public List <CustomProductsDTO> GetRecommendedProducts(Dictionary <int, int> userRatings)
{
int[] userIds = db.Database.SqlQuery <int>(@"select distinct user_id_id from user_rates ur
inner join inventory i on ur.product_id_id = i.product_id_id and i.in_stock > 0").ToArray();
List <user_rates> userRates = db.user_rates.Where(x => userIds.Contains(x.user_id_id)).ToList();
Dictionary <int, double> uCoeficient = new Dictionary <int, double>();
double avgAURRating = userRatings.Sum(x => x.Value) / userRatings.Count;
if (avgAURRating % 1 == 0)
{
avgAURRating += 0.00001;
}
foreach (int userID in userIds)
{
double divisible = 0;
double divisorAUR = 0;
double divisorUR = 0;
double coeficient = 0;
List <user_rates> uRates = userRates.Where(x => x.user_id_id == userID).ToList();
double avgURRating = uRates.Sum(x => x.rate) / uRates.Count;
if (avgURRating % 1 == 0)
{
avgURRating += 0.00001;
}
foreach (int prodID in userRatings.Keys)
{
user_rates rate = uRates.FirstOrDefault(x => x.product_id_id == prodID);
if (rate == null)
{
continue;
}
divisible += (userRatings[prodID] - avgAURRating) * (rate.rate - avgURRating);
divisorAUR += Math.Pow((double)(userRatings[prodID] - avgAURRating), 2);
divisorUR += Math.Pow((double)(rate.rate - avgURRating), 2);
}
coeficient = divisible / (Math.Sqrt(divisorAUR) * Math.Sqrt(divisorUR));
if (Double.IsNaN(coeficient))
{
coeficient = 0;
}
uCoeficient.Add(userID, coeficient);
}
int[] topUsers = uCoeficient.OrderByDescending(x => x.Value).Take(10).Select(x => x.Key).ToArray();
List <user_rates> topUserRates = userRates.Where(x => topUsers.Contains(x.user_id_id)).ToList();
int[] productsArray = topUserRates.Select(x => x.product_id_id).ToArray();
List <inventory> inventory = db.inventory.ToList();
inventory = inventory.Where(y => productsArray.Contains(y.product_id_id) && !userRatings.ContainsKey(y.product_id_id)).ToList();
Dictionary <int, double> recrate = new Dictionary <int, double>();
foreach (inventory inv in inventory)
{
int prodId = inv.product_id_id;
List <user_rates> ratesByProduct = topUserRates.Where(x => x.product_id_id == prodId).ToList();
double totalRateValue = 0;
foreach (user_rates rate in ratesByProduct)
{
totalRateValue += uCoeficient[rate.user_id_id] * rate.rate;
}
recrate.Add(prodId, totalRateValue / ratesByProduct.Count);
}
int[] topProductIds = recrate.OrderByDescending(x => x.Value).Take(10).Select(x => x.Key).ToArray();
List <products> topProducts = db.products.Include("categories").Include("vendors").Include("vendors.regions").Include("vendors.regions.countries").Include("appellation").Where(x => topProductIds.Contains(x.id)).ToList();
List <CustomProductsDTO> result = new List <CustomProductsDTO>();
int currentRank = 1;
foreach (products prod in topProducts)
{
CustomProductsDTO newDTO = new CustomProductsDTO();
newDTO.ProdID = prod.id;
newDTO.ProdName = prod.name;
newDTO.VendorName = prod.vendors.name;
newDTO.CategoryName = prod.categories.name;
newDTO.RegionName = prod.vendors.regions.name;
newDTO.CountryName = prod.vendors.regions.countries.name;
newDTO.PhotoPath = prod.photo_path;
newDTO.Rate = (int)recrate[prod.id];
result.Add(newDTO);
currentRank++;
}
result = result.Where(x => x.Rate > 0).OrderByDescending(x => x.Rate).ToList();
return(result);
}
public List <ProductDetailsDTO> GetRecommendedProductsByProductCategory(int productId)
{
