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次のことをうまく実行する方法を作成するのを手伝ってくれる人はいますか?:

一部のユーザーにいくつかの異なるアイテムを評価してもらいます。

ユーザーに良いレコメンデーションを提供するには、好みが似ているユーザーを見つける必要があります。好みが似ている他のユーザーの評価の高い商品をおすすめできるように。

私のデータは、Entity Framework でマップされたデータベースから取得されています。

私は動作しているアルゴリズムを持っていますが、パフォーマンスが悪く、多くのループを実行しています。何か案は？

/ケント

namespace ConsoleApplication1
{
    using System;
    using System.Collections.Generic;

    class Program
    {
        static void Main()
        {
            const int NoOfUsers = 100;
            const int NoOfRatingsPerUser = 100;
            const int NoOfDifferentItems = 100;

            var listOfRatings = new List<Rating>();

            var r = new Random();

            for (int user = 0; user < NoOfUsers; user++)
            {
                for (int ratingsPerUser = 0; ratingsPerUser < NoOfRatingsPerUser; ratingsPerUser++)
                {
                    var rating = new Rating();
                    rating.Score = r.Next(1, 10);
                    rating.ItemId = r.Next(1, NoOfDifferentItems);
                    rating.UserId = user;
                    listOfRatings.RemoveAll(x => x.UserId == user && x.ItemId == rating.ItemId);
                    listOfRatings.Add(rating);
                }
            }
            Console.ReadLine();
        }

        struct Rating
        {
            public int ItemId;

            public int Score;

            public int UserId;
        }
    }
}
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1 に答える 1

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評価アルゴリズムが表示されません。あなたは検索で殺されていました。KeyedCollection はここにぴったりです。

P4 では 62 ミリ秒。1000 (100 ではない);

    public void BuildData()
    {
        System.Diagnostics.Stopwatch stopWatch = new System.Diagnostics.Stopwatch();
        stopWatch.Start();

        RatingKC Ratings = new RatingKC();

        const Int16 NoOfUsers = 1000;
        const Int16 NoOfRatingsPerUser = 1000;
        const Int16 NoOfDifferentItems = 1000;
        Int16 itemID;
        int score;
        Int32 key;
        var r = new Random();

        for (Int16 userID = 0; userID < NoOfUsers; userID++)
        {
            for (int ratingsPerUser = 0; ratingsPerUser < NoOfRatingsPerUser; ratingsPerUser++)
            {
                itemID = (Int16)r.Next(1, NoOfDifferentItems);
                score = r.Next(1, 10);
                key = (userID & 0xffff) + (itemID << 16);
                if (Ratings.Contains(key))
                {
                    Ratings[key].Score = score;
                }
                else
                {
                    Ratings.Add(new Rating(userID, itemID, score));   
                }
            }
        }
        stopWatch.Stop();
        // Get the elapsed time as a TimeSpan value.
        TimeSpan ts = stopWatch.Elapsed;

        // Format and display the TimeSpan value.
        string elapsedTime = String.Format("{0:00}:{1:00}:{2:00}.{3:00}",
            ts.Hours, ts.Minutes, ts.Seconds,
            ts.Milliseconds / 10);
        System.Diagnostics.Debug.WriteLine("Count = " + Ratings.Count.ToString() + " Time = " + elapsedTime);
    }
}
public class RatingKC : KeyedCollection<int, Rating>
{
    // The parameterless constructor of the base class creates a 
    // KeyedCollection with an internal dictionary. For this code 
    // example, no other constructors are exposed.
    //
    public RatingKC() : base() { }

    // This is the only method that absolutely must be overridden,
    // because without it the KeyedCollection cannot extract the
    // keys from the items. The input parameter type is the 
    // second generic type argument, in this case OrderItem, and 
    // the return value type is the first generic type argument,
    // in this case int.
    //
    protected override int GetKeyForItem(Rating item)
    {
        // In this example, the key is the part number.
        return item.Key;
    }
}
public class Rating: Object
{
    public Int16 UserId { get; private set; }
    public Int16 ItemId { get; private set;}
    public int Score { get; set;}
    public Int32 Key { get { return (UserId & 0xffff) + (ItemId << 16); } }
    public override bool Equals(Object obj)
    {
        //Check for null and compare run-time types.
        if (obj == null || !(obj is Rating)) return false;
        Rating item = (Rating)obj;
        return (UserId == item.UserId && ItemId == item.ItemId);
    }
    public override int GetHashCode()
    {
        return Key;
    }

    public Rating(Int16 userId, Int16 itemId, int score)
    { UserId = userId; ItemId = itemId; Score = score; }
    public Rating(Int16 userId, Int16 itemId)
    { UserId = userId; ItemId = itemId; }
}
于 2012-04-29T12:43:58.287 に答える