Question

我有一个C＃的对象列表，我需要进行透视和转换。但我不确定如何获得理想的结果。下面的代码讨论了结构，数据和期望的结果。我知道，我需要先对数据进行分组，然后再进行转移。但我很困惑如何实现它。

class Program
{
    static void Main(string[] args)
    {
        List<Rev> revList = new List<Rev>();
        Rev r = new Rev { Id = 1, Name = "One", Rank = 1, Region = "Global", Revenue = 600 }; revList.Add(r);
        r = new Rev { Id = 1, Name = "One", Rank = 1, Region = "USA", Revenue = 100 }; revList.Add(r);
        r = new Rev { Id = 1, Name = "One", Rank = 1, Region = "Euro", Revenue = 200 }; revList.Add(r);
        r = new Rev { Id = 1, Name = "One", Rank = 1, Region = "APAC", Revenue = 300 }; revList.Add(r);

        r = new Rev { Id = 2, Name = "Two", Rank = 2, Region = "Global", Revenue = 500 }; revList.Add(r);
        r = new Rev { Id = 2, Name = "Two", Rank = 2, Region = "USA", Revenue = 100 }; revList.Add(r);
        r = new Rev { Id = 2, Name = "Two", Rank = 3, Region = "APAC", Revenue = 400 }; revList.Add(r);

        r = new Rev { Id = 3, Name = "Three", Rank = 2, Region = "Global", Revenue = 300 }; revList.Add(r);
        r = new Rev { Id = 3, Name = "Three", Rank = 2, Region = "USA", Revenue = 100 }; revList.Add(r);
        r = new Rev { Id = 3, Name = "Three", Rank = 3, Region = "Euro", Revenue = 200 }; revList.Add(r);

        //Should result in THIS IS THE HARD CODED RESULT WHICH TRANFORM FUNCTION SHOULD GENERATE
        List<RevExtended> resultList = new List<RevExtended>();
        RevExtended res = new RevExtended{Name = "One", Id = 1, APACRevenue = 300, ApacRank = 1, EuroRank = 1, EurpRevenue = 200, GlobalRank = 1, GlobalRevenue = 600, USARank = 1, USARevenue = 100};
        res = new RevExtended { Name = "Two", Id = 2, APACRevenue = 400, ApacRank = 3, GlobalRank = 2, GlobalRevenue = 500, USARank = 2, USARevenue = 100 };
        res = new RevExtended { Name = "Three", Id = 3, EuroRank = 3, EurpRevenue = 200, GlobalRank = 2, GlobalRevenue = 300, USARank = 2, USARevenue = 100 };
    }

    public List<RevExtended> Transform(List<Rev> revList)
    {
        List<RevExtended> resultList = new List<RevExtended>();

        var query = from rev in revList
                    group rev by rev.Id into revGroup


        return resultList;
    }
}

public class Rev
{
    public string Name { get; set; }
    public int Id { get; set; }
    public int? Revenue { get; set; }
    public int? Rank { get; set; }
    public string Region { get; set; }
}

public class RevExtended
{
    public string Name { get; set; }
    public int Id { get; set; }

    public int? GlobalRevenue { get; set; }
    public int? GlobalRank { get; set; }

    public int? USARevenue { get; set; }
    public int? USARank { get; set; }

    public int? EurpRevenue { get; set; }
    public int? EuroRank { get; set; }

    public int? APACRevenue { get; set; }
    public int? ApacRank { get; set; }
}

Answer 1

以下是您可以采取的一种方法：

var pivoted =
    from d in data
    group d by new { d.Id, d.Name } into region
    let g = region.SingleOrDefault(d => d.Region == "Global") ?? new Rev()
    let u = region.SingleOrDefault(d => d.Region == "USA") ?? new Rev()
    let e = region.SingleOrDefault(d => d.Region == "Euro") ?? new Rev()
    let a = region.SingleOrDefault(d => d.Region == "APAC") ?? new Rev()
    select new RevExtended
    {
        Id = region.Key.Id,
        Name = region.Key.Name,
        GlobalRevenue = g.Revenue,
        GlobalRank = g.Rank,
        UsaRevenue = u.Revenue,
        UsaRank = u.Rank,
        EuroRevenue = e.Revenue,
        EuroRank = e.Rank,
        ApacRevenue = a.Revenue,
        ApacRank = a.Rank,
    };

