对集合进行排序并根据特定条件对结果进行排名

Question

说我有以下内容

var searches = new ObservableCollection<Book>();

searches 包含书籍对象

public class Book
{
    public string Title { get; set;}
    public string Desc {get; set;}    
}

我想searches按匹配的字符串排序.首先,它Title根据搜索字符串从一开始的接近程度来检查排名Title.接下来,它检查Desc并根据搜索字符串从描述的开头出现的距离进行排序.

例如,如果我有

第1册
标题:ABC书名
说明:书1的描述

第2册
标题:书名仅
描述:第2 册的描述中有一个ABC

书3
标题:书名ABC
描述:ABC在开头

所以,请说搜索关键字是ABC,我想要searches排序,以便我得到以下内容.结果为包含标题中的搜索字符串的项目提供了更高的优先级.

第1册
标题:ABC书名
说明:书1的描述

书3
标题:书名ABC
描述:ABC在开头

第2册
标题:书名仅
描述:第2 册的描述中有一个ABC

如何使用LINQ实现这一目标？

Answer 1

您可以使用排名功能为每本书定义"分数",然后按分数排序.

即

var searchString = "ABC";
var results = books.Select(b => new { Book = b, Rank = RankBook(b, searchString) })
                   .OrderBy(r => r.Rank)
                   .Select(r => r.Book.Title);

并且排名功能:

private int RankBook(Book b, string searchString)
{
    int rank = 0;
    if (b.Title.Contains(searchString)) rank += 10;

    if (b.Desc.Contains(searchString)) rank += 5;

    return rank;
}

这就是说:在标题= 10点,在desc = 5分中找到,所以你得到最高分的最相关的书.

Answer 2

您可以使用OrderBy和ThenBy

var searches = new ObservableCollection<Book>();

searches.Add(new Book()
{
    Desc = "The description of book 1",
    Title = "ABC Book Title"
});

searches.Add(new Book()
{
    Desc = "Book Title Only",
    Title = "There's an ABC in the description of book 2"
});

searches.Add(new Book()
{
    Desc = "Book Title ABC",
    Title = "ABC is in the beginning"
});

var ordered = new ObservableCollection<Book>(searches.OrderBy(book => book.Title).ThenBy(book => book.Desc.Contains("ABC")));

更新

我已经添加了一个排名系统,希望能帮助您找到您想要的东西.我使用的只是IndexOf来确定条件的位置并将其存储在Book对象的属性中.我的另一个建议是你为你的书创建一个独立的集合(使用继承),这样你就可以根据需要自定义它,而不必在对象本身的上下文之外编写太多代码

public class BookCollection : ObservableCollection<Book> // Notice the Inheritance to ObservableCollection
{
    public void SetCriteria(string search)
    {
        if(string.IsNullOrEmpty(search))
            return;

        foreach (var book in this)
        {
            if(book.Title.Contains(search))
                book.TitleRank = book.Title.IndexOf(search, StringComparison.InvariantCulture);

            if(book.Desc.Contains(search))
                book.DescRank = book.Desc.IndexOf(search, StringComparison.InvariantCulture);
        }

        var collection = new List<Book>(base.Items.OrderBy(book => book.Title)
                                                  .ThenBy(book => book.Desc)
                                                  .ThenBy(book => book.TitleRank)
                                                  .ThenBy(book => book.DescRank));
        Items.Clear();

        collection.ForEach(Add);
        collection.Clear();
    }
}

public class Book
{
    public string Title { get; set; }
    public string Desc { get; set; }
    public int TitleRank { get; internal set; }
    public int DescRank { get; internal set; }
}

现在要使用这个新的集合,你所要做的就是这样称呼它.

var collection = new BookCollection();
collection.Add(new Book { Desc = "Book Title ABC", Title = "ABC is in the beginning" });
// Add your other books here........
collection.SetCriteria("ABC");
// your new collection is now sorted and ready to use, no need to write any extra sorting code here

请记住,如果您需要为排序添加更多条件,则必须在SetCriteria方法中执行此操作.希望这可以帮助.

Answer 3

感谢 @M Patel 和 Stefano 的建议，我得到了以下解决方案

var sorted = searches.Select(tile => new { TileViewModel = tile, Rank = rankResult(tile, text) })
                    .OrderByDescending(r => r.Rank)
                    .Select(r => r.TileViewModel);

SearchResultsTilesVM = new ObservableCollection<TileViewModel>(sorted);

取关键字位置的方法。如果标题中找到匹配项，我会加分。

    private int rankResult(TileViewModel vm, string keyword)
    {
        double rank = 0;

        //Added 100 to give stronger weight when keyword found in title
        int index = vm.Title.IndexOf(keyword, StringComparison.InvariantCultureIgnoreCase);

        if (index >= 0 )
        {
            rank = (double)(vm.Title.Length - index) / (double)vm.Title.Length * 100 + 100;
        }         

        int index2 = vm.Information.IndexOf(keyword, StringComparison.InvariantCultureIgnoreCase);

        if (index2 >= 0)
        {
            rank += (double)(vm.Information.Length - index2) / (double)vm.Information.Length * 100;
        }

        return Convert.ToInt32(rank);
    }