products selectedProduct = db.products.FirstOrDefault(x => x.id == productId);
int[] productIds = db.Database.SqlQuery <int>(@" select distinct ur.product_id_id from user_rates ur
inner join inventory i on ur.product_id_id = i.product_id_id and i.in_stock > 0
inner join products p on p.id = ur.product_id_id
where ur.product_id_id <> '" + productId + "' AND p.category_id_id = '" + selectedProduct.category_id_id + "'").ToArray();
List <user_rates> userRates = db.user_rates.Where(x => productIds.Contains(x.product_id_id)).ToList();
Dictionary <int, double> uCoeficient = new Dictionary <int, double>();
List <user_rates> spRates = db.user_rates.Where(x => x.product_id_id == productId).ToList();
if (spRates.Count == 0)
{
return(null);
}
double avgSPRating = spRates.Sum(x => x.rate) / spRates.Count;
if (avgSPRating % 1 == 0)
{
avgSPRating += 0.00001;
}
foreach (int prodID in productIds)
{
double divisible = 0;
double divisorSP = 0;
double divisorP = 0;
double coeficient = 0;
List <user_rates> pRates = userRates.Where(x => x.product_id_id == prodID).ToList();
double avgPRating = pRates.Sum(x => x.rate) / pRates.Count;
if (avgPRating % 1 == 0)
{
avgPRating += 0.00001;
}
foreach (int userID in pRates.Select(x => x.user_id_id))
{
user_rates rate = pRates.FirstOrDefault(x => x.user_id_id == userID);
user_rates spRate = spRates.FirstOrDefault(x => x.user_id_id == userID);
if (rate == null || spRate == null)
{
continue;
}
divisible += (spRate.rate - avgSPRating) * (rate.rate - avgPRating);
divisorSP += Math.Pow((double)(spRate.rate - avgSPRating), 2);
divisorP += Math.Pow((double)(rate.rate - avgPRating), 2);
}
coeficient = divisible / (Math.Sqrt(divisorSP) * Math.Sqrt(divisorP));
if (Double.IsNaN(coeficient))
{
coeficient = 0;
}
uCoeficient.Add(prodID, coeficient);
}
int[] topProducts = uCoeficient.OrderByDescending(x => x.Value).Take(10).Select(x => x.Key).ToArray();
List <inventory> inventory = db.inventory.ToList();
inventory = inventory.Where(y => topProducts.Contains(y.product_id_id)).ToList();
Dictionary <int, double> recrate = new Dictionary <int, double>();
foreach (inventory inv in inventory)
{
int prodId = inv.product_id_id;
List <user_rates> ratesByProduct = userRates.Where(x => x.product_id_id == prodId).ToList();
double totalRateValue = 0;
foreach (user_rates rate in ratesByProduct)
{
totalRateValue += uCoeficient[rate.product_id_id] * rate.rate;
}
recrate.Add(prodId, totalRateValue / ratesByProduct.Count);
}
int[] topProductIds = recrate.OrderByDescending(x => x.Value).Take(10).Select(x => x.Key).ToArray();
List <products> recommendedProducts = db.products.Include("categories").Include("vendors").Include("vendors.regions").Include("vendors.regions.countries").Include("appellation").Where(x => topProductIds.Contains(x.id)).ToList();
List <ProductDetailsDTO> result = new List <ProductDetailsDTO>();
foreach (products prod in recommendedProducts)
{
ProductDetailsDTO newDTO = new ProductDetailsDTO();
newDTO.ProdID = prod.id;
newDTO.ProdName = prod.name;
newDTO.VendorName = prod.vendors.name;
newDTO.CategoryName = prod.categories.name;
newDTO.RegionName = prod.vendors.regions.name;
newDTO.CountryName = prod.vendors.regions.countries.name;
newDTO.PhotoPath = prod.photo_path;
newDTO.UserAvgRate = (int)recrate[prod.id];
result.Add(newDTO);
}
result = result.Where(x => x.UserAvgRate > 0).OrderByDescending(x => x.UserAvgRate).ToList();
return(result);
}
