public TResult RecommendItem <TResult>(string itemId, IResultBuilderFactory <TResult> resultBuilderFactory)
{
if (itemId == null)
{
throw new ArgumentNullException(nameof(itemId));
}
if (!this.itemMap.ContainsKey(itemId))
{
return(resultBuilderFactory.CreateEmpty());
}
var yi = this.itemFactors.Row(this.itemMap[itemId]);
var yj = Vector <double> .Build.Dense(this.factors);
var resultBuilder = resultBuilderFactory.CreateBuilder(maximumCapacity: this.itemMap.Count);
foreach (var item in this.itemMap)
{
var j = item.Value;
this.itemFactors.Row(j, yj);
resultBuilder.Append(item.Key, yi.DotProduct(yj) / this.ItemNorms[j]);
}
return(resultBuilder.ToResult());
}
public TResult RecommendUser <TResult>(string userId, IResultBuilderFactory <TResult> resultBuilderFactory)
{
if (userId == null)
{
throw new ArgumentNullException(nameof(userId));
}
if (!this.userMap.ContainsKey(userId))
{
return(resultBuilderFactory.CreateEmpty());
}
var xu = this.userFactors.Row(this.userMap[userId]);
var user = new UserFeatures(xu);
return(this.RecommendUser(user, resultBuilderFactory));
}
public TResult RankUsers <TResult>(string userId, List <KeyValuePair <string, UserFeatures> > users, IResultBuilderFactory <TResult> resultBuilderFactory)
{
if (userId == null)
{
throw new ArgumentNullException(nameof(userId));
}
if (users == null)
{
throw new ArgumentNullException(nameof(users));
}
if (!this.userMap.ContainsKey(userId))
{
return(resultBuilderFactory.CreateEmpty());
}
var xu = this.userFactors.Row(this.userMap[userId]);
var user = new UserFeatures(xu);
return(this.RankUsers(user, users, resultBuilderFactory));
}