群和总结选择许多C＃？

我有一个传入的数组，每行的计数和一个字符串表示一个或多个按键的下划线分隔。群和总结选择许多C＃？

每个我想组和求和总其中如果键出现在一行中，共有5，通过下划线分割的每个项目具有它们的总增加5

我被键只是不知道如何做到这一点的LINQ表示...

class Owl 
    { 
     public int SpeciesCount { get; set; } 
     public string BandIdentifier { get; set; } 
    } 

public class GoOwl 
{ 
    public GoOwl(Owl[] owls) 
    { 
     //just making a list of test data to illustrate what would be coming in on the array 
     var owlList = new List<Owl>(); 
     owlList.Add(new Owl { SpeciesCount = 2, BandIdentifier = "OWL1" }); 
     owlList.Add(new Owl { SpeciesCount = 1, BandIdentifier = "OWL1_OWL2_OWL3" }); 
     owlList.Add(new Owl { SpeciesCount = 2, BandIdentifier = "OWL3" }); 
     owlList.Add(new Owl { SpeciesCount = 5, BandIdentifier = "OWL2_OWL3" }); 

     //i'd ideally like to have something like a row for each band identifier split on underscore plus a total species count.. 
     //where you'd sum the species count for each underscored item and group 


    } 
}

以下将所需的输出为单猫头鹰对象

["OWL1", 3] 
["OWL2", 6] 
["OWL3", 8]

我仍然不是很让小号electMany ..

干杯

来源

2013-05-07 TheLearningDev

用流利的sytnax：

//For each 'owlItem' in the owlList, select an anonymous objects for each key in the BandIdentifier string, keeping track of the associated SpeciesCount 
//Since each call to Split('_').Select(...) produces an IEnumerable of those anonymous objects, use SelectMany to flatten the IEnumerable to IEnumerables 
owlList.SelectMany(owlItem => owlItem.BandIdentifier.Split('_') 
       .Select(key => new { OwlKey = key, owlItem.SpeciesCount })) 
      //Group together those anonymous objects if they share the same key 
      .GroupBy(info => info.OwlKey) 
      //For each of the groups, sum together all the associated SpeciesCounts 
      .Select(group => new { group.Key, SpeciesCount = group.Sum(info => info.SpeciesCount) })'

来源

2013-05-07 14:23:10

谢谢Ben！你介意在这种情况下解释selectmany的工作原理吗？我知道它会展平嵌套的集合，所以在这个例子中，它是在执行以下的操作：[OWL1 2] [OWL1 1] [OWL2 1] [OWL3 1] [OWL3 2] [OWL2 5] [OWL3 5]那么按组上的密钥然后你可以总结？ – TheLearningDev 2013-05-07 15:25:19

每次调用.Split（'_'）。选择（...）将生成一个IEnumerable。由于我们正在为owlList变量的每个元素调用该方法链，所以我们有一个IEnumerable的IEnumerables，可以使用SelectMany进行展平。换句话说，由于列表中的每个元素都会生成一个OwlKey/SpeciesCount组合列表，所以在开始分组和求和之前，我们需要将列表生成的列表展平。 – 2013-05-07 15:33:15

感谢本和谢谢你的解释我很感激你花时间！ :) – TheLearningDev 2013-05-07 22:21:21

好像你想要这个：

var results = 
    owlList.SelectMany(owl => owl.BandIdentifier.Split('_'), 
         (owl, band) => new { owl, band }) 
      .GroupBy(x => x.band) 
      .Select(group => new Owl 
        { 
         BandIdentifier = group.Key 
         SpeciesCount = group.Sum(g => g.SpeciesCount) 
        });

或者在查询语法：

var results = 
    from owl in owlList 
    from band in owl.BandIdentifier.Split('_') 
    group owl by band into group 
    select new Owl { 
     BandIdentifier = group.Key 
     SpeciesCount = group.Sum(g => g.SpeciesCount) 
    };

来源

2013-05-07 14:18:31

var owlResults = owlList 
      //Use SelectMany to split and select all species 
      //and have a select to get the count along with the species 
      .SelectMany(O => O.BandIdentifier.Split('_') 
       .Select(owl => new { Species = owl, Count = O.SpeciesCount })) 
      //Here you can group and get the sum 
      .GroupBy(O => O.Species) 
      .Select(owl => new { Species = owl.Key, Count = owl.Sum(o => o.Count) });

来源

2013-05-07 15:01:47 arunlalam

群和总结选择许多C＃？

回答

相关问题