c# - Perform Calculations Within List Using Linq and Lambda Expressions -

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i have following object:

public class foo {     public int32 id      public int32 sampleid      public int32 companyid      public decimal data  }  public class bar {     public int32 companyid      public decimal data   }

i have list of these objects. want perform calculation group ids "companyid" first. each company id, add 3 different sampleids data , returning new object each company.

//i want data sampleid = 2, 4 , 6 added  //from foo object , put data of new bar object. list.groupby(l => l.companyid).select( x => new bar { companyid = x.key, ????? } );

i stuck how perform calculation after grouping. appreciated.

you pretty close me.

this should work:

    var list = new list<foo>                    {                        new foo { companyid = 1, data = 15, id = 1, sampleid = 2 },                        new foo { companyid = 1, data = 10, id = 2, sampleid = 4 },                        new foo { companyid = 1, data = 25, id = 2, sampleid = 6 }                    };      var output = list.groupby(         l => l.companyid,         (key, data) => new bar { companyid = key, data = data.sum(d => d.data) });

or if want filter out 2,4,6 sample id (can't understand why honest) work:

[test] public void testing() {     var list = new list<foo>                    {                        new foo { companyid = 1, data = 15, id = 1, sampleid = 2 },                        new foo { companyid = 1, data = 10, id = 2, sampleid = 4 },                        new foo { companyid = 1, data = 25, id = 3, sampleid = 8 },                        new foo { companyid = 1, data = 25, id = 4, sampleid = 12 },                        new foo { companyid = 1, data = 25, id = 5, sampleid = 14 }                    };      var filterlist = new list<int> { 2, 4, 6 };      var output = list.where(l => filterlist.contains(l.sampleid))         .groupby(l => l.companyid, (key, data) => new bar { companyid = key, data = data.sum(d => d.data) });      assert.true(output != null);     assert.true(output.firstordefault() != null);     assert.true(output.firstordefault().data == 25); }

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