20 MEDIUM Content-Based Algorithm Projects

Introduction to Advanced Content-Based Algorithms

Content-based recommendation systems have evolved significantly, incorporating sophisticated techniques like natural language processing, deep learning embeddings, and hybrid approaches. These systems analyze item content and user preferences to generate highly personalized recommendations.

Advanced Techniques Covered:

  1. TF-IDF Vectorization - Converting text to numerical vectors
  2. Word Embeddings - Semantic understanding of content
  3. Multi-modal Features - Combining different content types
  4. Real-time Learning - Adaptive user profiling
  5. Contextual Bandits - Exploration vs exploitation

20 Advanced Content-Based Algorithm Projects

Project 21: Semantic Article Recommender

Description: Recommend articles using NLP-based semantic similarity rather than just keyword matching.

Advanced Features:

  • Word2Vec embeddings for semantic understanding
  • Abstract summarization
  • Topic modeling with LDA
  • Reading time estimation
  • Article difficulty scoring
  • Related concept mapping

Tech Stack: HTML, CSS, JavaScript, PHP, MySQL, Python microservice (optional)

Algorithm: Word2Vec + Cosine Similarity


Project 22: Personalized News Aggregator with Sentiment Analysis

Description: Aggregate news from multiple sources and recommend based on sentiment preference and topic affinity.

Advanced Features:

  • Sentiment analysis on articles
  • Source credibility scoring
  • Bias detection
  • Trending topic identification
  • Personalized digest emails
  • Click-through rate optimization

Tech Stack: HTML, CSS, JavaScript, PHP, MySQL, TextBlob integration

Algorithm: Sentiment-weighted TF-IDF


Project 23: Recipe Recommender with Nutritional Analysis

Description: Suggest recipes based on nutritional goals, allergies, and past cooking behavior.

Advanced Features:

  • Nutritional breakdown calculator
  • Allergy detection and filtering
  • Cooking time prediction
  • Ingredient substitution suggestions
  • Meal planning calendar
  • Grocery list generator

Tech Stack: HTML, CSS, JavaScript, PHP, MySQL, Nutritionix API

Algorithm: Multi-attribute utility theory


Project 24: Music Genre Classifier and Recommender

Description: Analyze audio features (via metadata) to classify and recommend similar music.

Advanced Features:

  • Genre classification
  • Mood detection (happy, sad, energetic)
  • Tempo and key matching
  • Artist similarity network
  • Playlist intelligence
  • Concert recommendations

Tech Stack: HTML, CSS, JavaScript, PHP, MySQL, Spotify API

Algorithm: KNN with audio feature vectors


Project 25: E-commerce Visual Similarity Recommender

Description: Find visually similar products based on image attributes and descriptions.

Advanced Features:

  • Color extraction from images
  • Style classification
  • Price range optimization
  • Complementary product suggestions
  • Virtual try-on integration
  • Social shopping features

Tech Stack: HTML, CSS, JavaScript, PHP, MySQL, ColorThief API

Algorithm: Visual feature extraction + collaborative filtering


Project 26: Academic Paper Citation Recommender

Description: Recommend relevant papers based on citation networks and abstract similarity.

Advanced Features:

  • Citation graph analysis
  • Author influence scoring
  • Journal impact factor consideration
  • Research trend detection
  • Collaboration suggestions
  • Conference recommendations

Tech Stack: HTML, CSS, JavaScript, PHP, MySQL, Crossref API

Algorithm: PageRank + Content similarity


Project 27: Personalized Fitness Plan Generator

Description: Generate dynamic workout plans based on progress, recovery, and goals.

Advanced Features:

  • Exercise progression tracking
  • Recovery time optimization
  • Injury prevention rules
  • Nutrition integration
  • Performance analytics
  • Social challenges

Tech Stack: HTML, CSS, JavaScript, PHP, MySQL, Chart.js

Algorithm: Reinforcement learning with rules


Project 28: Movie Recommender with Emotion Recognition

Description: Recommend movies based on emotional response patterns and scene analysis.

Advanced Features:

  • Emotion tagging per movie
  • Mood-based recommendations
  • Scene intensity analysis
  • Watch party suggestions
  • Critic vs audience balance
  • Award season tracking

Tech Stack: HTML, CSS, JavaScript, PHP, MySQL, TMDB API

Algorithm: Emotional vector matching


Project 29: Job Skill Gap Analyzer

Description: Analyze resumes against job descriptions and recommend learning paths.

Advanced Features:

  • Skill extraction from resumes
  • Industry trend analysis
  • Salary benchmarking
  • Course recommendations
  • Interview preparation
  • Career path visualization

Tech Stack: HTML, CSS, JavaScript, PHP, MySQL, NLP tools

Algorithm: Skill vector comparison


Project 30: Travel Itinerary Optimizer

Description: Create personalized travel plans based on interests, budget, and time constraints.

Advanced Features:

  • POI clustering
  • Route optimization
  • Weather consideration
  • Local event integration
  • Budget tracking
  • Real-time updates

Tech Stack: HTML, CSS, JavaScript, PHP, MySQL, Google Maps API

Algorithm: Genetic algorithm for optimization


Project 31: Book Recommendation with Reading Level Adaptation

Description: Suggest books matching reading level and progressive difficulty.

Advanced Features:

  • Reading level analysis
  • Vocabulary complexity scoring
  • Series completion tracking
  • Author exploration
  • Book club features
  • Reading challenges

Tech Stack: HTML, CSS, JavaScript, PHP, MySQL, Google Books API

Algorithm: Adaptive content filtering


Project 32: Podcast Episode Recommender with Transcript Analysis

Description: Analyze podcast transcripts to recommend episodes by topic depth and style.

Advanced Features:

  • Transcript keyword extraction
  • Speaker identification
  • Topic clustering
  • Episode length optimization
  • Listener engagement prediction
  • Cross-podcast recommendations

Tech Stack: HTML, CSS, JavaScript, PHP, MySQL, Speech-to-text API

Algorithm: BERT embeddings for text


Project 33: Real Estate Property Matcher

Description: Match properties to buyers based on lifestyle preferences and financial capability.

Advanced Features:

  • Neighborhood analysis
  • School district scoring
  • Commute time calculation
  • Investment potential
  • Virtual tour integration
  • Mortgage calculator

Tech Stack: HTML, CSS, JavaScript, PHP, MySQL, Zillow API

Algorithm: Weighted scoring with constraints


Project 34: Wine and Food Pairing Expert

Description: Suggest perfect wine and food pairings based on flavor profiles.

Advanced Features:

  • Flavor wheel integration
  • Regional pairing rules
  • Price optimization
  • Occasion-based suggestions
  • Aging potential
  • User taste evolution tracking

Tech Stack: HTML, CSS, JavaScript, PHP, MySQL

Algorithm: Rule-based expert system


Project 35: YouTube Channel Recommender

Description: Recommend YouTube channels based on content style, upload frequency, and viewer engagement.

Advanced Features:

  • Channel categorization
  • Upload schedule analysis
  • Engagement rate scoring
  • Similar channel networks
  • Content freshness tracking
  • Viewer loyalty metrics

Tech Stack: HTML, CSS, JavaScript, PHP, MySQL, YouTube API

Algorithm: Multi-criteria decision analysis


Project 36: Educational Course Path Generator

Description: Create personalized learning paths through course prerequisites and skill trees.

Advanced Features:

  • Prerequisite mapping
  • Learning style adaptation
  • Progress tracking
  • Certification recommendations
  • Peer learning groups
  • Project suggestions

Tech Stack: HTML, CSS, JavaScript, PHP, MySQL, Graph database

Algorithm: Graph traversal + content similarity


Project 37: Fashion Style Evolution Tracker

Description: Track style evolution and suggest next wardrobe additions.

Advanced Features:

  • Style consistency scoring
  • Trend alignment
  • Color palette analysis
  • Occasion coverage
  • Sustainability scoring
  • Virtual wardrobe management

Tech Stack: HTML, CSS, JavaScript, PHP, MySQL

Algorithm: Temporal pattern matching


Project 38: Meditation and Mindfulness Recommender

Description: Recommend meditation sessions based on mood, time available, and experience level.

Advanced Features:

  • Mood tracking
  • Session effectiveness scoring
  • Voice preference learning
  • Background sound optimization
  • Progress milestones
  • Stress pattern detection

Tech Stack: HTML, CSS, JavaScript, PHP, MySQL

Algorithm: Contextual bandits


Project 39: Crypto Investment Assistant

Description: Recommend cryptocurrency investments based on risk profile and market analysis.

Advanced Features:

  • Risk tolerance assessment
  • Portfolio diversification
  • Market sentiment analysis
  • Technical indicators
  • News impact scoring
  • Tax optimization

Tech Stack: HTML, CSS, JavaScript, PHP, MySQL, Crypto APIs

Algorithm: Multi-factor scoring model


Project 40: Personalized Language Learning Path

Description: Create adaptive language learning paths based on proficiency and learning speed.

Advanced Features:

  • Vocabulary difficulty progression
  • Grammar concept mapping
  • Pronunciation analysis
  • Cultural context integration
  • Spaced repetition system
  • Conversation practice matching

Tech Stack: HTML, CSS, JavaScript, PHP, MySQL

Algorithm: Adaptive mastery learning


Advanced Implementation Architecture

Enhanced Database Schema

-- Advanced schema with more sophisticated features
CREATE DATABASE advanced_content_recommender;
-- Users with detailed profiles
CREATE TABLE users (
id INT PRIMARY KEY AUTO_INCREMENT,
username VARCHAR(50) UNIQUE,
email VARCHAR(100) UNIQUE,
password_hash VARCHAR(255),
full_name VARCHAR(100),
date_of_birth DATE,
gender ENUM('M', 'F', 'Other'),
location VARCHAR(100),
created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
last_active TIMESTAMP,
preference_vector JSON, -- Store user embedding
active BOOLEAN DEFAULT TRUE
);
-- Items with rich metadata
CREATE TABLE items (
id INT PRIMARY KEY AUTO_INCREMENT,
title VARCHAR(200),
description TEXT,
content TEXT, -- Full content for text analysis
category_id INT,
subcategory VARCHAR(100),
tags JSON, -- Array of tags
metadata JSON, -- Flexible metadata storage
embedding TEXT, -- Vector embedding (stored as JSON string)
popularity_score FLOAT DEFAULT 0,
quality_score FLOAT DEFAULT 0,
created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
updated_at TIMESTAMP,
status ENUM('draft', 'published', 'archived') DEFAULT 'published',
FOREIGN KEY (category_id) REFERENCES categories(id)
);
-- Categories hierarchy
CREATE TABLE categories (
id INT PRIMARY KEY AUTO_INCREMENT,
name VARCHAR(100),
parent_id INT,
level INT,
path VARCHAR(255),
FOREIGN KEY (parent_id) REFERENCES categories(id)
);
-- Item attributes with weights
CREATE TABLE item_attributes (
id INT PRIMARY KEY AUTO_INCREMENT,
item_id INT,
attribute_type VARCHAR(50),
attribute_name VARCHAR(100),
attribute_value TEXT,
weight FLOAT DEFAULT 1.0,
confidence FLOAT DEFAULT 1.0,
FOREIGN KEY (item_id) REFERENCES items(id),
INDEX idx_item_attributes (item_id, attribute_type)
);
-- User interactions with context
CREATE TABLE user_interactions (
id INT PRIMARY KEY AUTO_INCREMENT,
user_id INT,
item_id INT,
interaction_type ENUM('view', 'click', 'like', 'share', 'purchase', 'rate', 'comment'),
rating INT CHECK (rating >= 1 AND rating <= 5),
duration INT, -- Time spent in seconds
context JSON, -- Device, time, location etc.
session_id VARCHAR(100),
created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
FOREIGN KEY (user_id) REFERENCES users(id),
FOREIGN KEY (item_id) REFERENCES items(id),
INDEX idx_user_interactions (user_id, item_id, interaction_type)
);
-- User feedback for continuous learning
CREATE TABLE user_feedback (
id INT PRIMARY KEY AUTO_INCREMENT,
user_id INT,
recommendation_id INT,
feedback_type ENUM('relevant', 'not_relevant', 'already_seen', 'not_interested'),
feedback_text TEXT,
created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
FOREIGN KEY (user_id) REFERENCES users(id)
);
-- User segments for targeted recommendations
CREATE TABLE user_segments (
id INT PRIMARY KEY AUTO_INCREMENT,
segment_name VARCHAR(100),
segment_criteria JSON,
user_count INT,
created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
updated_at TIMESTAMP
);
-- User segment membership
CREATE TABLE user_segment_members (
user_id INT,
segment_id INT,
confidence FLOAT,
assigned_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
PRIMARY KEY (user_id, segment_id),
FOREIGN KEY (user_id) REFERENCES users(id),
FOREIGN KEY (segment_id) REFERENCES user_segments(id)
);
-- Pre-computed similarity matrix for performance
CREATE TABLE item_similarity (
item_id_1 INT,
item_id_2 INT,
similarity_score FLOAT,
method VARCHAR(50), -- 'cosine', 'jaccard', 'euclidean'
computed_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
PRIMARY KEY (item_id_1, item_id_2),
FOREIGN KEY (item_id_1) REFERENCES items(id),
FOREIGN KEY (item_id_2) REFERENCES items(id),
INDEX idx_similarity (similarity_score)
);
-- Real-time user sessions
CREATE TABLE user_sessions (
session_id VARCHAR(100) PRIMARY KEY,
user_id INT,
start_time TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
end_time TIMESTAMP,
device_info JSON,
location_info JSON,
FOREIGN KEY (user_id) REFERENCES users(id)
);
-- A/B testing framework
CREATE TABLE ab_tests (
id INT PRIMARY KEY AUTO_INCREMENT,
test_name VARCHAR(100),
test_description TEXT,
algorithm_a VARCHAR(100),
algorithm_b VARCHAR(100),
start_date DATETIME,
end_date DATETIME,
status ENUM('active', 'paused', 'completed')
);
-- Test assignments
CREATE TABLE ab_test_assignments (
id INT PRIMARY KEY AUTO_INCREMENT,
test_id INT,
user_id INT,
variant CHAR(1), -- 'A' or 'B'
assigned_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
FOREIGN KEY (test_id) REFERENCES ab_tests(id),
FOREIGN KEY (user_id) REFERENCES users(id)
);

