使用LINQ旋转数据

我试图看看我是否可以使用LINQ来解决我遇到的问题。 我有一个包含Enum（TypeCode）和User对象的项目集合，我需要将其展平以显示在网格中。 这很难解释，所以让我举一个简单的例子。

集合有这样的项目：

TypeCode | User --------------- 1 | Don Smith 1 | Mike Jones 1 | James Ray 2 | Tom Rizzo 2 | Alex Homes 3 | Andy Bates 

我需要输出为：

 1 | 2 | 3 Don Smith | Tom Rizzo | Andy Bates Mike Jones | Alex Homes | James Ray | | 

感谢任何可以帮助我的人！ 我尝试使用foreach这样做，但是我不能这样做，因为我要在foreach中将新项目插入到集合中，从而导致错误。

Answer 1

我并不是说它是一种很好的转向方式 – 但它是一个支点……

  // sample data var data = new[] { new { Foo = 1, Bar = "Don Smith"}, new { Foo = 1, Bar = "Mike Jones"}, new { Foo = 1, Bar = "James Ray"}, new { Foo = 2, Bar = "Tom Rizzo"}, new { Foo = 2, Bar = "Alex Homes"}, new { Foo = 3, Bar = "Andy Bates"}, }; // group into columns, and select the rows per column var grps = from d in data group d by d.Foo into grp select new { Foo = grp.Key, Bars = grp.Select(d2 => d2.Bar).ToArray() }; // find the total number of (data) rows int rows = grps.Max(grp => grp.Bars.Length); // output columns foreach (var grp in grps) { Console.Write(grp.Foo + "\t"); } Console.WriteLine(); // output data for (int i = 0; i < rows; i++) { foreach (var grp in grps) { Console.Write((i < grp.Bars.Length ? grp.Bars[i] : null) + "\t"); } Console.WriteLine(); } 

Answer 2

Marc的答案给出了稀疏矩阵，不能直接泵入Grid。
我试图从Vasu提供的链接扩展代码，如下所示：

 public static Dictionary> Pivot3( this IEnumerable source , Func key1Selector , Func key2Selector , Func, TValue> aggregate) { return source.GroupBy(key1Selector).Select( x => new { X = x.Key, Y = source.GroupBy(key2Selector).Select( z => new { Z = z.Key, V = aggregate(from item in source where key1Selector(item).Equals(x.Key) && key2Selector(item).Equals(z.Key) select item ) } ).ToDictionary(e => eZ, o => oV) } ).ToDictionary(e => eX, o => oY); } internal class Employee { public string Name { get; set; } public string Department { get; set; } public string Function { get; set; } public decimal Salary { get; set; } } public void TestLinqExtenions() { var l = new List() { new Employee() { Name = "Fons", Department = "R&D", Function = "Trainer", Salary = 2000 }, new Employee() { Name = "Jim", Department = "R&D", Function = "Trainer", Salary = 3000 }, new Employee() { Name = "Ellen", Department = "Dev", Function = "Developer", Salary = 4000 }, new Employee() { Name = "Mike", Department = "Dev", Function = "Consultant", Salary = 5000 }, new Employee() { Name = "Jack", Department = "R&D", Function = "Developer", Salary = 6000 }, new Employee() { Name = "Demy", Department = "Dev", Function = "Consultant", Salary = 2000 }}; var result5 = l.Pivot3(emp => emp.Department, emp2 => emp2.Function, lst => lst.Sum(emp => emp.Salary)); var result6 = l.Pivot3(emp => emp.Function, emp2 => emp2.Department, lst => lst.Count()); } 

*虽然不能说出表现。

Answer 3

您可以使用Linq的.ToLookup以您要查找的方式进行分组。

 var lookup = data.ToLookup(d => d.TypeCode, d => d.User); 

