public List <Product> KnnRecommandation()
{
List <Product> products = _context.Products.ToList();
List <Product> recommendedProducts = new List <Product>();
List <Product> purchaseProducts = new List <Product>();
if (User.Identity.IsAuthenticated)
{
int customerId = int.Parse(User.Claims.FirstOrDefault(claim => claim.Type == ClaimTypes.Sid).Value);
var recentOrders = _context.Orders.Where(order => order.CustomerID == customerId).Include(o => o.customer).Include(o => o.PurchaseProducts).ThenInclude(p => p.Product).AsQueryable();
if (recentOrders.ToList().Count == 0)
{
return(recommendedProducts);
}
if (recentOrders.ToList().Count > 5)
{
recentOrders = recentOrders.OrderByDescending(a => a.OrderDate).Take(5);
}
foreach (var order in recentOrders)
{
foreach (var purchase in order.PurchaseProducts)
{
purchaseProducts.Add(purchase.Product);
}
}
int count = purchaseProducts.Count();
int[,] vectors = new int[count, 3];
for (int i = 0; i < count; i++)
{
vectors[i, 0] = (int)purchaseProducts[i].Title;
}
for (int i = 0; i < count; i++)
{
vectors[i, 1] = (int)purchaseProducts[i].Color;
}
for (int i = 0; i < count; i++)
{
vectors[i, 2] = (int)purchaseProducts[i].price;
}
products.RemoveAll(p => purchaseProducts.Where(p2 => p.ID == p2.ID).ToList().Count != 0);//??????
List <int> recommanded = Knn.Distance(vectors, products);
foreach (int id in recommanded)
{
recommendedProducts.Add(products.Where(a => a.ID == id).Single());
}
}
return(recommendedProducts);
}