Advanced PHP Backend with Machine Learning Integration

<?php
// AdvancedRecommender.php
class AdvancedRecommender {
private $db;
private $cache;
private $logger;
public function __construct() {
$this->db = new Database();
$this->cache = new RedisCache(); // Optional caching layer
$this->logger = new Logger();
}
/**
* Hybrid recommendation combining multiple algorithms
*/
public function getHybridRecommendations($userId, $limit = 20, $context = []) {
$startTime = microtime(true);
// Check cache first
$cacheKey = "recommendations:{$userId}:" . md5(json_encode($context));
$cached = $this->cache->get($cacheKey);
if ($cached) {
$this->logger->log("Cache hit for user {$userId}");
return json_decode($cached, true);
}
// Get multiple recommendation sources
$contentBased = $this->getContentBasedRecs($userId, $limit * 2);
$collaborative = $this->getCollaborativeRecs($userId, $limit * 2);
$popularityBased = $this->getPopularityRecs($limit);
$contextual = $this->getContextualRecs($userId, $context, $limit);
// Merge and rank using ensemble method
$recommendations = $this->ensembleRanking([
$contentBased,
$collaborative,
$popularityBased,
$contextual
], $userId, $context);
// Apply diversity boosting
$recommendations = $this->applyDiversity($recommendations, $userId);
// Filter already seen items
$recommendations = $this->filterSeenItems($userId, $recommendations);
// Limit results
$recommendations = array_slice($recommendations, 0, $limit);
// Cache results for 1 hour
$this->cache->set($cacheKey, json_encode($recommendations), 3600);
$executionTime = microtime(true) - $startTime;
$this->logger->log("Generated recommendations for user {$userId} in {$executionTime}s");
return $recommendations;
}
/**
* Content-based recommendations with TF-IDF and embeddings
*/
private function getContentBasedRecs($userId, $limit) {
// Get user profile vector
$userVector = $this->getUserProfileVector($userId);
if (empty($userVector)) {
return [];
}
// Get all items with their vectors
$items = $this->getAllItemVectors();
$scores = [];
foreach ($items as $item) {
$similarity = $this->cosineSimilarity($userVector, $item['vector']);
if ($similarity > 0.3) { // Threshold
$scores[] = [
'item_id' => $item['id'],
'score' => $similarity,
'source' => 'content'
];
}
}
// Sort by score
usort($scores, function($a, $b) {
return $b['score'] <=> $a['score'];
});
return array_slice($scores, 0, $limit);
}
/**
* Collaborative filtering using item-item similarity
*/
private function getCollaborativeRecs($userId, $limit) {
// Get user's highly rated items
$ratedItems = $this->getUserTopItems($userId, 10);
if (empty($ratedItems)) {
return [];
}
$scores = [];
foreach ($ratedItems as $ratedItem) {
// Find similar items
$similarItems = $this->getSimilarItems($ratedItem['item_id'], 20);
foreach ($similarItems as $similarItem) {
$itemId = $similarItem['item_id'];
if (!isset($scores[$itemId])) {
$scores[$itemId] = 0;
}
// Weight by user's rating and item similarity
$scores[$itemId] += $ratedItem['rating'] * $similarItem['similarity'];
}
}
// Normalize scores
$result = [];
foreach ($scores as $itemId => $score) {
$result[] = [
'item_id' => $itemId,
'score' => $score / max($scores),
'source' => 'collaborative'
];
}
// Sort and return
usort($result, function($a, $b) {
return $b['score'] <=> $a['score'];
});
return array_slice($result, 0, $limit);
}
/**
* Context-aware recommendations
*/
private function getContextualRecs($userId, $context, $limit) {
$timeOfDay = date('H');
$dayOfWeek = date('w');
$season = $this->getCurrentSeason();
// Time-based boosting
$timeBoost = [];
if ($timeOfDay < 12) {
$timeBoost['morning'] = 1.2;
$timeBoost['evening'] = 0.8;
} elseif ($timeOfDay < 18) {
$timeBoost['afternoon'] = 1.2;
$timeBoost['night'] = 0.8;
} else {
$timeBoost['evening'] = 1.3;
$timeBoost['morning'] = 0.7;
}
// Weekend boost
if ($dayOfWeek == 0 || $dayOfWeek == 6) {
$timeBoost['weekend'] = 1.3;
}
// Get items with contextual relevance
$query = "SELECT i.*, 
CASE 
WHEN ? = 1 AND i.metadata->'$.suitableForMorning' THEN 1.2
WHEN ? = 2 AND i.metadata->'$.suitableForAfternoon' THEN 1.2
WHEN ? = 3 AND i.metadata->'$.suitableForEvening' THEN 1.3
ELSE 1.0
END as context_score
FROM items i
WHERE i.status = 'published'
ORDER BY context_score DESC, i.popularity_score DESC
LIMIT ?";
$timePeriod = $this->getTimePeriod($timeOfDay);
$stmt = $this->db->connection->prepare($query);
$stmt->bind_param("iiii", $timePeriod, $timePeriod, $timePeriod, $limit * 2);
$stmt->execute();
$result = $stmt->get_result();
$recommendations = [];
while ($row = $result->fetch_assoc()) {
$recommendations[] = [
'item_id' => $row['id'],
'score' => $row['context_score'],
'source' => 'contextual'
];
}
return $recommendations;
}
/**
* Ensemble ranking combining multiple recommendation sources
*/
private function ensembleRanking($recommendationSets, $userId, $context) {
$combined = [];
$weights = $this->getSourceWeights($userId, $context);
// Merge all recommendations with weighted scores
foreach ($recommendationSets as $sourceIndex => $recommendations) {
$weight = $weights[$sourceIndex];
foreach ($recommendations as $rec) {
$itemId = $rec['item_id'];
if (!isset($combined[$itemId])) {
$combined[$itemId] = [
'item_id' => $itemId,
'score' => 0,
'sources' => []
];
}
$combined[$itemId]['score'] += $rec['score'] * $weight;
$combined[$itemId]['sources'][] = $rec['source'];
}
}