如果在没有区域的情况下需要null值，则需要更改模型以便能够支持它们。

public class RevExtended
{
    public int Id { get; set; }
    public string Name { get; set; }

    public int? GlobalRank { get; set; }
    public int? GlobalRevenue { get; set; }

    public int? UsaRank { get; set; }
    public int? UsaRevenue { get; set; }

    public int? EuroRank { get; set; }
    public int? EuroRevenue { get; set; }

    public int? ApacRank { get; set; }
    public int? ApacRevenue { get; set; }
}

var pivoted =
    from d in data
    group d by new { d.Id, d.Name } into region
    let g = region.SingleOrDefault(d => d.Region == "Global")
    let u = region.SingleOrDefault(d => d.Region == "USA")
    let e = region.SingleOrDefault(d => d.Region == "Euro")
    let a = region.SingleOrDefault(d => d.Region == "APAC")
    select new RevExtended
    {
        Id = region.Key.Id,
        Name = region.Key.Name,
        GlobalRevenue = g?.Revenue,
        GlobalRank = g?.Rank,
        UsaRevenue = u?.Revenue,
        UsaRank = u?.Rank,
        EuroRevenue = e?.Revenue,
        EuroRank = e?.Rank,
        ApacRevenue = a?.Revenue,
        ApacRank = a?.Rank,
    };

Answer 2

当您不使用C＃6.0

时

var pivoted =
    from x in revList.ToLookup(d => new { d.Id, d.Name })
    let g = x.SingleOrDefault(d => d.Region == "Global") ?? new Rev()
    let u = x.SingleOrDefault(d => d.Region == "USA") ?? new Rev()
    let e = x.SingleOrDefault(d => d.Region == "Euro") ?? new Rev()
    let a = x.SingleOrDefault(d => d.Region == "APAC") ?? new Rev()
    select new RevExtended
    {
        Id = x.Key.Id,
        Name = x.Key.Name,
        GlobalRevenue = g.Revenue == null ? null : g.Revenue,
        GlobalRank = g.Rank == null ? null : g.Rank,
        USARevenue = u.Revenue == null ? null : u.Revenue,
        USARank = u.Rank == null ? null : u.Rank,
        EuroRevenue = e.Revenue == null ? null: e.Revenue,
        EuroRank = e.Rank == null ? null : e.Rank,
        ApacRevenue = a.Revenue == null ? null : a.Revenue,
        ApacRank = a.Rank == null ? null : a.Rank,
    };

Answer 3

@OpenStack，根据接受答案的最后部分，您有一个针对6.0之前的C＃用户的答案。你的例子并不完全正确。有两个问题：

您的示例将始终具有Rev对象，因此对象引用永远不会为空。
如果您确实允许空值（按预期），则赋值逻辑不会保护您免受空值的影响。

这里等同于早于6.0的C＃版本的接受答案：

var pivoted =
    from x in revList.ToLookup(d => new { d.Id, d.Name })
    let g = x.SingleOrDefault(d => d.Region == "Global") 
    let u = x.SingleOrDefault(d => d.Region == "USA")
    let e = x.SingleOrDefault(d => d.Region == "Euro")
    let a = x.SingleOrDefault(d => d.Region == "APAC")
    select new RevExtended
    {
        Id = x.Key.Id,
        Name = x.Key.Name,
        GlobalRevenue = g == null ? null : g.Revenue,
        GlobalRank = g == null ? null : g.Rank,
        USARevenue = u == null ? null : u.Revenue,
        USARank = u == null ? null : u.Rank,
        EuroRevenue = e == null ? null: e.Revenue,
        EuroRank = e == null ? null : e.Rank,
        ApacRevenue = a == null ? null : a.Revenue,
        ApacRank = a == null ? null : a.Rank,
    };

如果您同意，您可以更新您的答案以使其正确（如果您愿意，可以复制并粘贴我的答案），我将删除此答案。

在C＃中旋转多个列

3 个答案: