From 44d663d1768f7a05b14cf60bbe1652a934502f13 Mon Sep 17 00:00:00 2001
From: Dennis Eichhorn <spl1nes.com@googlemail.com>
Date: Sun, 14 Jun 2020 14:54:43 +0200
Subject: [PATCH] implement article affinity analysis

---
 .../Marketing/ArticleCorrelationAffinity.php  | 110 ++++++++++++++++++
 .../ArticleCorrelationAffinityTest.php        |  71 +++++++++++
 2 files changed, 181 insertions(+)
 create mode 100644 Business/Marketing/ArticleCorrelationAffinity.php
 create mode 100644 tests/Business/Marketing/ArticleCorrelationAffinityTest.php

diff --git a/Business/Marketing/ArticleCorrelationAffinity.php b/Business/Marketing/ArticleCorrelationAffinity.php
new file mode 100644
index 000000000..21e4d556c
--- /dev/null
+++ b/Business/Marketing/ArticleCorrelationAffinity.php
@@ -0,0 +1,110 @@
+<?php
+/**
+ * Orange Management
+ *
+ * PHP Version 7.4
+ *
+ * @package   phpOMS\Business\Marketing
+ * @copyright Dennis Eichhorn
+ * @license   OMS License 1.0
+ * @version   1.0.0
+ * @link      https://orange-management.org
+ */
+declare(strict_types=1);
+
+namespace phpOMS\Business\Marketing;
+
+use phpOMS\Math\Statistic\Correlation;
+
+/**
+ * Marketing ArticleAffinity
+ *
+ * This class provided basic marketing metric calculations
+ *
+ * @package phpOMS\Business\Marketing
+ * @license OMS License 1.0
+ * @link    https://orange-management.org
+ * @since   1.0.0
+ */
+final class ArticleCorrelationAffinity
+{
+    /**
+     * Affinity between items
+     *
+     * @var array[]
+     * @since 1.0.0
+     */
+    private array $affinity = [];
+
+    /**
+     * Item order behaviour (when are which items ordered)
+     *
+     * In tearms of the pearson correlation these are our random variables
+     *
+     * @var array
+     * @since 1.0.0
+     */
+    private array $items = [];
+
+    /**
+     * Constructor
+     *
+     * @param array[] $orders           Array of orders which contains as elements the items ordered in the respective order
+     * @param bool    $considerQuantity NOT_IMPLEMENTED!!! Should the quantity be considered
+     *
+     * @since 1.0.0
+     */
+    public function __construct(array $orders, bool $considerQuantity = false)
+    {
+        // find all possible items
+        $possibleItems = [];
+        foreach ($orders as $items) {
+            foreach ($items as $item => $quantity) {
+                if (!\in_array($item, $possibleItems)) {
+                    $possibleItems[] = $item;
+                }
+            }
+        }
+
+        // create the random variables
+        foreach ($orders as $items) {
+            foreach ($possibleItems as $item) {
+                $this->items[$item][] = $items[$item];
+            }
+        }
+
+        // create the affinity table
+        foreach ($possibleItems as $item1) {
+            foreach ($possibleItems as $item2) {
+                if ($item1 !== $item2 &&!isset($this->affinity[$item1][$item2]) && !isset($this->affinity[$item2][$item1])) {
+                    $this->affinity[$item1][$item2] = Correlation::bravaisPersonCorrelationCoefficientPopulation($this->items[$item1], $this->items[$item2]);
+                    $this->affinity[$item2][$item1] = $this->affinity[$item1][$item2];
+                }
+            }
+        }
+
+        // sort correlations
+        foreach ($possibleItems as $item) {
+            \arsort($this->affinity[$item]);
+        }
+    }
+
+    /**
+     * Get the affinity between items
+     *
+     * @param mixed $item       Item to check for possible affinities
+     * @param int   $resultSize How many top matches should be returned
+     *
+     * @return array
+     *
+     * @since 1.0.0
+     */
+    public function getAffinity($item, int $resultSize = 0) : array
+    {
+        if (!isset($this->affinity[$item])) {
+            return [];
+        }
+
+        return $resultSize < 1 ? $this->affinity[$item] : \array_slice($this->affinity[$item], 0, $resultSize);
+    }
+}
diff --git a/tests/Business/Marketing/ArticleCorrelationAffinityTest.php b/tests/Business/Marketing/ArticleCorrelationAffinityTest.php
new file mode 100644
index 000000000..9f53e484a
--- /dev/null
+++ b/tests/Business/Marketing/ArticleCorrelationAffinityTest.php
@@ -0,0 +1,71 @@
+<?php
+/**
+ * Orange Management
+ *
+ * PHP Version 7.4
+ *
+ * @package   tests
+ * @copyright Dennis Eichhorn
+ * @license   OMS License 1.0
+ * @version   1.0.0
+ * @link      https://orange-management.org
+ */
+declare(strict_types=1);
+
+namespace phpOMS\tests\Business\Marketing;
+
+use phpOMS\Business\Marketing\ArticleCorrelationAffinity;
+
+/**
+ * @testdox phpOMS\tests\Business\Marketing\ArticleCorrelationAffinityTest: Article affinity/correlation
+ *
+ * @internal
+ */
+class ArticleCorrelationAffinityTest extends \PHPUnit\Framework\TestCase
+{
+    /**
+     * @testdox The highest affinities between articles purchased are calculated correctly
+     * @group framework
+     */
+    public function testAffinity() : void
+    {
+        $orders = [
+            ['A' => 1, 'B' => 1, 'C' => 0, 'D' => 0],
+            ['A' => 0, 'B' => 1, 'C' => 0, 'D' => 0],
+            ['A' => 1, 'B' => 1, 'C' => 0, 'D' => 0],
+            ['A' => 1, 'B' => 0, 'C' => 0, 'D' => 1],
+            ['A' => 0, 'B' => 0, 'C' => 0, 'D' => 0],
+            ['A' => 1, 'B' => 1, 'C' => 0, 'D' => 0],
+            ['A' => 1, 'B' => 0, 'C' => 1, 'D' => 0],
+            ['A' => 0, 'B' => 0, 'C' => 1, 'D' => 0],
+            ['A' => 1, 'B' => 1, 'C' => 0, 'D' => 0],
+            ['A' => 1, 'B' => 1, 'C' => 0, 'D' => 0],
+            ['A' => 0, 'B' => 1, 'C' => 0, 'D' => 0],
+            ['A' => 0, 'B' => 1, 'C' => 0, 'D' => 0],
+            ['A' => 1, 'B' => 1, 'C' => 0, 'D' => 0],
+            ['A' => 0, 'B' => 0, 'C' => 0, 'D' => 0],
+            ['A' => 0, 'B' => 0, 'C' => 0, 'D' => 0],
+        ];
+
+        $aff = new ArticleCorrelationAffinity($orders);
+
+        self::assertEqualsWithDelta(
+            [
+                'A' => 0.3273,
+                'C' => -0.4803,
+                'D' => -0.3273,
+            ],
+            $aff->getAffinity('B'),
+            0.001
+        );
+
+        self::assertEqualsWithDelta(
+            [
+                'A' => 0.3273,
+                'D' => -0.3273,
+            ],
+            $aff->getAffinity('B', 2),
+            0.001
+        );
+    }
+}