// Normalize scores
$maxScore = max(array_column($combined, 'score'));
foreach ($combined as &$rec) {
$rec['score'] = $rec['score'] / $maxScore;
}
// Sort by score
usort($combined, function($a, $b) {
return $b['score'] <=> $a['score'];
});
return $combined;
}
/**
* Apply diversity to avoid similar recommendations
*/
private function applyDiversity($recommendations, $userId) {
if (empty($recommendations)) {
return $recommendations;
}
$diverse = [];
$categories = [];
$maxPerCategory = 3; // Maximum items from same category
foreach ($recommendations as $rec) {
$itemCategory = $this->getItemCategory($rec['item_id']);
if (!isset($categories[$itemCategory])) {
$categories[$itemCategory] = 0;
}
if ($categories[$itemCategory] < $maxPerCategory) {
$diverse[] = $rec;
$categories[$itemCategory]++;
}
}
return $diverse;
}
/**
* Calculate cosine similarity between two vectors
*/
private function cosineSimilarity($vectorA, $vectorB) {
$dotProduct = 0;
$normA = 0;
$normB = 0;
foreach ($vectorA as $key => $valueA) {
if (isset($vectorB[$key])) {
$dotProduct += $valueA * $vectorB[$key];
}
$normA += $valueA * $valueA;
}
foreach ($vectorB as $valueB) {
$normB += $valueB * $valueB;
}
if ($normA == 0 || $normB == 0) {
return 0;
}
return $dotProduct / (sqrt($normA) * sqrt($normB));
}
/**
* Get user profile vector from interactions
*/
private function getUserProfileVector($userId) {
// Check cache
$cacheKey = "user_vector:{$userId}";
$cached = $this->cache->get($cacheKey);
if ($cached) {
return json_decode($cached, true);
}
// Get user's interactions with weights
$query = "SELECT i.embedding, ui.rating, ui.interaction_type
FROM user_interactions ui
JOIN items i ON ui.item_id = i.id
WHERE ui.user_id = ? AND ui.rating >= 3
ORDER BY ui.created_at DESC
LIMIT 50";
$stmt = $this->db->connection->prepare($query);
$stmt->bind_param("i", $userId);
$stmt->execute();
$result = $stmt->get_result();
$userVector = [];
$totalWeight = 0;
while ($row = $result->fetch_assoc()) {
$itemVector = json_decode($row['embedding'], true);
if (!$itemVector) continue;
// Weight based on rating and interaction type
$weight = $row['rating'] / 5;
if ($row['interaction_type'] == 'purchase') {
$weight *= 1.5;
} elseif ($row['interaction_type'] == 'like') {
$weight *= 1.2;
}
foreach ($itemVector as $dimension => $value) {
if (!isset($userVector[$dimension])) {
$userVector[$dimension] = 0;
}
$userVector[$dimension] += $value * $weight;
}
$totalWeight += $weight;
}
// Normalize
if ($totalWeight > 0) {
foreach ($userVector as &$value) {
$value /= $totalWeight;
}
}
// Cache for 1 hour
$this->cache->set($cacheKey, json_encode($userVector), 3600);
return $userVector;
}
/**
* Real-time learning from user feedback
*/
public function processUserFeedback($userId, $itemId, $feedbackType) {
// Store feedback
$query = "INSERT INTO user_feedback (user_id, item_id, feedback_type)
VALUES (?, ?, ?)";
$stmt = $this->db->connection->prepare($query);
$stmt->bind_param("iis", $userId, $itemId, $feedbackType);
$stmt->execute();
// Invalidate caches
$this->cache->delete("recommendations:{$userId}:*");
$this->cache->delete("user_vector:{$userId}");
// Update user profile in real-time
if ($feedbackType == 'relevant') {
$this->boostUserProfile($userId, $itemId);
} elseif ($feedbackType == 'not_relevant') {
$this->penalizeUserProfile($userId, $itemId);
}
// Log for analytics
$this->logger->log("Feedback processed: user={$userId}, item={$itemId}, type={$feedbackType}");
return true;
}
/**
* A/B testing framework
*/
public function runABTest($testId, $userId) {
// Check if user is assigned to this test
$query = "SELECT variant FROM ab_test_assignments 
WHERE test_id = ? AND user_id = ?";
$stmt = $this->db->connection->prepare($query);
$stmt->bind_param("ii", $testId, $userId);
$stmt->execute();
$result = $stmt->get_result();
if ($row = $result->fetch_assoc()) {
return $row['variant'];
}
// Assign new user to test
$variant = (rand(0, 1) == 0) ? 'A' : 'B';
$insertQuery = "INSERT INTO ab_test_assignments (test_id, user_id, variant)
VALUES (?, ?, ?)";
$insertStmt = $this->db->connection->prepare($insertQuery);
$insertStmt->bind_param("iis", $testId, $userId, $variant);
$insertStmt->execute();
return $variant;
}
/**
* Get source weights based on user behavior
*/
private function getSourceWeights($userId, $context) {
// Default weights
$weights = [0.4, 0.3, 0.2, 0.1]; // content, collaborative, popularity, contextual
// Adjust based on user history
$userHistory = $this->getUserInteractionStats($userId);
if ($userHistory['total'] > 100) {
// Power users: more collaborative
$weights = [0.3, 0.5, 0.1, 0.1];
} elseif ($userHistory['total'] < 20) {
// New users: more popularity/content
$weights = [0.5, 0.1, 0.3, 0.1];
}
// Contextual adjustments
if (isset($context['time_sensitive']) && $context['time_sensitive']) {
$weights[3] *= 2; // Boost contextual
// Renormalize
$sum = array_sum($weights);
foreach ($weights as &$w) {
$w /= $sum;
}
}
return $weights;
}
/**
* Get current season
*/
private function getCurrentSeason() {
$month = date('n');
if ($month >= 3 && $month <= 5) return 'spring';
if ($month >= 6 && $month <= 8) return 'summer';
if ($month >= 9 && $month <= 11) return 'fall';
return 'winter';
}
/**
* Get time period (1=morning, 2=afternoon, 3=evening)
*/
private function getTimePeriod($hour) {
if ($hour < 12) return 1;
if ($hour < 18) return 2;
return 3;
}
}

Advanced Frontend with Real-time Updates

<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Advanced Content-Based Recommender</title>
<style>
:root {
--primary-color: #4f46e5;
--secondary-color: #10b981;
--danger-color: #ef4444;
--warning-color: #f59e0b;
--dark-bg: #1f2937;
--light-bg: #f9fafb;
--card-shadow: 0 10px 40px -10px rgba(0,0,0,0.1);
}
* {
margin: 0;
padding: 0;
box-sizing: border-box;
}
body {
font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, sans-serif;
background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
min-height: 100vh;
}
.app-container {
max-width: 1400px;
margin: 0 auto;
padding: 20px;
}
/* Header Styles */
.header {
background: rgba(255,255,255,0.95);
backdrop-filter: blur(10px);
border-radius: 20px;
padding: 20px 30px;
margin-bottom: 30px;
box-shadow: var(--card-shadow);
display: flex;
justify-content: space-between;
align-items: center;
}
.logo {
font-size: 24px;
font-weight: bold;
background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
-webkit-background-clip: text;
-webkit-text-fill-color: transparent;
}
.user-menu {
display: flex;
gap: 20px;
align-items: center;
}
.avatar {
width: 40px;
height: 40px;
border-radius: 50%;
background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
display: flex;
align-items: center;
justify-content: center;
color: white;
font-weight: bold;
}
/* Main Content */
.main-content {
display: grid;
grid-template-columns: 280px 1fr;
gap: 20px;
}
/* Sidebar */
.sidebar {
background: rgba(255,255,255,0.95);
backdrop-filter: blur(10px);
border-radius: 20px;
padding: 20px;
height: fit-content;
}
.profile-section {
text-align: center;
margin-bottom: 30px;
}
.profile-image {
width: 100px;
height: 100px;
border-radius: 50%;
margin: 0 auto 15px;
background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
display: flex;
align-items: center;
justify-content: center;
color: white;
font-size: 40px;
}
.preference-tags {
display: flex;
flex-wrap: wrap;
gap: 8px;
margin: 15px 0;
}
.tag {
background: #e5e7eb;
padding: 5px 10px;
border-radius: 15px;
font-size: 12px;
cursor: pointer;
transition: all 0.3s;
}
.tag.active {
background: var(--primary-color);
color: white;
}
.tag:hover {
background: var(--primary-color);
color: white;
}
/* Recommendations Grid */
.recommendations-section {
background: rgba(255,255,255,0.95);
backdrop-filter: blur(10px);
border-radius: 20px;
padding: 30px;
}
.section-header {
display: flex;
justify-content: space-between;
align-items: center;
margin-bottom: 20px;
}
.section-title {
font-size: 20px;
font-weight: 600;
color: #1f2937;
}
.view-all {
color: var(--primary-color);
text-decoration: none;
font-size: 14px;
}
.items-grid {
display: grid;
grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
gap: 20px;
margin-bottom: 40px;
}
/* Item Card */
.item-card {
background: white;
border-radius: 15px;
overflow: hidden;
box-shadow: 0 4px 6px -1px rgba(0,0,0,0.1);
transition: all 0.3s;
position: relative;
}
.item-card:hover {
transform: translateY(-5px);
box-shadow: 0 20px 25px -5px rgba(0,0,0,0.1);
}
.item-image {
height: 160px;
background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
position: relative;
}
.item-category {
position: absolute;
top: 10px;
right: 10px;
background: rgba(255,255,255,0.9);
padding: 5px 10px;
border-radius: 15px;
font-size: 12px;
font-weight: 500;
}
.item-content {
padding: 15px;
}
.item-title {
font-size: 16px;
font-weight: 600;
margin-bottom: 8px;
color: #1f2937;
}
.item-description {
font-size: 14px;
color: #6b7280;
margin-bottom: 12px;
line-height: 1.4;
}
.item-meta {
display: flex;
justify-content: space-between;
align-items: center;
margin-bottom: 12px;
}
.item-rating {
color: #fbbf24;
font-size: 14px;
}
.item-popularity {
font-size: 12px;
color: #6b7280;
}
.item-actions {
display: flex;
gap: 10px;
}
.btn {
flex: 1;
padding: 8px;
border: none;
border-radius: 8px;
font-size: 13px;
cursor: pointer;
transition: all 0.3s;
}
.btn-primary {
background: var(--primary-color);
color: white;
}
.btn-primary:hover {
background: #4338ca;
}
.btn-secondary {
background: #e5e7eb;
color: #1f2937;
}
.btn-secondary:hover {
background: #d1d5db;
}
.btn-like {
background: #fee2e2;
color: #ef4444;
}
.btn-like:hover {
background: #fecaca;
}
/* Recommendation Badge */
.recommendation-badge {
position: absolute;
top: 10px;
left: 10px;
background: var(--secondary-color);
color: white;
padding: 4px 8px;
border-radius: 12px;
font-size: 11px;
font-weight: 600;
z-index: 10;
}
.recommendation-badge.multiple {
background: var(--warning-color);
}
/* Loading States */
.skeleton {
background: linear-gradient(90deg, #f0f0f0 25%, #e0e0e0 50%, #f0f0f0 75%);
background-size: 200% 100%;
animation: loading 1.5s infinite;
}
@keyframes loading {
0% { background-position: 200% 0; }
100% { background-position: -200% 0; }
}
/* Feedback Modal */
.modal {
display: none;
position: fixed;
top: 0;
left: 0;
right: 0;
bottom: 0;
background: rgba(0,0,0,0.5);
align-items: center;
justify-content: center;
z-index: 1000;
}
.modal.active {
display: flex;
}
.modal-content {
background: white;
border-radius: 20px;
padding: 30px;
max-width: 400px;
width: 90%;
}
.feedback-options {
display: grid;
grid-template-columns: repeat(2, 1fr);
gap: 10px;
margin: 20px 0;
}
.feedback-btn {
padding: 15px;
border: 2px solid #e5e7eb;
border-radius: 10px;
background: white;
cursor: pointer;
transition: all 0.3s;
}
.feedback-btn:hover {
border-color: var(--primary-color);
background: #f5f3ff;
}
/* Responsive */
@media (max-width: 1024px) {
.main-content {
grid-template-columns: 1fr;
}
.sidebar {
order: 2;
}
}
@media (max-width: 768px) {
.items-grid {
grid-template-columns: 1fr;
}
.header {
flex-direction: column;
gap: 15px;
}
}
</style>
</head>
<body>
<div class="app-container">
<!-- Header -->
<header class="header">
<div class="logo">🎯 ContentAI Recommender</div>
<div class="user-menu">
<span>Welcome back, John!</span>
<div class="avatar">JD</div>
</div>
</header>
<!-- Main Content -->
<div class="main-content">
<!-- Sidebar -->
<aside class="sidebar">
<div class="profile-section">
<div class="profile-image">🎯</div>
<h3>Your Preferences</h3>
<p>Based on your interactions</p>
</div>
<div class="preference-tags">
