);   
+    }
+
+    /**
+     * Get users who rated the same product.
+     * @param array $table
+     * @param mixed $user
+     * @param mixed $score
+     * 
+     * @return array
+     */
+    private function userRated($table, $user, $score)
+    {
+        $this->ratedProduct($table, $user);
+        $rated = []; //get user rating
+        foreach($this->product as $myProduct){
+            foreach($this->other as $item){ 
+               if($myProduct[self::PRODUCT_ID] == $item[self::PRODUCT_ID]){
+                   if($myProduct[self::SCORE] >= $score && $item[self::SCORE] >= $score){
+                      if(!in_array($item[self::USER_ID],$rated)) // check if user already exists
+                          $rated[] = $item[self::USER_ID]; //add user
+                   }     
+               }
+            }
+        }
+        return $rated;
+    }
+
+    /**
+     * Get operation|using part of the euclidean formula (p-q).
+     * @param array $table
+     * @param mixed $user
+     * @param mixed $score
+     * 
+     * @return array
+     */
+    private function operation($table, $user, $score)
+    {
+        $rated = $this->userRated($table, $user, $score);
+        $data = [];
+        foreach ($this->product as $myProduct){
+            for($i = 0; $i < count($rated) ; $i++){
+                foreach($this->other as $itemOther){
+                    if($itemOther[self::USER_ID] == $rated[$i] &&
+                    $myProduct[self::PRODUCT_ID] == $itemOther[self::PRODUCT_ID] 
+                    && $myProduct[self::SCORE] >= $score && $itemOther[self::SCORE] >= $score){  
+                        $data[$itemOther[self::USER_ID]][$myProduct[self::PRODUCT_ID]] = abs($itemOther[self::SCORE] - $myProduct[self::SCORE]);       
+                    }  
+                }
+            }
+        }
+        return $data;
+    }
+
+    /**
+     * Using the metric distance formula and convert value to percentage.
+     * @param array $table
+     * @param mixed $user
+     * @param mixed $score
+     *  
+     * @return array
+     */
+    private function metricDistance($table, $user, $score)
+    {
+        $data = $this->operation($table, $user, $score);
+        $element = [];
+        foreach($data as $item){
+            foreach($item as $value){
+                if(!isset($element[key($data)]))
+                    $element[key($data)] = 0;
+                $element[key($data)] += pow($value,2);
+            }
+            $similarity = round(sqrt($element[key($data)]),2); //similarity rate
+            $element[key($data)] =  round(1/(1 + $similarity), 2); //convert value
+            next($data);
+        }     
+        return $element;
+    }
+
+
+    /**
+     * Get weighted average.
+     * @param array $table 
+     * @param mixed $user
+     * @param mixed $score
+     * 
+     * @return array
+     */
+    private function average($table, $user, $score)
+    {
+        $metric = $this->metricDistance($table, $user, $score);
+        $similarity = [];
+        $element = [];
+        foreach($metric as $itemMetric){
+            foreach($this->other as $itemOther){
+                if($itemOther[self::USER_ID] == key($metric) && $itemOther[self::SCORE] >= $score){
+                    if(!isset($element[$itemOther[self::PRODUCT_ID]])){
+                       $element[$itemOther[self::PRODUCT_ID]] = 0;
+                       $similarity[$itemOther[self::PRODUCT_ID]] = 0;
+                    }     
+                   $element[$itemOther[self::PRODUCT_ID]] += ($itemMetric * $itemOther[self::SCORE]); 
+                   $similarity[$itemOther[self::PRODUCT_ID]] += $itemMetric; 
+                }
+            }
+           next($metric);  
+        }
+        return $this->division($element,$similarity);
+    }
+
+}

src/Collaborative/RankingCollaborative.php

@@ -0,0 +1,85 @@
+<?php
+namespace Tigo\Recommendation\Collaborative;
+
+use Tigo\Recommendation\Collaborative\Base;
+
+/**
+ * Collaborative filtering [recommendation algorithm RankingCollaborative].
+ * The algorithm checks for similar ratings compared to other users,
+ * and adds a weight score and generate a rating for each product.
+ * Example: user1 liked [A, B, C, D] and user2 liked [A, B] 
+ * recommend product [C, D] to user2 (product score = [C = 2 ; D = 2]).  
+ * 
+ * @author Tiago A C Pereira <[email protected]>
+ */
+class RankingCollaborative extends Base
+{
+
+    /**
+     * Get Recommend.  
+     * @param array $table
+     * @param mixed $user
+     * @param mixed $score
+     * 
+     * @return array
+     */
+    public function recommend($table, $user, $score = 0)
+    {  
+        $data = $this->addRating($table, $user, $score);
+        return $this->filterRating($data);     
+    }
+
+    /**
+     * Find similar users (Add weight score).
+     * @param array $table
+     * @param mixed $user
+     * 
+     * @return array
+     */ 
+    private function similarUser($table, $user)
+    {
+        $this->ratedProduct($table, $user); //get [product, other]    
+        $similar = []; //get users with similar tastes
+        $rank = [];
+        foreach($this->product as $myProduct){
+            foreach($this->other as $item){ 
+               if($myProduct[self::PRODUCT_ID] == $item[self::PRODUCT_ID]){
+                   if($myProduct[self::SCORE] == $item[self::SCORE]){
+                      if(!isset($similar[$item[self::USER_ID]])) 
+                          $similar[$item[self::USER_ID]] = 0; //
+                      $similar[$item[self::USER_ID]] += 1; //assigning weight     
+                   }     
+               }
+            }
+        }
+        return $similar;  
+    }
+
+
+    /**
+     * Add Rating | Add a score (+value) for each recommended product.
+     * @param array $table
+     * @param mixed $user
+     * @param mixed $score
+     * 
+     * @return array
+     */
+    private function addRating($table, $user, $score) 
+    {
+        $similar =  $this->similarUser($table, $user);
+        $rank = [];
+        foreach($this->other as $item){
+            foreach($similar as $value){
+               if($item[self::USER_ID] == key($similar) && $item[self::SCORE] > $score){
+                   if(!isset($rank[$item[self::PRODUCT_ID]]) )
+                       $rank[$item[self::PRODUCT_ID]] = 0; //assign value for calculation
+                   $rank[$item[self::PRODUCT_ID]] += $value; //add   
+               }
+               next($similar);
+            }
+            reset($similar);     
+        }
+        return $rank;
+    }
+
+}

src/Configuration/StandardKey.php

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+<?php 
+namespace Tigo\Recommendation\Configuration;
+
+abstract class StandardKey
+{
+    const SCORE = 'score'; //score  
+    const PRODUCT_ID = 'product_id'; //Foreign key
+    const USER_ID = 'user_id'; //Foreign key 
+}

src/Creator/CollaborativeCreator.php

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+<?php
+namespace Tigo\Recommendation\Creator;
+
+use Tigo\Recommendation\Interfaces\CollaborativeInterface;
+
+abstract class CollaborativeCreator
+{
+
+ /**
+  * @param CollaborativeInterface $col
+  * @param array $table
+  * @param mixed $user
+  * @param mixed $score
+  * 
+  * @return [type]
+  */
+    protected abstract function factoryMethod(CollaborativeInterface $col, $table, $user, $score);
+
+    /**
+     * @param CollaborativeInterface $method
+     * @param array $table
+     * @param mixed $user
+     * @param mixed $score
+     * 
+     * @return [type]
+     */
+    public function doFactory($method, $table, $user, $score)
+    {
+       return $this->factoryMethod($method, $table, $user, $score); 
+    }
+
+}