在一個查詢多個列表去

Question

我有一系列的列表：

List<foo> spamSpamAndSpam; 
List<foo> spamSpamSpamSausageEggsAndSpam; 
List<foo> spamSpamSpamSausageEggsBaconAndSpam; 
List<foo> spamSpamSpamSpamSpamWithoutSpam; 
List<foo> spamSpamSpamSpamSpamSpamSpamSpamSpamLovelySpamWonderfulSpam; 

我也有一系列的值，我在foo屬性尋找：

List<string> Brian= new List<string>(); 
Brian.Add("Always"); 
Brian.Add("Look"); 
Brian.Add("On"); 
Brian.Add("The"); 
Brian.Add("Bright"); 
Brian.Add("Side"); 
Brian.Add("Of"); 
Brian.Add("Life"); 

我m會引用所有foo的參數，其中給定的屬性（比如bar）的值包含在後面的列表中。我做這樣的：

func<foo, bool> deadParrot = x => Brian.Contains(x.bar); 

IEnumerable<foo> okLumberjacks = spamSpamAndSpam.Where(deadParrot); 
okLumberjacks = okLumberjacks.Concat(
    spamSpamSpamSpamSausageEggsAndSpam.Where(deadParrot)); 

// And so on, concatenating the results of Where() from every list of <foo>. 

我需要每foo已經匹配濾波功能單一IEnumerable<foo>這樣我可以調用所有這些方法中一氣呵成，就像這樣：

foreach (foo incontinentRunner in okLumberjacks) 
{ 
    incontinentRunner.SillyWalk(); 
} 

所以我的問題是...是有辦法聚集在一個單一的集合中的每個foo，而無需求助於類似：

ni = ni.Concat(someList.Where(filter)); 

我意思是說，有沒有更好的方法來用Linq做這樣的事情？我在尋找類似：

okLumberjacks = spamSpamAndSpam. 
    And(spamSpamSpamSausageEggsAndSpam). 
    And(spamSpamSpamSausageEggsBaconAndSpam) /* etc */ .Where(deadParrot); 

甚至更​​好：

okLumberjacks = spanishInquisition.Where(deadParrot); 
// Where the type of spanishInquisition is List<List<foo>>. 

我不想因爲我需要他們，因爲他們是另一個操作以後修改的foo原有名單在代碼中。

Answer 1

創建一個列表的列表，然後只需壓平：

List<List<foo>> lists = new List<List<foo>>() 
{ 
    spamSpamAndSpam, 
    spamSpamSpamSausageEggsAndSpam, 
    //etc. 
}; 

IEnumerable<foo> items = lists.SelectMany(item => item); 
//do stuff with items. 

Answer 2

我能想到的最好的將是這樣的：

var everything = spam1.Concat(spam2).Concat(spam3); 
var itemsIWant = everything.Where(x => Brian.Contains(x)); 

Answer 3

確實聯盟（）解決問題了嗎？

 List<foo> spamSpamAndSpam; 
     List<foo> spamSpamSpamSausageEggsAndSpam; 
     List<foo> spamSpamSpamSausageEggsBaconAndSpam; 
     List<foo> spamSpamSpamSpamSpamWithoutSpam; 
     List<foo> spamSpamSpamSpamSpamSpamSpamSpamSpamLovelySpamWonderfulSpam; 

     var x = spamSpamAndSpam 
      .Union(spamSpamSpamSausageEggsAndSpam) 
      .Union(spamSpamSpamSausageEggsBaconAndSpam) 
      .Union(spamSpamSpamSausageEggsBaconAndSpam) 
      .Union(spamSpamSpamSpamSpamWithoutSpam) 
      .Union(spamSpamSpamSpamSpamSpamSpamSpamSpamLovelySpamWonderfulSpam) 
      .Where(x => .....); 

注：，因爲它被正確地指出，Union排除從返回集中的重複。這與Concat方法的行爲不同，後者返回輸入序列中的所有元素，包括重複項。由於不需要重複排除，因此Concat可能更好