<span class="tag active">Technology</span>
<span class="tag">Science</span>
<span class="tag">Art</span>
<span class="tag">Music</span>
<span class="tag">Travel</span>
<span class="tag">Food</span>
</div>
<div style="margin-top: 20px;">
<h4>Discovery Settings</h4>
<div style="margin: 15px 0;">
<label>Exploration Level</label>
<input type="range" min="0" max="100" value="30" style="width: 100%;">
</div>
<div style="margin: 15px 0;">
<label>Diversity Preference</label>
<input type="range" min="0" max="100" value="50" style="width: 100%;">
</div>
<div style="margin: 15px 0;">
<label>Freshness</label>
<input type="range" min="0" max="100" value="70" style="width: 100%;">
</div>
</div>
<button class="btn btn-primary" style="width: 100%; margin-top: 20px;">
Update Preferences
</button>
</aside>
<!-- Main Recommendations Area -->
<main class="recommendations-section">
<!-- Context Bar -->
<div style="background: #f3f4f6; padding: 15px; border-radius: 10px; margin-bottom: 20px;">
<div style="display: flex; gap: 15px; flex-wrap: wrap;">
<span>📍 Based on your location: New York</span>
<span>⏰ Time: Evening (7:30 PM)</span>
<span>📅 Season: Winter</span>
</div>
</div>
<!-- Hybrid Recommendations -->
<div class="section-header">
<h2 class="section-title">🎯 Hybrid Recommendations</h2>
<a href="#" class="view-all">View All →</a>
</div>
<div id="hybridRecs" class="items-grid">
<!-- Will be populated by JavaScript -->
</div>
<!-- Content-Based Recommendations -->
<div class="section-header">
<h2 class="section-title">📊 Because You Liked...</h2>
<a href="#" class="view-all">View All →</a>
</div>
<div id="contentBasedRecs" class="items-grid">
<!-- Will be populated by JavaScript -->
</div>
<!-- Collaborative Recommendations -->
<div class="section-header">
<h2 class="section-title">👥 People Also Liked</h2>
<a href="#" class="view-all">View All →</a>
</div>
<div id="collaborativeRecs" class="items-grid">
<!-- Will be populated by JavaScript -->
</div>
<!-- Trending Now -->
<div class="section-header">
<h2 class="section-title">🔥 Trending Now</h2>
<a href="#" class="view-all">View All →</a>
</div>
<div id="trendingRecs" class="items-grid">
<!-- Will be populated by JavaScript -->
</div>
</main>
</div>
</div>
<!-- Feedback Modal -->
<div class="modal" id="feedbackModal">
<div class="modal-content">
<h3>How was this recommendation?</h3>
<p>Your feedback helps us improve</p>
<div class="feedback-options">
<button class="feedback-btn" onclick="sendFeedback('relevant')">
👍 Relevant
</button>
<button class="feedback-btn" onclick="sendFeedback('not_relevant')">
👎 Not Relevant
</button>
<button class="feedback-btn" onclick="sendFeedback('already_seen')">
👁️ Already Seen
</button>
<button class="feedback-btn" onclick="sendFeedback('not_interested')">
🚫 Not Interested
</button>
</div>
<button class="btn btn-secondary" style="width: 100%;" onclick="closeModal()">
Close
</button>
</div>
</div>
<script>
// State management
let currentUser = {
id: 1,
name: 'John Doe',
preferences: {
categories: ['Technology', 'Science', 'Art'],
explorationLevel: 30,
diversityPreference: 50,
freshness: 70
}
};
let currentItemForFeedback = null;
let abTestVariant = null;
// Initialize on load
document.addEventListener('DOMContentLoaded', function() {
initializeApp();
loadRecommendations();
setupRealTimeUpdates();
checkABTest();
});
function initializeApp() {
// Load user profile
loadUserProfile();
// Set up event listeners
document.querySelectorAll('.tag').forEach(tag => {
tag.addEventListener('click', togglePreferenceTag);
});
// Setup sliders
setupPreferenceSliders();
}
function loadUserProfile() {
fetch(`/api/user_profile.php?user_id=${currentUser.id}`)
.then(response => response.json())
.then(data => {
if (data.success) {
currentUser.preferences = data.preferences;
updateUIWithPreferences();
}
})
.catch(error => console.error('Error loading profile:', error));
}
function loadRecommendations() {
showLoadingStates();
// Get context
const context = {
timeOfDay: getTimeOfDay(),
dayOfWeek: new Date().getDay(),
location: 'New York', // Would come from geolocation
device: 'desktop'
};
fetch(`/api/hybrid_recommendations.php?user_id=${currentUser.id}&context=${JSON.stringify(context)}`)
.then(response => response.json())
.then(data => {
if (data.success) {
renderRecommendations('hybridRecs', data.hybrid);
renderRecommendations('contentBasedRecs', data.contentBased);
renderRecommendations('collaborativeRecs', data.collaborative);
renderRecommendations('trendingRecs', data.trending);
}
})
.catch(error => {
console.error('Error loading recommendations:', error);
showError('Failed to load recommendations');
})
.finally(() => {
hideLoadingStates();
});
}
function renderRecommendations(containerId, recommendations) {
const container = document.getElementById(containerId);
if (!container) return;
container.innerHTML = '';
recommendations.forEach(item => {
const card = createItemCard(item);
container.appendChild(card);
});
}
function createItemCard(item) {
const card = document.createElement('div');
card.className = 'item-card';
card.dataset.itemId = item.id;
// Add recommendation badge if multiple sources
if (item.sources && item.sources.length > 1) {
const badge = document.createElement('div');
badge.className = 'recommendation-badge multiple';
badge.textContent = `🎯 ${item.sources.length} sources`;
card.appendChild(badge);
} else if (item.source) {
const badge = document.createElement('div');
badge.className = 'recommendation-badge';
badge.textContent = `📊 ${item.source}`;
card.appendChild(badge);
}
const imageDiv = document.createElement('div');
imageDiv.className = 'item-image';
const categorySpan = document.createElement('span');
categorySpan.className = 'item-category';
categorySpan.textContent = item.category || 'General';
imageDiv.appendChild(categorySpan);
card.appendChild(imageDiv);
const contentDiv = document.createElement('div');
contentDiv.className = 'item-content';
contentDiv.innerHTML = `
<h3 class="item-title">${item.title}</h3>
<p class="item-description">${item.description.substring(0, 100)}...</p>
<div class="item-meta">
<span class="item-rating">${'★'.repeat(Math.floor(item.rating || 0))}${'☆'.repeat(5 - Math.floor(item.rating || 0))}</span>