然后将它放入消费者可以理解的forms中。 例如：

 //Warning: untested code var enumerators = lookup.Select(g => g.GetEnumerator()).ToList(); int columns = enumerators.Count; while(columns > 0) { for(int i = 0; i < enumerators.Count; ++i) { var enumerator = enumerators[i]; if(enumator == null) continue; if(!enumerator.MoveNext()) { --columns; enumerators[i] = null; } } yield return enumerators.Select(e => (e != null) ? e.Current : null); } 

将它放在IEnumerable <>方法中，它将（可能）返回User的集合（列）的集合（行），其中null放在没有数据的列中。

Answer 4

我想这与Marc的答案类似，但我会发布它，因为我花了一些时间来处理它。 结果以" | "分隔，如您的示例所示。 当使用group by而不是构造新的匿名类型时，它还使用从LINQ查询返回的IGrouping类型。 这是经过测试的工作代码。

 var Items = new[] { new { TypeCode = 1, UserName = "Don Smith"}, new { TypeCode = 1, UserName = "Mike Jones"}, new { TypeCode = 1, UserName = "James Ray"}, new { TypeCode = 2, UserName = "Tom Rizzo"}, new { TypeCode = 2, UserName = "Alex Homes"}, new { TypeCode = 3, UserName = "Andy Bates"} }; var Columns = from i in Items group i.UserName by i.TypeCode; Dictionary> Rows = new Dictionary>(); int RowCount = Columns.Max(g => g.Count()); for (int i = 0; i <= RowCount; i++) // Row 0 is the header row. { Rows.Add(i, new List()); } int RowIndex; foreach (IGrouping c in Columns) { Rows[0].Add(c.Key.ToString()); RowIndex = 1; foreach (string user in c) { Rows[RowIndex].Add(user); RowIndex++; } for (int r = RowIndex; r <= Columns.Count(); r++) { Rows[r].Add(string.Empty); } } foreach (List row in Rows.Values) { Console.WriteLine(row.Aggregate((current, next) => current + " | " + next)); } Console.ReadLine(); 

我也用这个输入测试了它：

 var Items = new[] { new { TypeCode = 1, UserName = "Don Smith"}, new { TypeCode = 3, UserName = "Mike Jones"}, new { TypeCode = 3, UserName = "James Ray"}, new { TypeCode = 2, UserName = "Tom Rizzo"}, new { TypeCode = 2, UserName = "Alex Homes"}, new { TypeCode = 3, UserName = "Andy Bates"} }; 

其中产生了以下结果，表明第一列不需要包含最长的列表。 如果需要，您可以使用OrderBy获取TypeCode排序的列。

 1 | 3 | 2 Don Smith | Mike Jones | Tom Rizzo | James Ray | Alex Homes | Andy Bates | 

Answer 5

@ Sanjaya.Tio我对你的回答很感兴趣，并创建了这个改编，最大限度地减少了keySelector的执行。 （另）

 public static Dictionary> Pivot3( this IEnumerable source , Func key1Selector , Func key2Selector , Func, TValue> aggregate) { var lookup = source.ToLookup(x => new {Key1 = keySelector1(x), Key2 = keySelector2(x)}); List key1s = lookup.Select(g => g.Key.Key1).Distinct().ToList(); List key2s = lookup.Select(g => g.Key.Key2).Distinct().ToList(); var resultQuery = from key1 in key1s from key2 in key2s let lookupKey = new {Key1 = key1, Key2 = key2} let g = lookup[lookupKey] let resultValue = g.Any() ? aggregate(g) : default(TValue) select new {Key1 = key1, Key2 = key2, ResultValue = resultValue}; Dictionary> result = new Dictionary>(); foreach(var resultItem in resultQuery) { TKey1 key1 = resultItem.Key1; TKey2 key2 = resultItem.Key2; TValue resultValue = resultItem.ResultValue; if (!result.ContainsKey(key1)) { result[key1] = new Dictionary(); } var subDictionary = result[key1]; subDictionary[key2] = resultValue; } return result; }