लैम्बडा

Question

का उपयोग कर एकाधिक कॉलम के साथ समूह lambda का उपयोग करके मैं एकाधिक कॉलम के साथ कैसे समूह कर सकता हूं?

मैंने उदाहरणों के लिए linq का उपयोग करके इसे कैसे किया जाए, लेकिन मैं लैम्ब्डा रूप की तलाश में हूं।

Answer 1

var query = source.GroupBy(x => new { x.Column1, x.Column2 }); 

Answer 2

यदि आपकी तालिका के ऊपर इस

rowId  col1 col2 col3 col4 
1   a  e  12  2 
2   b  f  42  5 
3   a  e  32  2 
4   b  f  44  5 


var grouped = myTable.AsEnumerable().GroupBy(r=> new {pp1 = r.Field<int>("col1"), pp2 = r.Field<int>("col2")}); 

Answer 3

इसके अलावा aduchis का जवाब की तरह है - यदि आप तो कुंजी द्वारा उन समूह के आधार पर फ़िल्टर करने की जरूरत है, आप कई कुंजी रैप करने के लिए एक वर्ग को परिभाषित कर सकते हैं।

return customers.GroupBy(a => new CustomerGroupingKey(a.Country, a.Gender)) 
       .Where(a => a.Key.Country == "Ireland" && a.Key.Gender == "M") 
       .SelectMany(a => a) 
       .ToList(); 

कहाँ CustomerGroupingKey समूह प्रयास लगता है:

private class CustomerGroupingKey 
    { 
     public CustomerGroupingKey(string country, string gender) 
     { 
      Country = country; 
      Gender = gender; 
     } 

     public string Country { get; } 

     public string Gender { get; } 
    } 

Answer 4

 class Element 
     { 
      public string Company;   
      public string TypeOfInvestment; 
      public decimal Worth; 
     } 

    class Program 
    { 
     static void Main(string[] args) 
     { 
     List<Element> elements = new List<Element>() 
      { 
       new Element { Company = "JPMORGAN CHASE",TypeOfInvestment = "Stocks", Worth = 96983 }, 
       new Element { Company = "AMER TOWER CORP",TypeOfInvestment = "Securities", Worth = 17141 }, 
       new Element { Company = "ORACLE CORP",TypeOfInvestment = "Assets", Worth = 59372 }, 
       new Element { Company = "PEPSICO INC",TypeOfInvestment = "Assets", Worth = 26516 }, 
       new Element { Company = "PROCTER & GAMBL",TypeOfInvestment = "Stocks", Worth = 387050 }, 
       new Element { Company = "QUASLCOMM INC",TypeOfInvestment = "Bonds", Worth = 196811 }, 
       new Element { Company = "UTD TECHS CORP",TypeOfInvestment = "Bonds", Worth = 257429 }, 
       new Element { Company = "WELLS FARGO-NEW",TypeOfInvestment = "Bank Account", Worth = 106600 }, 
       new Element { Company = "FEDEX CORP",TypeOfInvestment = "Stocks", Worth = 103955 }, 
       new Element { Company = "CVS CAREMARK CP",TypeOfInvestment = "Securities", Worth = 171048 }, 
      }; 

      //Group by on multiple column in LINQ (Query Method) 
      var query = from e in elements 
         group e by new{e.TypeOfInvestment,e.Company} into eg 
         select new {eg.Key.TypeOfInvestment, eg.Key.Company, Points = eg.Sum(rl => rl.Worth)}; 



      foreach (var item in query) 
      { 
       Console.WriteLine(item.TypeOfInvestment.PadRight(20) + " " + item.Points.ToString()); 
      } 


      //Group by on multiple column in LINQ (Lambda Method) 
      var CompanyDetails =elements.GroupBy(s => new { s.Company, s.TypeOfInvestment}) 
           .Select(g => 
              new 
              { 
               company = g.Key.Company, 
               TypeOfInvestment = g.Key.TypeOfInvestment,    
               Balance = g.Sum(x => Math.Round(Convert.ToDecimal(x.Worth), 2)), 
              } 
            ); 
      foreach (var item in CompanyDetails) 
      { 
       Console.WriteLine(item.TypeOfInvestment.PadRight(20) + " " + item.Balance.ToString()); 
      } 
      Console.ReadLine(); 

     } 
    }