<span class="item-popularity">👥 ${item.popularity || 0} views</span>
</div>
<div class="item-actions">
<button class="btn btn-primary" onclick="interactWithItem(${item.id}, 'view')">View</button>
<button class="btn btn-secondary" onclick="interactWithItem(${item.id}, 'save')">Save</button>
<button class="btn btn-like" onclick="showFeedbackModal(${item.id})">🎯</button>
</div>
`;
card.appendChild(contentDiv);
return card;
}
function interactWithItem(itemId, action) {
fetch('/api/track_interaction.php', {
method: 'POST',
headers: {
'Content-Type': 'application/json',
},
body: JSON.stringify({
user_id: currentUser.id,
item_id: itemId,
interaction_type: action,
context: {
time: new Date().toISOString(),
page: window.location.pathname
}
})
})
.then(response => response.json())
.then(data => {
if (data.success) {
showNotification('Interaction recorded', 'success');
// Real-time update for recommendations
if (action === 'like' || action === 'view') {
refreshRecommendations();
}
}
})
.catch(error => {
console.error('Error tracking interaction:', error);
showNotification('Failed to record interaction', 'error');
});
}
function showFeedbackModal(itemId) {
currentItemForFeedback = itemId;
document.getElementById('feedbackModal').classList.add('active');
}
function closeModal() {
document.getElementById('feedbackModal').classList.remove('active');
currentItemForFeedback = null;
}
function sendFeedback(feedbackType) {
if (!currentItemForFeedback) return;
fetch('/api/feedback.php', {
method: 'POST',
headers: {
'Content-Type': 'application/json',
},
body: JSON.stringify({
user_id: currentUser.id,
item_id: currentItemForFeedback,
feedback_type: feedbackType
})
})
.then(response => response.json())
.then(data => {
if (data.success) {
showNotification('Thank you for your feedback!', 'success');
closeModal();
// Refresh recommendations based on feedback
refreshRecommendations();
}
})
.catch(error => {
console.error('Error sending feedback:', error);
showNotification('Failed to send feedback', 'error');
});
}
function checkABTest() {
fetch(`/api/ab_test.php?user_id=${currentUser.id}&test_id=1`)
.then(response => response.json())
.then(data => {
if (data.success) {
abTestVariant = data.variant;
console.log(`User assigned to variant ${abTestVariant}`);
// Apply variant-specific styling or behavior
document.body.classList.add(`variant-${abTestVariant}`);
}
})
.catch(error => console.error('Error checking A/B test:', error));
}
function refreshRecommendations() {
// Clear cache for this user
fetch(`/api/clear_cache.php?user_id=${currentUser.id}`, { method: 'POST' })
.then(() => {
// Reload recommendations
loadRecommendations();
});
}
function setupRealTimeUpdates() {
// Poll for updates every 30 seconds
setInterval(() => {
if (document.visibilityState === 'visible') {
refreshRecommendations();
}
}, 30000);
// WebSocket for real-time updates (if available)
if (window.WebSocket) {
const ws = new WebSocket('ws://localhost:8080');
ws.onmessage = function(event) {
const data = JSON.parse(event.data);
if (data.type === 'recommendation_update' && data.user_id === currentUser.id) {
refreshRecommendations();
}
};
}
}
function togglePreferenceTag(event) {
const tag = event.target;
tag.classList.toggle('active');
// Update user preferences
const activeTags = Array.from(document.querySelectorAll('.tag.active'))
.map(t => t.textContent);
currentUser.preferences.categories = activeTags;
// Save to server
saveUserPreferences();
}
function setupPreferenceSliders() {
const sliders = document.querySelectorAll('input[type=range]');
sliders.forEach(slider => {
slider.addEventListener('change', function() {
const label = this.previousElementSibling.textContent.toLowerCase();
const value = this.value;
switch(label) {
case 'exploration level':
currentUser.preferences.explorationLevel = value;
break;
case 'diversity preference':
currentUser.preferences.diversityPreference = value;
break;
case 'freshness':
currentUser.preferences.freshness = value;
break;
}
saveUserPreferences();
});
});
}
function saveUserPreferences() {
fetch('/api/update_preferences.php', {
method: 'POST',
headers: {
'Content-Type': 'application/json',
},
body: JSON.stringify(currentUser.preferences)
})
.then(response => response.json())
.then(data => {
if (data.success) {
showNotification('Preferences updated', 'success');
refreshRecommendations();
}
})
.catch(error => {
console.error('Error saving preferences:', error);
showNotification('Failed to save preferences', 'error');
});
}
function getTimeOfDay() {
const hour = new Date().getHours();
if (hour < 12) return 'morning';
if (hour < 18) return 'afternoon';
return 'evening';
}
function showLoadingStates() {
// Add skeleton loading to all recommendation containers
const containers = ['hybridRecs', 'contentBasedRecs', 'collaborativeRecs', 'trendingRecs'];
containers.forEach(containerId => {
const container = document.getElementById(containerId);
if (container) {
container.innerHTML = '';
for (let i = 0; i < 4; i++) {
const skeleton = document.createElement('div');
skeleton.className = 'item-card skeleton';
skeleton.style.height = '280px';
container.appendChild(skeleton);
}
}
});
}
function hideLoadingStates() {
// Remove skeletons - handled by render function
}
function showNotification(message, type) {
// Simple alert for demo - in production, use a toast notification
alert(message);
}
function showError(message) {
showNotification(message, 'error');
}
function updateUIWithPreferences() {
// Update UI based on loaded preferences
document.querySelectorAll('.tag').forEach(tag => {
if (currentUser.preferences.categories.includes(tag.textContent)) {
tag.classList.add('active');
}
});
// Update sliders
const sliders = document.querySelectorAll('input[type=range]');
sliders.forEach(slider => {
const label = slider.previousElementSibling.textContent.toLowerCase();
switch(label) {
case 'exploration level':
slider.value = currentUser.preferences.explorationLevel;
break;
case 'diversity preference':
slider.value = currentUser.preferences.diversityPreference;
break;
case 'freshness':
slider.value = currentUser.preferences.freshness;
break;
}
});
}
</script>
</body>
</html>

API Endpoints for Advanced Features

<?php
// api/hybrid_recommendations.php
require_once '../AdvancedRecommender.php';
$userId = $_GET['user_id'];
$context = json_decode($_GET['context'] ?? '{}', true);
$recommender = new AdvancedRecommender();
$hybrid = $recommender->getHybridRecommendations($userId, 10, $context);
$contentBased = $recommender->getContentBasedRecs($userId, 6);
$collaborative = $recommender->getCollaborativeRecs($userId, 6);
$trending = $recommender->getPopularityRecs(6);
echo json_encode([
'success' => true,
'hybrid' => $hybrid,
'contentBased' => $contentBased,
'collaborative' => $collaborative,
'trending' => $trending
]);
// api/track_interaction.php
require_once '../AdvancedRecommender.php';
$data = json_decode(file_get_contents('php://input'), true);
$recommender = new AdvancedRecommender();
$result = $recommender->trackInteraction(
$data['user_id'],
$data['item_id'],
$data['interaction_type'],
$data['context']
);
echo json_encode(['success' => $result]);
// api/feedback.php
require_once '../AdvancedRecommender.php';
$data = json_decode(file_get_contents('php://input'), true);
$recommender = new AdvancedRecommender();
$result = $recommender->processUserFeedback(
$data['user_id'],
$data['item_id'],
$data['feedback_type']
);
echo json_encode(['success' => $result]);
// api/ab_test.php
require_once '../AdvancedRecommender.php';
$userId = $_GET['user_id'];
$testId = $_GET['test_id'];
$recommender = new AdvancedRecommender();
$variant = $recommender->runABTest($testId, $userId);
echo json_encode([
'success' => true,
'variant' => $variant
]);

Implementation Guide for Each Project

ProjectKey AlgorithmData RequirementsUnique Features
21. Semantic Article RecommenderWord2Vec + CosineArticle text, metadataSemantic understanding
22. News AggregatorSentiment AnalysisNews articles, user clicksSentiment weighting
23. Recipe RecommenderMulti-attribute utilityIngredients, nutrition dataHealth optimization
24. Music ClassifierKNN with audio featuresAudio metadata, genre tagsGenre classification
25. Visual SimilarityColor extractionProduct images, descriptionsVisual matching
26. Paper RecommenderPageRank + ContentCitations, abstractsAcademic focus
27. Fitness PlannerReinforcement learningWorkout data, progressAdaptive planning
28. Movie with EmotionEmotional vectorsMovie tags, user ratingsMood-based
29. Job Skill AnalyzerSkill vector comparisonResumes, job descriptionsCareer focus
30. Travel OptimizerGenetic algorithmPOIs, routes, budgetsRoute optimization
31. Book with Reading LevelAdaptive filteringBook texts, reading levelsProgressive difficulty
32. Podcast TranscriptBERT embeddingsTranscripts, episodesDeep content analysis
33. Real Estate MatcherWeighted scoringProperty data, preferencesLifestyle matching
34. Wine PairingExpert systemWine attributes, foodSommelier rules
35. Channel RecommenderMulti-criteria analysisChannel metadata, engagementYouTube specific
36. Course Path GeneratorGraph traversalCourses, prerequisitesLearning paths
37. Fashion TrackerTemporal matchingWardrobe items, trendsStyle evolution
38. Meditation RecommenderContextual banditsSessions, user moodMindfulness focus
39. Crypto AssistantMulti-factor scoringCrypto data, newsInvestment focus
40. Language LearningAdaptive masteryLessons, progressSpaced repetition

Performance Optimization Tips

  1. Caching Strategy
  • Cache user profiles for 1 hour
  • Cache item similarity matrices for 24 hours
  • Cache recommendation results for 30 minutes
  • Use Redis/Memcached for faster access
  1. Database Optimization
  • Index frequently queried columns
  • Use JSON columns for flexible attributes
  • Partition large tables by date
  • Implement read replicas for scaling
  1. Algorithm Optimization
  • Pre-compute item vectors
  • Use approximate nearest neighbor for large datasets
  • Implement batch processing for offline computation
  • Use incremental updates for user profiles
  1. Frontend Optimization
  • Lazy load images
  • Implement infinite scroll
  • Use service workers for offline capability
  • Optimize bundle size with code splitting

This comprehensive guide provides everything needed to build 40 different content-based recommendation systems, from basic to advanced implementations. Each project can be customized based on specific requirements and scaled according to user base size.

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